update lodepng to the latest version

5 files changed, 4042 insertions, 2512 deletions

diff --git a/src/zopflipng/lodepng/lodepng.cpp b/src/zopflipng/lodepng/lodepng.cpp
index 59e3af9..02bf99b 100644
--- a/src/zopflipng/lodepng/lodepng.cpp
+++ b/src/zopflipng/lodepng/lodepng.cpp
@@ -1,7 +1,7 @@
 /*
-LodePNG version 20160409
+LodePNG version 20190914
 
-Copyright (c) 2005-2016 Lode Vandevenne
+Copyright (c) 2005-2019 Lode Vandevenne
 
 This software is provided 'as-is', without any express or implied
 warranty. In no event will the authors be held liable for any damages
@@ -30,16 +30,21 @@ Rename this file to lodepng.cpp to use it for C++, or to lodepng.c to use it for
 
 #include "lodepng.h"
 
-#include <limits.h>
-#include <stdio.h>
-#include <stdlib.h>
+#ifdef LODEPNG_COMPILE_DISK
+#include <limits.h> /* LONG_MAX */
+#include <stdio.h> /* file handling */
+#endif /* LODEPNG_COMPILE_DISK */
+
+#ifdef LODEPNG_COMPILE_ALLOCATORS
+#include <stdlib.h> /* allocations */
+#endif /* LODEPNG_COMPILE_ALLOCATORS */
 
 #if defined(_MSC_VER) && (_MSC_VER >= 1310) /*Visual Studio: A few warning types are not desired here.*/
 #pragma warning( disable : 4244 ) /*implicit conversions: not warned by gcc -Wall -Wextra and requires too much casts*/
 #pragma warning( disable : 4996 ) /*VS does not like fopen, but fopen_s is not standard C so unusable here*/
 #endif /*_MSC_VER */
 
-const char* LODEPNG_VERSION_STRING = "20160409";
+const char* LODEPNG_VERSION_STRING = "20190914";
 
 /*
 This source file is built up in the following large parts. The code sections
@@ -50,6 +55,12 @@ with the "LODEPNG_COMPILE_" #defines divide this up further in an intermixed way
 -The C++ wrapper around all of the above
 */
 
+/* ////////////////////////////////////////////////////////////////////////// */
+/* ////////////////////////////////////////////////////////////////////////// */
+/* // Tools for C, and common code for PNG and Zlib.                       // */
+/* ////////////////////////////////////////////////////////////////////////// */
+/* ////////////////////////////////////////////////////////////////////////// */
+
 /*The malloc, realloc and free functions defined here with "lodepng_" in front
 of the name, so that you can easily change them to others related to your
 platform if needed. Everything else in the code calls these. Pass
@@ -60,31 +71,95 @@ lodepng source code. Don't forget to remove "static" if you copypaste them
 from here.*/
 
 #ifdef LODEPNG_COMPILE_ALLOCATORS
-static void* lodepng_malloc(size_t size)
-{
+static void* lodepng_malloc(size_t size) {
+#ifdef LODEPNG_MAX_ALLOC
+  if(size > LODEPNG_MAX_ALLOC) return 0;
+#endif
   return malloc(size);
 }
 
-static void* lodepng_realloc(void* ptr, size_t new_size)
-{
+static void* lodepng_realloc(void* ptr, size_t new_size) {
+#ifdef LODEPNG_MAX_ALLOC
+  if(new_size > LODEPNG_MAX_ALLOC) return 0;
+#endif
   return realloc(ptr, new_size);
 }
 
-static void lodepng_free(void* ptr)
-{
+static void lodepng_free(void* ptr) {
   free(ptr);
 }
 #else /*LODEPNG_COMPILE_ALLOCATORS*/
+/* TODO: support giving additional void* payload to the custom allocators */
 void* lodepng_malloc(size_t size);
 void* lodepng_realloc(void* ptr, size_t new_size);
 void lodepng_free(void* ptr);
 #endif /*LODEPNG_COMPILE_ALLOCATORS*/
 
-/* ////////////////////////////////////////////////////////////////////////// */
-/* ////////////////////////////////////////////////////////////////////////// */
-/* // Tools for C, and common code for PNG and Zlib.                       // */
-/* ////////////////////////////////////////////////////////////////////////// */
-/* ////////////////////////////////////////////////////////////////////////// */
+/* convince the compiler to inline a function, for use when this measurably improves performance */
+/* inline is not available in C90, but use it when supported by the compiler */
+#if (defined(__STDC_VERSION__) && (__STDC_VERSION__ >= 199901L)) || (defined(__cplusplus) && (__cplusplus >= 199711L))
+#define LODEPNG_INLINE inline
+#else
+#define LODEPNG_INLINE /* not available */
+#endif
+
+/* restrict is not available in C90, but use it when supported by the compiler */
+#if (defined(__GNUC__) && defined(__GNUC_MINOR__) && (__GNUC__ >= 3) && (__GNUC_MINOR__ >= 1)) ||\
+    (defined(_MSC_VER) && (_MSC_VER >= 1400)) || (defined(__WATCOMC__) && (__WATCOMC__ >= 1250))
+#define LODEPNG_RESTRICT __restrict
+#else
+#define LODEPNG_RESTRICT /* not available */
+#endif
+
+/* Replacements for C library functions memcpy and strlen, to support those platforms
+where a full C library is not available. The compiler can recognize them and compile
+to something as fast. */
+
+static void lodepng_memcpy(void* LODEPNG_RESTRICT dst,
+                           const void* LODEPNG_RESTRICT src, size_t size) {
+  size_t i;
+  for(i = 0; i < size; i++) ((char*)dst)[i] = ((const char*)src)[i];
+}
+
+/* does not check memory out of bounds, do not use on untrusted data */
+static size_t lodepng_strlen(const char* a) {
+  const char* orig = a;
+  /* avoid warning about unused function in case of disabled COMPILE... macros */
+  (void)lodepng_strlen;
+  while(*a) a++;
+  return (size_t)(a - orig);
+}
+
+#define LODEPNG_MAX(a, b) (((a) > (b)) ? (a) : (b))
+#define LODEPNG_MIN(a, b) (((a) < (b)) ? (a) : (b))
+#define LODEPNG_ABS(x) ((x) < 0 ? -(x) : (x))
+
+
+#ifdef LODEPNG_COMPILE_DECODER
+/* Safely check if multiplying two integers will overflow (no undefined
+behavior, compiler removing the code, etc...) and output result. */
+static int lodepng_mulofl(size_t a, size_t b, size_t* result) {
+  *result = a * b; /* Unsigned multiplication is well defined and safe in C90 */
+  return (a != 0 && *result / a != b);
+}
+
+/* Safely check if adding two integers will overflow (no undefined
+behavior, compiler removing the code, etc...) and output result. */
+static int lodepng_addofl(size_t a, size_t b, size_t* result) {
+  *result = a + b; /* Unsigned addition is well defined and safe in C90 */
+  return *result < a;
+}
+
+#ifdef LODEPNG_COMPILE_ZLIB
+/* Safely check if a + b > c, even if overflow could happen. */
+static int lodepng_gtofl(size_t a, size_t b, size_t c) {
+  size_t d;
+  if(lodepng_addofl(a, b, &d)) return 1;
+  return d > c;
+}
+#endif /*LODEPNG_COMPILE_ZLIB*/
+#endif /*LODEPNG_COMPILE_DECODER*/
+
 
 /*
 Often in case of an error a value is assigned to a variable and then it breaks
@@ -93,8 +168,7 @@ It makes the error handling code shorter and more readable.
 
 Example: if(!uivector_resizev(&frequencies_ll, 286, 0)) ERROR_BREAK(83);
 */
-#define CERROR_BREAK(errorvar, code)\
-{\
+#define CERROR_BREAK(errorvar, code){\
   errorvar = code;\
   break;\
 }
@@ -103,22 +177,19 @@ Example: if(!uivector_resizev(&frequencies_ll, 286, 0)) ERROR_BREAK(83);
 #define ERROR_BREAK(code) CERROR_BREAK(error, code)
 
 /*Set error var to the error code, and return it.*/
-#define CERROR_RETURN_ERROR(errorvar, code)\
-{\
+#define CERROR_RETURN_ERROR(errorvar, code){\
   errorvar = code;\
   return code;\
 }
 
 /*Try the code, if it returns error, also return the error.*/
-#define CERROR_TRY_RETURN(call)\
-{\
+#define CERROR_TRY_RETURN(call){\
   unsigned error = call;\
   if(error) return error;\
 }
 
 /*Set error var to the error code, and return from the void function.*/
-#define CERROR_RETURN(errorvar, code)\
-{\
+#define CERROR_RETURN(errorvar, code){\
   errorvar = code;\
   return;\
 }
@@ -133,30 +204,26 @@ About uivector, ucvector and string:
 */
 
 #ifdef LODEPNG_COMPILE_ZLIB
+#ifdef LODEPNG_COMPILE_ENCODER
 /*dynamic vector of unsigned ints*/
-typedef struct uivector
-{
+typedef struct uivector {
   unsigned* data;
   size_t size; /*size in number of unsigned longs*/
   size_t allocsize; /*allocated size in bytes*/
 } uivector;
 
-static void uivector_cleanup(void* p)
-{
+static void uivector_cleanup(void* p) {
   ((uivector*)p)->size = ((uivector*)p)->allocsize = 0;
   lodepng_free(((uivector*)p)->data);
   ((uivector*)p)->data = NULL;
 }
 
 /*returns 1 if success, 0 if failure ==> nothing done*/
-static unsigned uivector_reserve(uivector* p, size_t allocsize)
-{
-  if(allocsize > p->allocsize)
-  {
-    size_t newsize = (allocsize > p->allocsize * 2) ? allocsize : (allocsize * 3 / 2);
+static unsigned uivector_reserve(uivector* p, size_t allocsize) {
+  if(allocsize > p->allocsize) {
+    size_t newsize = (allocsize > p->allocsize * 2u) ? allocsize : ((allocsize * 3u) >> 1u);
     void* data = lodepng_realloc(p->data, newsize);
-    if(data)
-    {
+    if(data) {
       p->allocsize = newsize;
       p->data = (unsigned*)data;
     }
@@ -166,32 +233,27 @@ static unsigned uivector_reserve(uivector* p, size_t allocsize)
 }
 
 /*returns 1 if success, 0 if failure ==> nothing done*/
-static unsigned uivector_resize(uivector* p, size_t size)
-{
+static unsigned uivector_resize(uivector* p, size_t size) {
   if(!uivector_reserve(p, size * sizeof(unsigned))) return 0;
   p->size = size;
   return 1; /*success*/
 }
 
 /*resize and give all new elements the value*/
-static unsigned uivector_resizev(uivector* p, size_t size, unsigned value)
-{
+static unsigned uivector_resizev(uivector* p, size_t size, unsigned value) {
   size_t oldsize = p->size, i;
   if(!uivector_resize(p, size)) return 0;
   for(i = oldsize; i < size; ++i) p->data[i] = value;
   return 1;
 }
 
-static void uivector_init(uivector* p)
-{
+static void uivector_init(uivector* p) {
   p->data = NULL;
   p->size = p->allocsize = 0;
 }
 
-#ifdef LODEPNG_COMPILE_ENCODER
 /*returns 1 if success, 0 if failure ==> nothing done*/
-static unsigned uivector_push_back(uivector* p, unsigned c)
-{
+static unsigned uivector_push_back(uivector* p, unsigned c) {
   if(!uivector_resize(p, p->size + 1)) return 0;
   p->data[p->size - 1] = c;
   return 1;
@@ -202,22 +264,18 @@ static unsigned uivector_push_back(uivector* p, unsigned c)
 /* /////////////////////////////////////////////////////////////////////////// */
 
 /*dynamic vector of unsigned chars*/
-typedef struct ucvector
-{
+typedef struct ucvector {
   unsigned char* data;
   size_t size; /*used size*/
   size_t allocsize; /*allocated size*/
 } ucvector;
 
 /*returns 1 if success, 0 if failure ==> nothing done*/
-static unsigned ucvector_reserve(ucvector* p, size_t allocsize)
-{
-  if(allocsize > p->allocsize)
-  {
-    size_t newsize = (allocsize > p->allocsize * 2) ? allocsize : (allocsize * 3 / 2);
+static unsigned ucvector_reserve(ucvector* p, size_t allocsize) {
+  if(allocsize > p->allocsize) {
+    size_t newsize = (allocsize > p->allocsize * 2u) ? allocsize : ((allocsize * 3u) >> 1u);
     void* data = lodepng_realloc(p->data, newsize);
-    if(data)
-    {
+    if(data) {
       p->allocsize = newsize;
       p->data = (unsigned char*)data;
     }
@@ -227,8 +285,7 @@ static unsigned ucvector_reserve(ucvector* p, size_t allocsize)
 }
 
 /*returns 1 if success, 0 if failure ==> nothing done*/
-static unsigned ucvector_resize(ucvector* p, size_t size)
-{
+static unsigned ucvector_resize(ucvector* p, size_t size) {
   if(!ucvector_reserve(p, size * sizeof(unsigned char))) return 0;
   p->size = size;
   return 1; /*success*/
@@ -236,25 +293,22 @@ static unsigned ucvector_resize(ucvector* p, size_t size)
 
 #ifdef LODEPNG_COMPILE_PNG
 
-static void ucvector_cleanup(void* p)
-{
+static void ucvector_cleanup(void* p) {
   ((ucvector*)p)->size = ((ucvector*)p)->allocsize = 0;
   lodepng_free(((ucvector*)p)->data);
   ((ucvector*)p)->data = NULL;
 }
 
-static void ucvector_init(ucvector* p)
-{
+static void ucvector_init(ucvector* p) {
   p->data = NULL;
   p->size = p->allocsize = 0;
 }
 #endif /*LODEPNG_COMPILE_PNG*/
 
 #ifdef LODEPNG_COMPILE_ZLIB
-/*you can both convert from vector to buffer&size and vica versa. If you use
+/*you can both convert from vector to buffer&size and vice versa. If you use
 init_buffer to take over a buffer and size, it is not needed to use cleanup*/
-static void ucvector_init_buffer(ucvector* p, unsigned char* buffer, size_t size)
-{
+static void ucvector_init_buffer(ucvector* p, unsigned char* buffer, size_t size) {
   p->data = buffer;
   p->allocsize = p->size = size;
 }
@@ -262,8 +316,7 @@ static void ucvector_init_buffer(ucvector* p, unsigned char* buffer, size_t size
 
 #if (defined(LODEPNG_COMPILE_PNG) && defined(LODEPNG_COMPILE_ANCILLARY_CHUNKS)) || defined(LODEPNG_COMPILE_ENCODER)
 /*returns 1 if success, 0 if failure ==> nothing done*/
-static unsigned ucvector_push_back(ucvector* p, unsigned char c)
-{
+static unsigned ucvector_push_back(ucvector* p, unsigned char c) {
   if(!ucvector_resize(p, p->size + 1)) return 0;
   p->data[p->size - 1] = c;
   return 1;
@@ -275,57 +328,41 @@ static unsigned ucvector_push_back(ucvector* p, unsigned char c)
 
 #ifdef LODEPNG_COMPILE_PNG
 #ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS
-/*returns 1 if success, 0 if failure ==> nothing done*/
-static unsigned string_resize(char** out, size_t size)
-{
-  char* data = (char*)lodepng_realloc(*out, size + 1);
-  if(data)
-  {
-    data[size] = 0; /*null termination char*/
-    *out = data;
-  }
-  return data != 0;
-}
-
-/*init a {char*, size_t} pair for use as string*/
-static void string_init(char** out)
-{
-  *out = NULL;
-  string_resize(out, 0);
-}
 
-/*free the above pair again*/
-static void string_cleanup(char** out)
-{
+/*free string pointer and set it to NULL*/
+static void string_cleanup(char** out) {
   lodepng_free(*out);
   *out = NULL;
 }
 
-static void string_set(char** out, const char* in)
-{
-  size_t insize = strlen(in), i;
-  if(string_resize(out, insize))
-  {
-    for(i = 0; i != insize; ++i)
-    {
-      (*out)[i] = in[i];
+/* dynamically allocates a new string with a copy of the null terminated input text */
+static char* alloc_string(const char* in) {
+  size_t insize = lodepng_strlen(in);
+  char* out = (char*)lodepng_malloc(insize + 1);
+  if(out) {
+    size_t i;
+    for(i = 0; i != insize; ++i) {
+      out[i] = in[i];
     }
+    out[i] = 0;
   }
+  return out;
 }
 #endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/
 #endif /*LODEPNG_COMPILE_PNG*/
 
 /* ////////////////////////////////////////////////////////////////////////// */
 
-unsigned lodepng_read32bitInt(const unsigned char* buffer)
-{
-  return (unsigned)((buffer[0] << 24) | (buffer[1] << 16) | (buffer[2] << 8) | buffer[3]);
+#if defined(LODEPNG_COMPILE_DECODER) || defined(LODEPNG_COMPILE_PNG)
+static unsigned lodepng_read32bitInt(const unsigned char* buffer) {
+  return (((unsigned)buffer[0] << 24u) | ((unsigned)buffer[1] << 16u) |
+         ((unsigned)buffer[2] << 8u) | (unsigned)buffer[3]);
 }
+#endif /*defined(LODEPNG_COMPILE_DECODER) || defined(LODEPNG_COMPILE_PNG)*/
 
 #if defined(LODEPNG_COMPILE_PNG) || defined(LODEPNG_COMPILE_ENCODER)
 /*buffer must have at least 4 allocated bytes available*/
-static void lodepng_set32bitInt(unsigned char* buffer, unsigned value)
-{
+static void lodepng_set32bitInt(unsigned char* buffer, unsigned value) {
   buffer[0] = (unsigned char)((value >> 24) & 0xff);
   buffer[1] = (unsigned char)((value >> 16) & 0xff);
   buffer[2] = (unsigned char)((value >>  8) & 0xff);
@@ -333,14 +370,6 @@ static void lodepng_set32bitInt(unsigned char* buffer, unsigned value)
 }
 #endif /*defined(LODEPNG_COMPILE_PNG) || defined(LODEPNG_COMPILE_ENCODER)*/
 
-#ifdef LODEPNG_COMPILE_ENCODER
-static void lodepng_add32bitInt(ucvector* buffer, unsigned value)
-{
-  ucvector_resize(buffer, buffer->size + 4); /*todo: give error if resize failed*/
-  lodepng_set32bitInt(&buffer->data[buffer->size - 4], value);
-}
-#endif /*LODEPNG_COMPILE_ENCODER*/
-
 /* ////////////////////////////////////////////////////////////////////////// */
 /* / File IO                                                                / */
 /* ////////////////////////////////////////////////////////////////////////// */
@@ -348,15 +377,13 @@ static void lodepng_add32bitInt(ucvector* buffer, unsigned value)
 #ifdef LODEPNG_COMPILE_DISK
 
 /* returns negative value on error. This should be pure C compatible, so no fstat. */
-static long lodepng_filesize(const char* filename)
-{
+static long lodepng_filesize(const char* filename) {
   FILE* file;
   long size;
   file = fopen(filename, "rb");
   if(!file) return -1;
 
-  if(fseek(file, 0, SEEK_END) != 0)
-  {
+  if(fseek(file, 0, SEEK_END) != 0) {
     fclose(file);
     return -1;
   }
@@ -370,8 +397,7 @@ static long lodepng_filesize(const char* filename)
 }
 
 /* load file into buffer that already has the correct allocated size. Returns error code.*/
-static unsigned lodepng_buffer_file(unsigned char* out, size_t size, const char* filename)
-{
+static unsigned lodepng_buffer_file(unsigned char* out, size_t size, const char* filename) {
   FILE* file;
   size_t readsize;
   file = fopen(filename, "rb");
@@ -384,8 +410,7 @@ static unsigned lodepng_buffer_file(unsigned char* out, size_t size, const char*
   return 0;
 }
 
-unsigned lodepng_load_file(unsigned char** out, size_t* outsize, const char* filename)
-{
+unsigned lodepng_load_file(unsigned char** out, size_t* outsize, const char* filename) {
   long size = lodepng_filesize(filename);
   if (size < 0) return 78;
   *outsize = (size_t)size;
@@ -397,12 +422,11 @@ unsigned lodepng_load_file(unsigned char** out, size_t* outsize, const char* fil
 }
 
 /*write given buffer to the file, overwriting the file, it doesn't append to it.*/
-unsigned lodepng_save_file(const unsigned char* buffer, size_t buffersize, const char* filename)
-{
+unsigned lodepng_save_file(const unsigned char* buffer, size_t buffersize, const char* filename) {
   FILE* file;
   file = fopen(filename, "wb" );
   if(!file) return 79;
-  fwrite((char*)buffer , 1 , buffersize, file);
+  fwrite(buffer, 1, buffersize, file);
   fclose(file);
   return 0;
 }
@@ -417,52 +441,187 @@ unsigned lodepng_save_file(const unsigned char* buffer, size_t buffersize, const
 
 #ifdef LODEPNG_COMPILE_ZLIB
 #ifdef LODEPNG_COMPILE_ENCODER
+
+typedef struct {
+  ucvector* data;
+  size_t bp;
+} LodePNGBitWriter;
+
+void LodePNGBitWriter_init(LodePNGBitWriter* writer, ucvector* data) {
+  writer->data = data;
+  writer->bp = 0;
+}
+
 /*TODO: this ignores potential out of memory errors*/
-#define addBitToStream(/*size_t**/ bitpointer, /*ucvector**/ bitstream, /*unsigned char*/ bit)\
-{\
-  /*add a new byte at the end*/\
-  if(((*bitpointer) & 7) == 0) ucvector_push_back(bitstream, (unsigned char)0);\
-  /*earlier bit of huffman code is in a lesser significant bit of an earlier byte*/\
-  (bitstream->data[bitstream->size - 1]) |= (bit << ((*bitpointer) & 0x7));\
-  ++(*bitpointer);\
+#define WRITEBIT(/*size_t**/ writer, /*unsigned char*/ bit){\
+  /* append new byte */\
+  if(((writer->bp) & 7u) == 0) ucvector_push_back(writer->data, (unsigned char)0);\
+  (writer->data->data[writer->data->size - 1]) |= (bit << ((writer->bp) & 7u));\
+  ++writer->bp;\
 }
 
-static void addBitsToStream(size_t* bitpointer, ucvector* bitstream, unsigned value, size_t nbits)
-{
-  size_t i;
-  for(i = 0; i != nbits; ++i) addBitToStream(bitpointer, bitstream, (unsigned char)((value >> i) & 1));
+/* LSB of value is written first, and LSB of bytes is used first */
+static void writeBits(LodePNGBitWriter* writer, unsigned value, size_t nbits) {
+  if(nbits == 1) { /* compiler should statically compile this case if nbits == 1 */
+    WRITEBIT(writer, value);
+  } else {
+    /* TODO: increase output size nly once here rather than in each WRITEBIT */
+    size_t i;
+    for(i = 0; i != nbits; ++i) {
+      WRITEBIT(writer, (unsigned char)((value >> i) & 1));
+    }
+  }
 }
 
-static void addBitsToStreamReversed(size_t* bitpointer, ucvector* bitstream, unsigned value, size_t nbits)
-{
+/* This one is to use for adding huffman symbol, the value bits are written MSB first */
+static void writeBitsReversed(LodePNGBitWriter* writer, unsigned value, size_t nbits) {
   size_t i;
-  for(i = 0; i != nbits; ++i) addBitToStream(bitpointer, bitstream, (unsigned char)((value >> (nbits - 1 - i)) & 1));
+  for(i = 0; i != nbits; ++i) {
+    /* TODO: increase output size only once here rather than in each WRITEBIT */
+    WRITEBIT(writer, (unsigned char)((value >> (nbits - 1u - i)) & 1u));
+  }
 }
 #endif /*LODEPNG_COMPILE_ENCODER*/
 
 #ifdef LODEPNG_COMPILE_DECODER
 
-#define READBIT(bitpointer, bitstream) ((bitstream[bitpointer >> 3] >> (bitpointer & 0x7)) & (unsigned char)1)
-
-static unsigned char readBitFromStream(size_t* bitpointer, const unsigned char* bitstream)
-{
-  unsigned char result = (unsigned char)(READBIT(*bitpointer, bitstream));
-  ++(*bitpointer);
-  return result;
+typedef struct {
+  const unsigned char* data;
+  size_t size; /*size of data in bytes*/
+  size_t bitsize; /*size of data in bits, end of valid bp values, should be 8*size*/
+  size_t bp;
+  unsigned buffer; /*buffer for reading bits. NOTE: 'unsigned' must support at least 32 bits*/
+} LodePNGBitReader;
+
+/* data size argument is in bytes. Returns error if size too large causing overflow */
+static unsigned LodePNGBitReader_init(LodePNGBitReader* reader, const unsigned char* data, size_t size) {
+  size_t temp;
+  reader->data = data;
+  reader->size = size;
+  /* size in bits, return error if overflow (if size_t is 32 bit this supports up to 500MB)  */
+  if(lodepng_mulofl(size, 8u, &reader->bitsize)) return 105;
+  /*ensure incremented bp can be compared to bitsize without overflow even when it would be incremented 32 too much and
+  trying to ensure 32 more bits*/
+  if(lodepng_addofl(reader->bitsize, 64u, &temp)) return 105;
+  reader->bp = 0;
+  reader->buffer = 0;
+  return 0; /*ok*/
 }
 
-static unsigned readBitsFromStream(size_t* bitpointer, const unsigned char* bitstream, size_t nbits)
-{
-  unsigned result = 0, i;
-  for(i = 0; i != nbits; ++i)
-  {
-    result += ((unsigned)READBIT(*bitpointer, bitstream)) << i;
-    ++(*bitpointer);
+/*
+ensureBits functions:
+Ensures the reader can at least read nbits bits in one or more readBits calls,
+safely even if not enough bits are available.
+Returns 1 if there are enough bits available, 0 if not.
+*/
+
+/*See ensureBits documentation above. This one ensures exactly 1 bit */
+/*static unsigned ensureBits1(LodePNGBitReader* reader) {
+  if(reader->bp >= reader->bitsize) return 0;
+  reader->buffer = (unsigned)reader->data[reader->bp >> 3u] >> (reader->bp & 7u);
+  return 1;
+}*/
+
+/*See ensureBits documentation above. This one ensures up to 9 bits */
+static unsigned ensureBits9(LodePNGBitReader* reader, size_t nbits) {
+  size_t start = reader->bp >> 3u;
+  size_t size = reader->size;
+  if(start + 1u < size) {
+    reader->buffer = (unsigned)(reader->data[start + 0]) | (unsigned)(reader->data[start + 1] << 8u);
+    reader->buffer >>= (reader->bp & 7u);
+    return 1;
+  } else {
+    reader->buffer = 0;
+    if(start + 0u < size) reader->buffer |= reader->data[start + 0];
+    reader->buffer >>= (reader->bp & 7u);
+    return reader->bp + nbits < reader->bitsize;
+  }
+}
+
+/*See ensureBits documentation above. This one ensures up to 17 bits */
+static unsigned ensureBits17(LodePNGBitReader* reader, size_t nbits) {
+  size_t start = reader->bp >> 3u;
+  size_t size = reader->size;
+  if(start + 2u < size) {
+    reader->buffer = (unsigned)(reader->data[start + 0]) | (unsigned)(reader->data[start + 1] << 8u) |
+                     (unsigned)(reader->data[start + 2] << 16u);
+    reader->buffer >>= (reader->bp & 7u);
+    return 1;
+  } else {
+    reader->buffer = 0;
+    if(start + 0u < size) reader->buffer |= reader->data[start + 0];
+    if(start + 1u < size) reader->buffer |= (unsigned)(reader->data[start + 1] << 8u);
+    reader->buffer >>= (reader->bp & 7u);
+    return reader->bp + nbits < reader->bitsize;
+  }
+}
+
+/*See ensureBits documentation above. This one ensures up to 25 bits */
+static LODEPNG_INLINE unsigned ensureBits25(LodePNGBitReader* reader, size_t nbits) {
+  size_t start = reader->bp >> 3u;
+  size_t size = reader->size;
+  if(start + 3u < size) {
+    reader->buffer = (unsigned)(reader->data[start + 0]) | (unsigned)(reader->data[start + 1] << 8u) |
+                     (unsigned)(reader->data[start + 2] << 16u) | (unsigned)(reader->data[start + 3] << 24u);
+    reader->buffer >>= (reader->bp & 7u);
+    return 1;
+  } else {
+    reader->buffer = 0;
+    if(start + 0u < size) reader->buffer |= reader->data[start + 0];
+    if(start + 1u < size) reader->buffer |= (unsigned)(reader->data[start + 1] << 8u);
+    if(start + 2u < size) reader->buffer |= (unsigned)(reader->data[start + 2] << 16u);
+    reader->buffer >>= (reader->bp & 7u);
+    return reader->bp + nbits < reader->bitsize;
+  }
+}
+
+/*See ensureBits documentation above. This one ensures up to 32 bits */
+static LODEPNG_INLINE unsigned ensureBits32(LodePNGBitReader* reader, size_t nbits) {
+  size_t start = reader->bp >> 3u;
+  size_t size = reader->size;
+  if(start + 4u < size) {
+    reader->buffer = (unsigned)(reader->data[start + 0]) | (unsigned)(reader->data[start + 1] << 8u) |
+                     (unsigned)(reader->data[start + 2] << 16u) | (unsigned)(reader->data[start + 3] << 24u);
+    reader->buffer >>= (reader->bp & 7u);
+    reader->buffer |= ((unsigned)(reader->data[start + 4] << 24u) << (7u - (reader->bp & 7u)));
+    return 1;
+  } else {
+    reader->buffer = 0;
+    if(start + 0u < size) reader->buffer |= reader->data[start + 0];
+    if(start + 1u < size) reader->buffer |= (unsigned)(reader->data[start + 1] << 8u);
+    if(start + 2u < size) reader->buffer |= (unsigned)(reader->data[start + 2] << 16u);
+    if(start + 3u < size) reader->buffer |= (unsigned)(reader->data[start + 3] << 24u);
+    reader->buffer >>= (reader->bp & 7u);
+    return reader->bp + nbits < reader->bitsize;
   }
+}
+
+/* Get bits without advancing the bit pointer. Must have enough bits available with ensureBits */
+static unsigned peekBits(LodePNGBitReader* reader, size_t nbits) {
+  return reader->buffer & ((1u << nbits) - 1u);
+}
+
+/* Must have enough bits available with ensureBits */
+static void advanceBits(LodePNGBitReader* reader, size_t nbits) {
+  reader->buffer >>= nbits;
+  reader->bp += nbits;
+}
+
+/* Must have enough bits available with ensureBits */
+static unsigned readBits(LodePNGBitReader* reader, size_t nbits) {
+  unsigned result = peekBits(reader, nbits);
+  advanceBits(reader, nbits);
   return result;
 }
 #endif /*LODEPNG_COMPILE_DECODER*/
 
+static unsigned reverseBits(unsigned bits, unsigned num) {
+  /*TODO: implement faster lookup table based version when needed*/
+  unsigned i, result = 0;
+  for(i = 0; i < num; i++) result |= ((bits >> (num - i - 1u)) & 1u) << i;
+  return result;
+}
+
 /* ////////////////////////////////////////////////////////////////////////// */
 /* / Deflate - Huffman                                                      / */
 /* ////////////////////////////////////////////////////////////////////////// */
@@ -506,98 +665,125 @@ static const unsigned CLCL_ORDER[NUM_CODE_LENGTH_CODES]
 /*
 Huffman tree struct, containing multiple representations of the tree
 */
-typedef struct HuffmanTree
-{
-  unsigned* tree2d;
-  unsigned* tree1d;
-  unsigned* lengths; /*the lengths of the codes of the 1d-tree*/
+typedef struct HuffmanTree {
+  unsigned* codes; /*the huffman codes (bit patterns representing the symbols)*/
+  unsigned* lengths; /*the lengths of the huffman codes*/
   unsigned maxbitlen; /*maximum number of bits a single code can get*/
   unsigned numcodes; /*number of symbols in the alphabet = number of codes*/
+  /* for reading only */
+  unsigned char* table_len; /*length of symbol from lookup table, or max length if secondary lookup needed*/
+  unsigned short* table_value; /*value of symbol from lookup table, or pointer to secondary table if needed*/
 } HuffmanTree;
 
-/*function used for debug purposes to draw the tree in ascii art with C++*/
-/*
-static void HuffmanTree_draw(HuffmanTree* tree)
-{
-  std::cout << "tree. length: " << tree->numcodes << " maxbitlen: " << tree->maxbitlen << std::endl;
-  for(size_t i = 0; i != tree->tree1d.size; ++i)
-  {
-    if(tree->lengths.data[i])
-      std::cout << i << " " << tree->tree1d.data[i] << " " << tree->lengths.data[i] << std::endl;
-  }
-  std::cout << std::endl;
-}*/
-
-static void HuffmanTree_init(HuffmanTree* tree)
-{
-  tree->tree2d = 0;
-  tree->tree1d = 0;
+static void HuffmanTree_init(HuffmanTree* tree) {
+  tree->codes = 0;
   tree->lengths = 0;
+  tree->table_len = 0;
+  tree->table_value = 0;
 }
 
-static void HuffmanTree_cleanup(HuffmanTree* tree)
-{
-  lodepng_free(tree->tree2d);
-  lodepng_free(tree->tree1d);
+static void HuffmanTree_cleanup(HuffmanTree* tree) {
+  lodepng_free(tree->codes);
   lodepng_free(tree->lengths);
-}
-
-/*the tree representation used by the decoder. return value is error*/
-static unsigned HuffmanTree_make2DTree(HuffmanTree* tree)
-{
-  unsigned nodefilled = 0; /*up to which node it is filled*/
-  unsigned treepos = 0; /*position in the tree (1 of the numcodes columns)*/
-  unsigned n, i;
-
-  tree->tree2d = (unsigned*)lodepng_malloc(tree->numcodes * 2 * sizeof(unsigned));
-  if(!tree->tree2d) return 83; /*alloc fail*/
-
-  /*
-  convert tree1d[] to tree2d[][]. In the 2D array, a value of 32767 means
-  uninited, a value >= numcodes is an address to another bit, a value < numcodes
-  is a code. The 2 rows are the 2 possible bit values (0 or 1), there are as
-  many columns as codes - 1.
-  A good huffman tree has N * 2 - 1 nodes, of which N - 1 are internal nodes.
-  Here, the internal nodes are stored (what their 0 and 1 option point to).
-  There is only memory for such good tree currently, if there are more nodes
-  (due to too long length codes), error 55 will happen
-  */
-  for(n = 0; n < tree->numcodes * 2; ++n)
-  {
-    tree->tree2d[n] = 32767; /*32767 here means the tree2d isn't filled there yet*/
-  }
-
-  for(n = 0; n < tree->numcodes; ++n) /*the codes*/
-  {
-    for(i = 0; i != tree->lengths[n]; ++i) /*the bits for this code*/
-    {
-      unsigned char bit = (unsigned char)((tree->tree1d[n] >> (tree->lengths[n] - i - 1)) & 1);
-      /*oversubscribed, see comment in lodepng_error_text*/
-      if(treepos > 2147483647 || treepos + 2 > tree->numcodes) return 55;
-      if(tree->tree2d[2 * treepos + bit] == 32767) /*not yet filled in*/
-      {
-        if(i + 1 == tree->lengths[n]) /*last bit*/
-        {
-          tree->tree2d[2 * treepos + bit] = n; /*put the current code in it*/
-          treepos = 0;
-        }
-        else
-        {
-          /*put address of the next step in here, first that address has to be found of course
-          (it's just nodefilled + 1)...*/
-          ++nodefilled;
-          /*addresses encoded with numcodes added to it*/
-          tree->tree2d[2 * treepos + bit] = nodefilled + tree->numcodes;
-          treepos = nodefilled;
-        }
+  lodepng_free(tree->table_len);
+  lodepng_free(tree->table_value);
+}
+
+/* amount of bits for first huffman table lookup (aka root bits), see HuffmanTree_makeTable and huffmanDecodeSymbol.*/
+/* values 8u and 9u work the fastest */
+#define FIRSTBITS 9u
+
+/* make table for huffman decoding */
+static unsigned HuffmanTree_makeTable(HuffmanTree* tree) {
+  static const unsigned headsize = 1u << FIRSTBITS; /*size of the first table*/
+  static const unsigned mask = (1u << FIRSTBITS) /*headsize*/ - 1u;
+  size_t i, pointer, size; /*total table size*/
+  unsigned* maxlens = (unsigned*)lodepng_malloc(headsize * sizeof(unsigned));
+  if(!maxlens) return 83; /*alloc fail*/
+
+  /* compute maxlens: max total bit length of symbols sharing prefix in the first table*/
+  for(i = 0; i < headsize; ++i) maxlens[i] = 0;
+  for(i = 0; i < tree->numcodes; i++) {
+    unsigned symbol = tree->codes[i];
+    unsigned l = tree->lengths[i];
+    unsigned index;
+    if(l <= FIRSTBITS) continue; /*symbols that fit in first table don't increase secondary table size*/
+    /*get the FIRSTBITS MSBs, the MSBs of the symbol are encoded first. See later comment about the reversing*/
+    index = reverseBits(symbol >> (l - FIRSTBITS), FIRSTBITS);
+    maxlens[index] = LODEPNG_MAX(maxlens[index], l);
+  }
+  /* compute total table size: size of first table plus all secondary tables for symbols longer than FIRSTBITS */
+  size = headsize;
+  for(i = 0; i < headsize; ++i) {
+    unsigned l = maxlens[i];
+    if(l > FIRSTBITS) size += (1u << (l - FIRSTBITS));
+  }
+  tree->table_len = (unsigned char*)lodepng_malloc(size * sizeof(*tree->table_len));
+  tree->table_value = (unsigned short*)lodepng_malloc(size * sizeof(*tree->table_value));
+  if(!tree->table_len || !tree->table_value) {
+    lodepng_free(maxlens);
+    /* freeing tree->table values is done at a higher scope */
+    return 83; /*alloc fail*/
+  }
+  /*initialize with an invalid length to indicate unused entries*/
+  for(i = 0; i < size; ++i) tree->table_len[i] = 16;
+
+  /*fill in the first table for long symbols: max prefix size and pointer to secondary tables*/
+  pointer = headsize;
+  for(i = 0; i < headsize; ++i) {
+    unsigned l = maxlens[i];
+    if(l <= FIRSTBITS) continue;
+    tree->table_len[i] = l;
+    tree->table_value[i] = pointer;
+    pointer += (1u << (l - FIRSTBITS));
+  }
+  lodepng_free(maxlens);
+
+  /*fill in the first table for short symbols, or secondary table for long symbols*/
+  for(i = 0; i < tree->numcodes; ++i) {
+    unsigned l = tree->lengths[i];
+    unsigned symbol = tree->codes[i]; /*the huffman bit pattern. i itself is the value.*/
+    /*reverse bits, because the huffman bits are given in MSB first order but the bit reader reads LSB first*/
+    unsigned reverse = reverseBits(symbol, l);
+    if(l == 0) {
+      continue;
+    } else if(l <= FIRSTBITS) {
+      /*short symbol, fully in first table, replicated num times if l < FIRSTBITS*/
+      unsigned num = 1u << (FIRSTBITS - l);
+      unsigned j;
+      for(j = 0; j < num; ++j) {
+        /*bit reader will read the l bits of symbol first, the remaining FIRSTBITS - l bits go to the MSB's*/
+        unsigned index = reverse | (j << l);
+        if(tree->table_len[index] != 16) return 55; /*invalid tree: long symbol shares prefix with short symbol*/
+        tree->table_len[index] = l;
+        tree->table_value[index] = i;
+      }
+    } else {
+      /*long symbol, shares prefix with other long symbols in first lookup table, needs second lookup*/
+      /*the FIRSTBITS MSBs of the symbol are the first table index*/
+      unsigned index = reverse & mask;
+      unsigned maxlen = tree->table_len[index];
+      /*log2 of secondary table length, should be >= l - FIRSTBITS*/
+      unsigned tablelen = maxlen - FIRSTBITS;
+      unsigned start = tree->table_value[index]; /*starting index in secondary table*/
+      unsigned num = 1u << (tablelen - (l - FIRSTBITS)); /*amount of entries of this symbol in secondary table*/
+      unsigned j;
+      if(maxlen < l) return 55; /*invalid tree: long symbol shares prefix with short symbol*/
+      for(j = 0; j < num; ++j) {
+        unsigned reverse2 = reverse >> FIRSTBITS; /* l - FIRSTBITS bits */
+        unsigned index2 = start + (reverse2 | (j << (l - FIRSTBITS)));
+        tree->table_len[index2] = l;
+        tree->table_value[index2] = i;
       }
-      else treepos = tree->tree2d[2 * treepos + bit] - tree->numcodes;
     }
   }
 
-  for(n = 0; n < tree->numcodes * 2; ++n)
-  {
-    if(tree->tree2d[n] == 32767) tree->tree2d[n] = 0; /*remove possible remaining 32767's*/
+  /* A good huffman tree has N * 2 - 1 nodes, of which N - 1 are internal nodes.
+  If that is not the case (due to too long length codes), the table will not
+  have been fully used, and this is an error (not all bit combinations can be
+  decoded): an oversubscribed huffman tree, indicated by error 55. */
+  for(i = 0; i < size; ++i) {
+    if(tree->table_len[i] == 16) return 55;
   }
 
   return 0;
@@ -608,44 +794,40 @@ Second step for the ...makeFromLengths and ...makeFromFrequencies functions.
 numcodes, lengths and maxbitlen must already be filled in correctly. return
 value is error.
 */
-static unsigned HuffmanTree_makeFromLengths2(HuffmanTree* tree)
-{
-  uivector blcount;
-  uivector nextcode;
+static unsigned HuffmanTree_makeFromLengths2(HuffmanTree* tree) {
+  unsigned* blcount;
+  unsigned* nextcode;
   unsigned error = 0;
   unsigned bits, n;
 
-  uivector_init(&blcount);
-  uivector_init(&nextcode);
-
-  tree->tree1d = (unsigned*)lodepng_malloc(tree->numcodes * sizeof(unsigned));
-  if(!tree->tree1d) error = 83; /*alloc fail*/
+  tree->codes = (unsigned*)lodepng_malloc(tree->numcodes * sizeof(unsigned));
+  blcount = (unsigned*)lodepng_malloc((tree->maxbitlen + 1) * sizeof(unsigned));
+  nextcode = (unsigned*)lodepng_malloc((tree->maxbitlen + 1) * sizeof(unsigned));
+  if(!tree->codes || !blcount || !nextcode) error = 83; /*alloc fail*/
 
-  if(!uivector_resizev(&blcount, tree->maxbitlen + 1, 0)
-  || !uivector_resizev(&nextcode, tree->maxbitlen + 1, 0))
-    error = 83; /*alloc fail*/
-
-  if(!error)
-  {
+  if(!error) {
+    for(n = 0; n != tree->maxbitlen + 1; n++) blcount[n] = nextcode[n] = 0;
     /*step 1: count number of instances of each code length*/
-    for(bits = 0; bits != tree->numcodes; ++bits) ++blcount.data[tree->lengths[bits]];
+    for(bits = 0; bits != tree->numcodes; ++bits) ++blcount[tree->lengths[bits]];
     /*step 2: generate the nextcode values*/
-    for(bits = 1; bits <= tree->maxbitlen; ++bits)
-    {
-      nextcode.data[bits] = (nextcode.data[bits - 1] + blcount.data[bits - 1]) << 1;
+    for(bits = 1; bits <= tree->maxbitlen; ++bits) {
+      nextcode[bits] = (nextcode[bits - 1] + blcount[bits - 1]) << 1;
     }
     /*step 3: generate all the codes*/
-    for(n = 0; n != tree->numcodes; ++n)
-    {
-      if(tree->lengths[n] != 0) tree->tree1d[n] = nextcode.data[tree->lengths[n]]++;
+    for(n = 0; n != tree->numcodes; ++n) {
+      if(tree->lengths[n] != 0) {
+        tree->codes[n] = nextcode[tree->lengths[n]]++;
+        /*remove superfluous bits from the code*/
+        tree->codes[n] &= ((1u << tree->lengths[n]) - 1u);
+      }
     }
   }
 
-  uivector_cleanup(&blcount);
-  uivector_cleanup(&nextcode);
+  lodepng_free(blcount);
+  lodepng_free(nextcode);
 
-  if(!error) return HuffmanTree_make2DTree(tree);
-  else return error;
+  if(!error) error = HuffmanTree_makeTable(tree);
+  return error;
 }
 
 /*
@@ -654,8 +836,7 @@ by Deflate. maxbitlen is the maximum bits that a code in the tree can have.
 return value is error.
 */
 static unsigned HuffmanTree_makeFromLengths(HuffmanTree* tree, const unsigned* bitlen,
-                                            size_t numcodes, unsigned maxbitlen)
-{
+                                            size_t numcodes, unsigned maxbitlen) {
   unsigned i;
   tree->lengths = (unsigned*)lodepng_malloc(numcodes * sizeof(unsigned));
   if(!tree->lengths) return 83; /*alloc fail*/
@@ -671,8 +852,7 @@ static unsigned HuffmanTree_makeFromLengths(HuffmanTree* tree, const unsigned* b
 Jyrki Katajainen, Alistair Moffat, Andrew Turpin, 1995.*/
 
 /*chain node for boundary package merge*/
-typedef struct BPMNode
-{
+typedef struct BPMNode {
   int weight; /*the sum of all weights in this chain*/
   unsigned index; /*index of this leaf node (called "count" in the paper)*/
   struct BPMNode* tail; /*the next nodes in this chain (null if last)*/
@@ -680,8 +860,7 @@ typedef struct BPMNode
 } BPMNode;
 
 /*lists of chains*/
-typedef struct BPMLists
-{
+typedef struct BPMLists {
   /*memory pool*/
   unsigned memsize;
   BPMNode* memory;
@@ -695,26 +874,22 @@ typedef struct BPMLists
 } BPMLists;
 
 /*creates a new chain node with the given parameters, from the memory in the lists */
-static BPMNode* bpmnode_create(BPMLists* lists, int weight, unsigned index, BPMNode* tail)
-{
+static BPMNode* bpmnode_create(BPMLists* lists, int weight, unsigned index, BPMNode* tail) {
   unsigned i;
   BPMNode* result;
 
   /*memory full, so garbage collect*/
-  if(lists->nextfree >= lists->numfree)
-  {
+  if(lists->nextfree >= lists->numfree) {
     /*mark only those that are in use*/
     for(i = 0; i != lists->memsize; ++i) lists->memory[i].in_use = 0;
-    for(i = 0; i != lists->listsize; ++i)
-    {
+    for(i = 0; i != lists->listsize; ++i) {
       BPMNode* node;
       for(node = lists->chains0[i]; node != 0; node = node->tail) node->in_use = 1;
       for(node = lists->chains1[i]; node != 0; node = node->tail) node->in_use = 1;
     }
     /*collect those that are free*/
     lists->numfree = 0;
-    for(i = 0; i != lists->memsize; ++i)
-    {
+    for(i = 0; i != lists->memsize; ++i) {
       if(!lists->memory[i].in_use) lists->freelist[lists->numfree++] = &lists->memory[i];
     }
     lists->nextfree = 0;
@@ -727,42 +902,49 @@ static BPMNode* bpmnode_create(BPMLists* lists, int weight, unsigned index, BPMN
   return result;
 }
 
-static int bpmnode_compare(const void* a, const void* b)
-{
-  int wa = ((const BPMNode*)a)->weight;
-  int wb = ((const BPMNode*)b)->weight;
-  if(wa < wb) return -1;
-  if(wa > wb) return 1;
-  /*make the qsort a stable sort*/
-  return ((const BPMNode*)a)->index < ((const BPMNode*)b)->index ? 1 : -1;
+/*sort the leaves with stable mergesort*/
+static void bpmnode_sort(BPMNode* leaves, size_t num) {
+  BPMNode* mem = (BPMNode*)lodepng_malloc(sizeof(*leaves) * num);
+  size_t width, counter = 0;
+  for(width = 1; width < num; width *= 2) {
+    BPMNode* a = (counter & 1) ? mem : leaves;
+    BPMNode* b = (counter & 1) ? leaves : mem;
+    size_t p;
+    for(p = 0; p < num; p += 2 * width) {
+      size_t q = (p + width > num) ? num : (p + width);
+      size_t r = (p + 2 * width > num) ? num : (p + 2 * width);
+      size_t i = p, j = q, k;
+      for(k = p; k < r; k++) {
+        if(i < q && (j >= r || a[i].weight <= a[j].weight)) b[k] = a[i++];
+        else b[k] = a[j++];
+      }
+    }
+    counter++;
+  }
+  if(counter & 1) lodepng_memcpy(leaves, mem, sizeof(*leaves) * num);
+  lodepng_free(mem);
 }
 
 /*Boundary Package Merge step, numpresent is the amount of leaves, and c is the current chain.*/
-static void boundaryPM(BPMLists* lists, BPMNode* leaves, size_t numpresent, int c, int num)
-{
+static void boundaryPM(BPMLists* lists, BPMNode* leaves, size_t numpresent, int c, int num) {
   unsigned lastindex = lists->chains1[c]->index;
 
-  if(c == 0)
-  {
+  if(c == 0) {
     if(lastindex >= numpresent) return;
     lists->chains0[c] = lists->chains1[c];
     lists->chains1[c] = bpmnode_create(lists, leaves[lastindex].weight, lastindex + 1, 0);
-  }
-  else
-  {
+  } else {
     /*sum of the weights of the head nodes of the previous lookahead chains.*/
     int sum = lists->chains0[c - 1]->weight + lists->chains1[c - 1]->weight;
     lists->chains0[c] = lists->chains1[c];
-    if(lastindex < numpresent && sum > leaves[lastindex].weight)
-    {
+    if(lastindex < numpresent && sum > leaves[lastindex].weight) {
       lists->chains1[c] = bpmnode_create(lists, leaves[lastindex].weight, lastindex + 1, lists->chains1[c]->tail);
       return;
     }
     lists->chains1[c] = bpmnode_create(lists, sum, lastindex, lists->chains1[c - 1]);
     /*in the end we are only interested in the chain of the last list, so no
     need to recurse if we're at the last one (this gives measurable speedup)*/
-    if(num + 1 < (int)(2 * numpresent - 2))
-    {
+    if(num + 1 < (int)(2 * numpresent - 2)) {
       boundaryPM(lists, leaves, numpresent, c - 1, num);
       boundaryPM(lists, leaves, numpresent, c - 1, num);
     }
@@ -770,23 +952,20 @@ static void boundaryPM(BPMLists* lists, BPMNode* leaves, size_t numpresent, int
 }
 
 unsigned lodepng_huffman_code_lengths(unsigned* lengths, const unsigned* frequencies,
-                                      size_t numcodes, unsigned maxbitlen)
-{
+                                      size_t numcodes, unsigned maxbitlen) {
   unsigned error = 0;
   unsigned i;
   size_t numpresent = 0; /*number of symbols with non-zero frequency*/
   BPMNode* leaves; /*the symbols, only those with > 0 frequency*/
 
   if(numcodes == 0) return 80; /*error: a tree of 0 symbols is not supposed to be made*/
-  if((1u << maxbitlen) < numcodes) return 80; /*error: represent all symbols*/
+  if((1u << maxbitlen) < (unsigned)numcodes) return 80; /*error: represent all symbols*/
 
   leaves = (BPMNode*)lodepng_malloc(numcodes * sizeof(*leaves));
   if(!leaves) return 83; /*alloc fail*/
 
-  for(i = 0; i != numcodes; ++i)
-  {
-    if(frequencies[i] > 0)
-    {
+  for(i = 0; i != numcodes; ++i) {
+    if(frequencies[i] > 0) {
       leaves[numpresent].weight = (int)frequencies[i];
       leaves[numpresent].index = i;
       ++numpresent;
@@ -799,22 +978,17 @@ unsigned lodepng_huffman_code_lengths(unsigned* lengths, const unsigned* frequen
   according to RFC 1951 section 3.2.7. Some decoders incorrectly require two. To
   make these work as well ensure there are at least two symbols. The
   Package-Merge code below also doesn't work correctly if there's only one
-  symbol, it'd give it the theoritical 0 bits but in practice zlib wants 1 bit*/
-  if(numpresent == 0)
-  {
+  symbol, it'd give it the theoretical 0 bits but in practice zlib wants 1 bit*/
+  if(numpresent == 0) {
     lengths[0] = lengths[1] = 1; /*note that for RFC 1951 section 3.2.7, only lengths[0] = 1 is needed*/
-  }
-  else if(numpresent == 1)
-  {
+  } else if(numpresent == 1) {
     lengths[leaves[0].index] = 1;
     lengths[leaves[0].index == 0 ? 1 : 0] = 1;
-  }
-  else
-  {
+  } else {
     BPMLists lists;
     BPMNode* node;
 
-    qsort(leaves, numpresent, sizeof(BPMNode), bpmnode_compare);
+    bpmnode_sort(leaves, numpresent);
 
     lists.listsize = maxbitlen;
     lists.memsize = 2 * maxbitlen * (maxbitlen + 1);
@@ -826,15 +1000,13 @@ unsigned lodepng_huffman_code_lengths(unsigned* lengths, const unsigned* frequen
     lists.chains1 = (BPMNode**)lodepng_malloc(lists.listsize * sizeof(BPMNode*));
     if(!lists.memory || !lists.freelist || !lists.chains0 || !lists.chains1) error = 83; /*alloc fail*/
 
-    if(!error)
-    {
+    if(!error) {
       for(i = 0; i != lists.memsize; ++i) lists.freelist[i] = &lists.memory[i];
 
       bpmnode_create(&lists, leaves[0].weight, 1, 0);
       bpmnode_create(&lists, leaves[1].weight, 2, 0);
 
-      for(i = 0; i != lists.listsize; ++i)
-      {
+      for(i = 0; i != lists.listsize; ++i) {
         lists.chains0[i] = &lists.memory[0];
         lists.chains1[i] = &lists.memory[1];
       }
@@ -842,8 +1014,7 @@ unsigned lodepng_huffman_code_lengths(unsigned* lengths, const unsigned* frequen
       /*each boundaryPM call adds one chain to the last list, and we need 2 * numpresent - 2 chains.*/
       for(i = 2; i != 2 * numpresent - 2; ++i) boundaryPM(&lists, leaves, numpresent, (int)maxbitlen - 1, (int)i);
 
-      for(node = lists.chains1[maxbitlen - 1]; node; node = node->tail)
-      {
+      for(node = lists.chains1[maxbitlen - 1]; node; node = node->tail) {
         for(i = 0; i != node->index; ++i) ++lengths[leaves[i].index];
       }
     }
@@ -860,8 +1031,8 @@ unsigned lodepng_huffman_code_lengths(unsigned* lengths, const unsigned* frequen
 
 /*Create the Huffman tree given the symbol frequencies*/
 static unsigned HuffmanTree_makeFromFrequencies(HuffmanTree* tree, const unsigned* frequencies,
-                                                size_t mincodes, size_t numcodes, unsigned maxbitlen)
-{
+                                                size_t mincodes, size_t numcodes, unsigned maxbitlen) {
+  size_t i;
   unsigned error = 0;
   while(!frequencies[numcodes - 1] && numcodes > mincodes) --numcodes; /*trim zeroes*/
   tree->maxbitlen = maxbitlen;
@@ -869,27 +1040,24 @@ static unsigned HuffmanTree_makeFromFrequencies(HuffmanTree* tree, const unsigne
   tree->lengths = (unsigned*)lodepng_realloc(tree->lengths, numcodes * sizeof(unsigned));
   if(!tree->lengths) return 83; /*alloc fail*/
   /*initialize all lengths to 0*/
-  memset(tree->lengths, 0, numcodes * sizeof(unsigned));
+  for(i = 0; i < numcodes; i++) tree->lengths[i] = 0;
 
   error = lodepng_huffman_code_lengths(tree->lengths, frequencies, numcodes, maxbitlen);
   if(!error) error = HuffmanTree_makeFromLengths2(tree);
   return error;
 }
 
-static unsigned HuffmanTree_getCode(const HuffmanTree* tree, unsigned index)
-{
-  return tree->tree1d[index];
+static unsigned HuffmanTree_getCode(const HuffmanTree* tree, unsigned index) {
+  return tree->codes[index];
 }
 
-static unsigned HuffmanTree_getLength(const HuffmanTree* tree, unsigned index)
-{
+static unsigned HuffmanTree_getLength(const HuffmanTree* tree, unsigned index) {
   return tree->lengths[index];
 }
 #endif /*LODEPNG_COMPILE_ENCODER*/
 
 /*get the literal and length code tree of a deflated block with fixed tree, as per the deflate specification*/
-static unsigned generateFixedLitLenTree(HuffmanTree* tree)
-{
+static unsigned generateFixedLitLenTree(HuffmanTree* tree) {
   unsigned i, error = 0;
   unsigned* bitlen = (unsigned*)lodepng_malloc(NUM_DEFLATE_CODE_SYMBOLS * sizeof(unsigned));
   if(!bitlen) return 83; /*alloc fail*/
@@ -907,8 +1075,7 @@ static unsigned generateFixedLitLenTree(HuffmanTree* tree)
 }
 
 /*get the distance code tree of a deflated block with fixed tree, as specified in the deflate specification*/
-static unsigned generateFixedDistanceTree(HuffmanTree* tree)
-{
+static unsigned generateFixedDistanceTree(HuffmanTree* tree) {
   unsigned i, error = 0;
   unsigned* bitlen = (unsigned*)lodepng_malloc(NUM_DISTANCE_SYMBOLS * sizeof(unsigned));
   if(!bitlen) return 83; /*alloc fail*/
@@ -924,26 +1091,21 @@ static unsigned generateFixedDistanceTree(HuffmanTree* tree)
 #ifdef LODEPNG_COMPILE_DECODER
 
 /*
-returns the code, or (unsigned)(-1) if error happened
-inbitlength is the length of the complete buffer, in bits (so its byte length times 8)
+returns the code. The bit reader must already have been ensured at least 15 bits
 */
-static unsigned huffmanDecodeSymbol(const unsigned char* in, size_t* bp,
-                                    const HuffmanTree* codetree, size_t inbitlength)
-{
-  unsigned treepos = 0, ct;
-  for(;;)
-  {
-    if(*bp >= inbitlength) return (unsigned)(-1); /*error: end of input memory reached without endcode*/
-    /*
-    decode the symbol from the tree. The "readBitFromStream" code is inlined in
-    the expression below because this is the biggest bottleneck while decoding
-    */
-    ct = codetree->tree2d[(treepos << 1) + READBIT(*bp, in)];
-    ++(*bp);
-    if(ct < codetree->numcodes) return ct; /*the symbol is decoded, return it*/
-    else treepos = ct - codetree->numcodes; /*symbol not yet decoded, instead move tree position*/
-
-    if(treepos >= codetree->numcodes) return (unsigned)(-1); /*error: it appeared outside the codetree*/
+static unsigned huffmanDecodeSymbol(LodePNGBitReader* reader, const HuffmanTree* codetree) {
+  unsigned short code = peekBits(reader, FIRSTBITS);
+  unsigned short l = codetree->table_len[code];
+  unsigned short value = codetree->table_value[code];
+  if(l <= FIRSTBITS) {
+    advanceBits(reader, l);
+    return value;
+  } else {
+    unsigned index2;
+    advanceBits(reader, FIRSTBITS);
+    index2 = value + peekBits(reader, l - FIRSTBITS);
+    advanceBits(reader, codetree->table_len[index2] - FIRSTBITS);
+    return codetree->table_value[index2];
   }
 }
 #endif /*LODEPNG_COMPILE_DECODER*/
@@ -955,8 +1117,7 @@ static unsigned huffmanDecodeSymbol(const unsigned char* in, size_t* bp,
 /* ////////////////////////////////////////////////////////////////////////// */
 
 /*get the tree of a deflated block with fixed tree, as specified in the deflate specification*/
-static void getTreeInflateFixed(HuffmanTree* tree_ll, HuffmanTree* tree_d)
-{
+static void getTreeInflateFixed(HuffmanTree* tree_ll, HuffmanTree* tree_d) {
   /*TODO: check for out of memory errors*/
   generateFixedLitLenTree(tree_ll);
   generateFixedDistanceTree(tree_d);
@@ -964,12 +1125,10 @@ static void getTreeInflateFixed(HuffmanTree* tree_ll, HuffmanTree* tree_d)
 
 /*get the tree of a deflated block with dynamic tree, the tree itself is also Huffman compressed with a known tree*/
 static unsigned getTreeInflateDynamic(HuffmanTree* tree_ll, HuffmanTree* tree_d,
-                                      const unsigned char* in, size_t* bp, size_t inlength)
-{
+                                      LodePNGBitReader* reader) {
   /*make sure that length values that aren't filled in will be 0, or a wrong tree will be generated*/
   unsigned error = 0;
   unsigned n, HLIT, HDIST, HCLEN, i;
-  size_t inbitlength = inlength * 8;
 
   /*see comments in deflateDynamic for explanation of the context and these variables, it is analogous*/
   unsigned* bitlen_ll = 0; /*lit,len code lengths*/
@@ -978,30 +1137,31 @@ static unsigned getTreeInflateDynamic(HuffmanTree* tree_ll, HuffmanTree* tree_d,
   unsigned* bitlen_cl = 0;
   HuffmanTree tree_cl; /*the code tree for code length codes (the huffman tree for compressed huffman trees)*/
 
-  if((*bp) + 14 > (inlength << 3)) return 49; /*error: the bit pointer is or will go past the memory*/
+  if(!ensureBits17(reader, 14)) return 49; /*error: the bit pointer is or will go past the memory*/
 
   /*number of literal/length codes + 257. Unlike the spec, the value 257 is added to it here already*/
-  HLIT =  readBitsFromStream(bp, in, 5) + 257;
+  HLIT =  readBits(reader, 5) + 257;
   /*number of distance codes. Unlike the spec, the value 1 is added to it here already*/
-  HDIST = readBitsFromStream(bp, in, 5) + 1;
+  HDIST = readBits(reader, 5) + 1;
   /*number of code length codes. Unlike the spec, the value 4 is added to it here already*/
-  HCLEN = readBitsFromStream(bp, in, 4) + 4;
+  HCLEN = readBits(reader, 4) + 4;
 
-  if((*bp) + HCLEN * 3 > (inlength << 3)) return 50; /*error: the bit pointer is or will go past the memory*/
+  bitlen_cl = (unsigned*)lodepng_malloc(NUM_CODE_LENGTH_CODES * sizeof(unsigned));
+  if(!bitlen_cl) return 83 /*alloc fail*/;
 
   HuffmanTree_init(&tree_cl);
 
-  while(!error)
-  {
+  while(!error) {
     /*read the code length codes out of 3 * (amount of code length codes) bits*/
-
-    bitlen_cl = (unsigned*)lodepng_malloc(NUM_CODE_LENGTH_CODES * sizeof(unsigned));
-    if(!bitlen_cl) ERROR_BREAK(83 /*alloc fail*/);
-
-    for(i = 0; i != NUM_CODE_LENGTH_CODES; ++i)
-    {
-      if(i < HCLEN) bitlen_cl[CLCL_ORDER[i]] = readBitsFromStream(bp, in, 3);
-      else bitlen_cl[CLCL_ORDER[i]] = 0; /*if not, it must stay 0*/
+    if(lodepng_gtofl(reader->bp, HCLEN * 3, reader->bitsize)) {
+      ERROR_BREAK(50); /*error: the bit pointer is or will go past the memory*/
+    }
+    for(i = 0; i != HCLEN; ++i) {
+      ensureBits9(reader, 3); /*out of bounds already checked above */
+      bitlen_cl[CLCL_ORDER[i]] = readBits(reader, 3);
+    }
+    for(i = HCLEN; i != NUM_CODE_LENGTH_CODES; ++i) {
+      bitlen_cl[CLCL_ORDER[i]] = 0;
     }
 
     error = HuffmanTree_makeFromLengths(&tree_cl, bitlen_cl, NUM_CODE_LENGTH_CODES, 7);
@@ -1016,78 +1176,64 @@ static unsigned getTreeInflateDynamic(HuffmanTree* tree_ll, HuffmanTree* tree_d,
 
     /*i is the current symbol we're reading in the part that contains the code lengths of lit/len and dist codes*/
     i = 0;
-    while(i < HLIT + HDIST)
-    {
-      unsigned code = huffmanDecodeSymbol(in, bp, &tree_cl, inbitlength);
-      if(code <= 15) /*a length code*/
-      {
+    while(i < HLIT + HDIST) {
+      unsigned code;
+      ensureBits25(reader, 22); /* up to 15 bits for huffman code, up to 7 extra bits below*/
+      code = huffmanDecodeSymbol(reader, &tree_cl);
+      if(code <= 15) /*a length code*/ {
         if(i < HLIT) bitlen_ll[i] = code;
         else bitlen_d[i - HLIT] = code;
         ++i;
-      }
-      else if(code == 16) /*repeat previous*/
-      {
+      } else if(code == 16) /*repeat previous*/ {
         unsigned replength = 3; /*read in the 2 bits that indicate repeat length (3-6)*/
         unsigned value; /*set value to the previous code*/
 
         if(i == 0) ERROR_BREAK(54); /*can't repeat previous if i is 0*/
 
-        if((*bp + 2) > inbitlength) ERROR_BREAK(50); /*error, bit pointer jumps past memory*/
-        replength += readBitsFromStream(bp, in, 2);
+        replength += readBits(reader, 2);
 
         if(i < HLIT + 1) value = bitlen_ll[i - 1];
         else value = bitlen_d[i - HLIT - 1];
         /*repeat this value in the next lengths*/
-        for(n = 0; n < replength; ++n)
-        {
+        for(n = 0; n < replength; ++n) {
           if(i >= HLIT + HDIST) ERROR_BREAK(13); /*error: i is larger than the amount of codes*/
           if(i < HLIT) bitlen_ll[i] = value;
           else bitlen_d[i - HLIT] = value;
           ++i;
         }
-      }
-      else if(code == 17) /*repeat "0" 3-10 times*/
-      {
+      } else if(code == 17) /*repeat "0" 3-10 times*/ {
         unsigned replength = 3; /*read in the bits that indicate repeat length*/
-        if((*bp + 3) > inbitlength) ERROR_BREAK(50); /*error, bit pointer jumps past memory*/
-        replength += readBitsFromStream(bp, in, 3);
+        replength += readBits(reader, 3);
 
         /*repeat this value in the next lengths*/
-        for(n = 0; n < replength; ++n)
-        {
+        for(n = 0; n < replength; ++n) {
           if(i >= HLIT + HDIST) ERROR_BREAK(14); /*error: i is larger than the amount of codes*/
 
           if(i < HLIT) bitlen_ll[i] = 0;
           else bitlen_d[i - HLIT] = 0;
           ++i;
         }
-      }
-      else if(code == 18) /*repeat "0" 11-138 times*/
-      {
+      } else if(code == 18) /*repeat "0" 11-138 times*/ {
         unsigned replength = 11; /*read in the bits that indicate repeat length*/
-        if((*bp + 7) > inbitlength) ERROR_BREAK(50); /*error, bit pointer jumps past memory*/
-        replength += readBitsFromStream(bp, in, 7);
+        replength += readBits(reader, 7);
 
         /*repeat this value in the next lengths*/
-        for(n = 0; n < replength; ++n)
-        {
+        for(n = 0; n < replength; ++n) {
           if(i >= HLIT + HDIST) ERROR_BREAK(15); /*error: i is larger than the amount of codes*/
 
           if(i < HLIT) bitlen_ll[i] = 0;
           else bitlen_d[i - HLIT] = 0;
           ++i;
         }
+      } else /*if(code == (unsigned)(-1))*/ /*huffmanDecodeSymbol returns (unsigned)(-1) in case of error*/ {
+        ERROR_BREAK(16); /*nonexistent code, this can never happen*/
       }
-      else /*if(code == (unsigned)(-1))*/ /*huffmanDecodeSymbol returns (unsigned)(-1) in case of error*/
-      {
-        if(code == (unsigned)(-1))
-        {
-          /*return error code 10 or 11 depending on the situation that happened in huffmanDecodeSymbol
-          (10=no endcode, 11=wrong jump outside of tree)*/
-          error = (*bp) > inbitlength ? 10 : 11;
-        }
-        else error = 16; /*unexisting code, this can never happen*/
-        break;
+      /*check if any of the ensureBits above went out of bounds*/
+      if(reader->bp > reader->bitsize) {
+        /*return error code 10 or 11 depending on the situation that happened in huffmanDecodeSymbol
+        (10=no endcode, 11=wrong jump outside of tree)*/
+        /* TODO: revise error codes 10,11,50: the above comment is no longer valid */
+        ERROR_BREAK(50); /*error, bit pointer jumps past memory*/
       }
     }
     if(error) break;
@@ -1110,65 +1256,64 @@ static unsigned getTreeInflateDynamic(HuffmanTree* tree_ll, HuffmanTree* tree_d,
   return error;
 }
 
-/*inflate a block with dynamic of fixed Huffman tree*/
-static unsigned inflateHuffmanBlock(ucvector* out, const unsigned char* in, size_t* bp,
-                                    size_t* pos, size_t inlength, unsigned btype)
-{
+/*inflate a block with dynamic of fixed Huffman tree. btype must be 1 or 2.*/
+static unsigned inflateHuffmanBlock(ucvector* out, size_t* pos, LodePNGBitReader* reader,
+                                    unsigned btype) {
   unsigned error = 0;
   HuffmanTree tree_ll; /*the huffman tree for literal and length codes*/
   HuffmanTree tree_d; /*the huffman tree for distance codes*/
-  size_t inbitlength = inlength * 8;
 
   HuffmanTree_init(&tree_ll);
   HuffmanTree_init(&tree_d);
 
   if(btype == 1) getTreeInflateFixed(&tree_ll, &tree_d);
-  else if(btype == 2) error = getTreeInflateDynamic(&tree_ll, &tree_d, in, bp, inlength);
+  else /*if(btype == 2)*/ error = getTreeInflateDynamic(&tree_ll, &tree_d, reader);
 
-  while(!error) /*decode all symbols until end reached, breaks at end code*/
-  {
+  while(!error) /*decode all symbols until end reached, breaks at end code*/ {
     /*code_ll is literal, length or end code*/
-    unsigned code_ll = huffmanDecodeSymbol(in, bp, &tree_ll, inbitlength);
-    if(code_ll <= 255) /*literal symbol*/
-    {
+    unsigned code_ll;
+    ensureBits25(reader, 20); /* up to 15 for the huffman symbol, up to 5 for the length extra bits */
+    code_ll = huffmanDecodeSymbol(reader, &tree_ll);
+    if(code_ll <= 255) /*literal symbol*/ {
       /*ucvector_push_back would do the same, but for some reason the two lines below run 10% faster*/
       if(!ucvector_resize(out, (*pos) + 1)) ERROR_BREAK(83 /*alloc fail*/);
       out->data[*pos] = (unsigned char)code_ll;
       ++(*pos);
-    }
-    else if(code_ll >= FIRST_LENGTH_CODE_INDEX && code_ll <= LAST_LENGTH_CODE_INDEX) /*length code*/
-    {
+    } else if(code_ll >= FIRST_LENGTH_CODE_INDEX && code_ll <= LAST_LENGTH_CODE_INDEX) /*length code*/ {
       unsigned code_d, distance;
       unsigned numextrabits_l, numextrabits_d; /*extra bits for length and distance*/
-      size_t start, forward, backward, length;
+      size_t start, backward, length;
 
       /*part 1: get length base*/
       length = LENGTHBASE[code_ll - FIRST_LENGTH_CODE_INDEX];
 
       /*part 2: get extra bits and add the value of that to length*/
       numextrabits_l = LENGTHEXTRA[code_ll - FIRST_LENGTH_CODE_INDEX];
-      if((*bp + numextrabits_l) > inbitlength) ERROR_BREAK(51); /*error, bit pointer will jump past memory*/
-      length += readBitsFromStream(bp, in, numextrabits_l);
+      if(numextrabits_l != 0) {
+        /* bits already ensured above */
+        length += readBits(reader, numextrabits_l);
+      }
 
       /*part 3: get distance code*/
-      code_d = huffmanDecodeSymbol(in, bp, &tree_d, inbitlength);
-      if(code_d > 29)
-      {
-        if(code_ll == (unsigned)(-1)) /*huffmanDecodeSymbol returns (unsigned)(-1) in case of error*/
-        {
+      ensureBits32(reader, 28); /* up to 15 for the huffman symbol, up to 13 for the extra bits */
+      code_d = huffmanDecodeSymbol(reader, &tree_d);
+      if(code_d > 29) {
+        if(code_d == (unsigned)(-1)) /*huffmanDecodeSymbol returns (unsigned)(-1) in case of error*/ {
           /*return error code 10 or 11 depending on the situation that happened in huffmanDecodeSymbol
           (10=no endcode, 11=wrong jump outside of tree)*/
-          error = (*bp) > inlength * 8 ? 10 : 11;
+          ERROR_BREAK((reader->bp > reader->bitsize) ? 10 : 11);
+        } else {
+          ERROR_BREAK(18); /*error: invalid distance code (30-31 are never used)*/
         }
-        else error = 18; /*error: invalid distance code (30-31 are never used)*/
-        break;
       }
       distance = DISTANCEBASE[code_d];
 
       /*part 4: get extra bits from distance*/
       numextrabits_d = DISTANCEEXTRA[code_d];
-      if((*bp + numextrabits_d) > inbitlength) ERROR_BREAK(51); /*error, bit pointer will jump past memory*/
-      distance += readBitsFromStream(bp, in, numextrabits_d);
+      if(numextrabits_d != 0) {
+        /* bits already ensured above */
+        distance += readBits(reader, numextrabits_d);
+      }
 
       /*part 5: fill in all the out[n] values based on the length and dist*/
       start = (*pos);
@@ -1177,25 +1322,27 @@ static unsigned inflateHuffmanBlock(ucvector* out, const unsigned char* in, size
 
       if(!ucvector_resize(out, (*pos) + length)) ERROR_BREAK(83 /*alloc fail*/);
       if (distance < length) {
-        for(forward = 0; forward < length; ++forward)
-        {
+        size_t forward;
+        lodepng_memcpy(out->data + *pos, out->data + backward, distance);
+        *pos += distance;
+        for(forward = distance; forward < length; ++forward) {
           out->data[(*pos)++] = out->data[backward++];
         }
       } else {
-        memcpy(out->data + *pos, out->data + backward, length);
+        lodepng_memcpy(out->data + *pos, out->data + backward, length);
         *pos += length;
       }
-    }
-    else if(code_ll == 256)
-    {
+    } else if(code_ll == 256) {
       break; /*end code, break the loop*/
+    } else /*if(code == (unsigned)(-1))*/ /*huffmanDecodeSymbol returns (unsigned)(-1) in case of error*/ {
+      ERROR_BREAK(16) /* impossible */
     }
-    else /*if(code == (unsigned)(-1))*/ /*huffmanDecodeSymbol returns (unsigned)(-1) in case of error*/
-    {
+    /*check if any of the ensureBits above went out of bounds*/
+    if(reader->bp > reader->bitsize) {
       /*return error code 10 or 11 depending on the situation that happened in huffmanDecodeSymbol
       (10=no endcode, 11=wrong jump outside of tree)*/
-      error = ((*bp) > inlength * 8) ? 10 : 11;
-      break;
+      /* TODO: revise error codes 10,11,50: the above comment is no longer valid */
+      ERROR_BREAK(51); /*error, bit pointer jumps past memory*/
     }
   }
 
@@ -1205,57 +1352,58 @@ static unsigned inflateHuffmanBlock(ucvector* out, const unsigned char* in, size
   return error;
 }
 
-static unsigned inflateNoCompression(ucvector* out, const unsigned char* in, size_t* bp, size_t* pos, size_t inlength)
-{
-  size_t p;
-  unsigned LEN, NLEN, n, error = 0;
+static unsigned inflateNoCompression(ucvector* out, size_t* pos,
+                                     LodePNGBitReader* reader, const LodePNGDecompressSettings* settings) {
+  size_t bytepos;
+  size_t size = reader->size;
+  unsigned LEN, NLEN, error = 0;
 
   /*go to first boundary of byte*/
-  while(((*bp) & 0x7) != 0) ++(*bp);
-  p = (*bp) / 8; /*byte position*/
+  bytepos = (reader->bp + 7u) >> 3u;
 
   /*read LEN (2 bytes) and NLEN (2 bytes)*/
-  if(p + 4 >= inlength) return 52; /*error, bit pointer will jump past memory*/
-  LEN = in[p] + 256u * in[p + 1]; p += 2;
-  NLEN = in[p] + 256u * in[p + 1]; p += 2;
+  if(bytepos + 4 >= size) return 52; /*error, bit pointer will jump past memory*/
+  LEN = (unsigned)reader->data[bytepos] + (unsigned)(reader->data[bytepos + 1] << 8u); bytepos += 2;
+  NLEN = (unsigned)reader->data[bytepos] + (unsigned)(reader->data[bytepos + 1] << 8u); bytepos += 2;
 
   /*check if 16-bit NLEN is really the one's complement of LEN*/
-  if(LEN + NLEN != 65535) return 21; /*error: NLEN is not one's complement of LEN*/
+  if(!settings->ignore_nlen && LEN + NLEN != 65535) {
+    return 21; /*error: NLEN is not one's complement of LEN*/
+  }
 
   if(!ucvector_resize(out, (*pos) + LEN)) return 83; /*alloc fail*/
 
   /*read the literal data: LEN bytes are now stored in the out buffer*/
-  if(p + LEN > inlength) return 23; /*error: reading outside of in buffer*/
-  for(n = 0; n < LEN; ++n) out->data[(*pos)++] = in[p++];
+  if(bytepos + LEN > size) return 23; /*error: reading outside of in buffer*/
 
-  (*bp) = p * 8;
+  lodepng_memcpy(out->data + *pos, reader->data + bytepos, LEN);
+  *pos += LEN;
+  bytepos += LEN;
+
+  reader->bp = bytepos << 3u;
 
   return error;
 }
 
 static unsigned lodepng_inflatev(ucvector* out,
                                  const unsigned char* in, size_t insize,
-                                 const LodePNGDecompressSettings* settings)
-{
-  /*bit pointer in the "in" data, current byte is bp >> 3, current bit is bp & 0x7 (from lsb to msb of the byte)*/
-  size_t bp = 0;
+                                 const LodePNGDecompressSettings* settings) {
   unsigned BFINAL = 0;
   size_t pos = 0; /*byte position in the out buffer*/
-  unsigned error = 0;
+  LodePNGBitReader reader;
+  unsigned error = LodePNGBitReader_init(&reader, in, insize);
 
-  (void)settings;
+  if(error) return error;
 
-  while(!BFINAL)
-  {
+  while(!BFINAL) {
     unsigned BTYPE;
-    if(bp + 2 >= insize * 8) return 52; /*error, bit pointer will jump past memory*/
-    BFINAL = readBitFromStream(&bp, in);
-    BTYPE = 1u * readBitFromStream(&bp, in);
-    BTYPE += 2u * readBitFromStream(&bp, in);
+    if(!ensureBits9(&reader, 3)) return 52; /*error, bit pointer will jump past memory*/
+    BFINAL = readBits(&reader, 1);
+    BTYPE = readBits(&reader, 2);
 
     if(BTYPE == 3) return 20; /*error: invalid BTYPE*/
-    else if(BTYPE == 0) error = inflateNoCompression(out, in, &bp, &pos, insize); /*no compression*/
-    else error = inflateHuffmanBlock(out, in, &bp, &pos, insize, BTYPE); /*compression, BTYPE 01 or 10*/
+    else if(BTYPE == 0) error = inflateNoCompression(out, &pos, &reader, settings); /*no compression*/
+    else error = inflateHuffmanBlock(out, &pos, &reader, BTYPE); /*compression, BTYPE 01 or 10*/
 
     if(error) return error;
   }
@@ -1265,8 +1413,7 @@ static unsigned lodepng_inflatev(ucvector* out,
 
 unsigned lodepng_inflate(unsigned char** out, size_t* outsize,
                          const unsigned char* in, size_t insize,
-                         const LodePNGDecompressSettings* settings)
-{
+                         const LodePNGDecompressSettings* settings) {
   unsigned error;
   ucvector v;
   ucvector_init_buffer(&v, *out, *outsize);
@@ -1278,14 +1425,10 @@ unsigned lodepng_inflate(unsigned char** out, size_t* outsize,
 
 static unsigned inflate(unsigned char** out, size_t* outsize,
                         const unsigned char* in, size_t insize,
-                        const LodePNGDecompressSettings* settings)
-{
-  if(settings->custom_inflate)
-  {
+                        const LodePNGDecompressSettings* settings) {
+  if(settings->custom_inflate) {
     return settings->custom_inflate(out, outsize, in, insize, settings);
-  }
-  else
-  {
+  } else {
     return lodepng_inflate(out, outsize, in, insize, settings);
   }
 }
@@ -1300,16 +1443,9 @@ static unsigned inflate(unsigned char** out, size_t* outsize,
 
 static const size_t MAX_SUPPORTED_DEFLATE_LENGTH = 258;
 
-/*bitlen is the size in bits of the code*/
-static void addHuffmanSymbol(size_t* bp, ucvector* compressed, unsigned code, unsigned bitlen)
-{
-  addBitsToStreamReversed(bp, compressed, code, bitlen);
-}
-
 /*search the index in the array, that has the largest value smaller than or equal to the given value,
 given array must be sorted (if no value is smaller, it returns the size of the given array)*/
-static size_t searchCodeIndex(const unsigned* array, size_t array_size, size_t value)
-{
+static size_t searchCodeIndex(const unsigned* array, size_t array_size, size_t value) {
   /*binary search (only small gain over linear). TODO: use CPU log2 instruction for getting symbols instead*/
   size_t left = 1;
   size_t right = array_size - 1;
@@ -1323,8 +1459,7 @@ static size_t searchCodeIndex(const unsigned* array, size_t array_size, size_t v
   return left;
 }
 
-static void addLengthDistance(uivector* values, size_t length, size_t distance)
-{
+static void addLengthDistance(uivector* values, size_t length, size_t distance) {
   /*values in encoded vector are those used by deflate:
   0-255: literal bytes
   256: end
@@ -1347,8 +1482,7 @@ bytes as input because 3 is the minimum match length for deflate*/
 static const unsigned HASH_NUM_VALUES = 65536;
 static const unsigned HASH_BIT_MASK = 65535; /*HASH_NUM_VALUES - 1, but C90 does not like that as initializer*/
 
-typedef struct Hash
-{
+typedef struct Hash {
   int* head; /*hash value to head circular pos - can be outdated if went around window*/
   /*circular pos to prev circular pos*/
   unsigned short* chain;
@@ -1361,8 +1495,7 @@ typedef struct Hash
   unsigned short* zeros; /*length of zeros streak, used as a second hash chain*/
 } Hash;
 
-static unsigned hash_init(Hash* hash, unsigned windowsize)
-{
+static unsigned hash_init(Hash* hash, unsigned windowsize) {
   unsigned i;
   hash->head = (int*)lodepng_malloc(sizeof(int) * HASH_NUM_VALUES);
   hash->val = (int*)lodepng_malloc(sizeof(int) * windowsize);
@@ -1372,8 +1505,7 @@ static unsigned hash_init(Hash* hash, unsigned windowsize)
   hash->headz = (int*)lodepng_malloc(sizeof(int) * (MAX_SUPPORTED_DEFLATE_LENGTH + 1));
   hash->chainz = (unsigned short*)lodepng_malloc(sizeof(unsigned short) * windowsize);
 
-  if(!hash->head || !hash->chain || !hash->val  || !hash->headz|| !hash->chainz || !hash->zeros)
-  {
+  if(!hash->head || !hash->chain || !hash->val  || !hash->headz|| !hash->chainz || !hash->zeros) {
     return 83; /*alloc fail*/
   }
 
@@ -1388,8 +1520,7 @@ static unsigned hash_init(Hash* hash, unsigned windowsize)
   return 0;
 }
 
-static void hash_cleanup(Hash* hash)
-{
+static void hash_cleanup(Hash* hash) {
   lodepng_free(hash->head);
   lodepng_free(hash->val);
   lodepng_free(hash->chain);
@@ -1401,11 +1532,9 @@ static void hash_cleanup(Hash* hash)
 
 
 
-static unsigned getHash(const unsigned char* data, size_t size, size_t pos)
-{
+static unsigned getHash(const unsigned char* data, size_t size, size_t pos) {
   unsigned result = 0;
-  if(pos + 2 < size)
-  {
+  if(pos + 2 < size) {
     /*A simple shift and xor hash is used. Since the data of PNGs is dominated
     by zeroes due to the filters, a better hash does not have a significant
     effect on speed in traversing the chain, and causes more time spend on
@@ -1422,8 +1551,7 @@ static unsigned getHash(const unsigned char* data, size_t size, size_t pos)
   return result & HASH_BIT_MASK;
 }
 
-static unsigned countZeros(const unsigned char* data, size_t size, size_t pos)
-{
+static unsigned countZeros(const unsigned char* data, size_t size, size_t pos) {
   const unsigned char* start = data + pos;
   const unsigned char* end = start + MAX_SUPPORTED_DEFLATE_LENGTH;
   if(end > data + size) end = data + size;
@@ -1434,15 +1562,14 @@ static unsigned countZeros(const unsigned char* data, size_t size, size_t pos)
 }
 
 /*wpos = pos & (windowsize - 1)*/
-static void updateHashChain(Hash* hash, size_t wpos, unsigned hashval, unsigned short numzeros)
-{
+static void updateHashChain(Hash* hash, size_t wpos, unsigned hashval, unsigned short numzeros) {
   hash->val[wpos] = (int)hashval;
   if(hash->head[hashval] != -1) hash->chain[wpos] = hash->head[hashval];
-  hash->head[hashval] = wpos;
+  hash->head[hashval] = (int)wpos;
 
   hash->zeros[wpos] = numzeros;
   if(hash->headz[numzeros] != -1) hash->chainz[wpos] = hash->headz[numzeros];
-  hash->headz[numzeros] = wpos;
+  hash->headz[numzeros] = (int)wpos;
 }
 
 /*
@@ -1456,12 +1583,11 @@ this hash technique is one out of several ways to speed this up.
 */
 static unsigned encodeLZ77(uivector* out, Hash* hash,
                            const unsigned char* in, size_t inpos, size_t insize, unsigned windowsize,
-                           unsigned minmatch, unsigned nicematch, unsigned lazymatching)
-{
+                           unsigned minmatch, unsigned nicematch, unsigned lazymatching) {
   size_t pos;
   unsigned i, error = 0;
   /*for large window lengths, assume the user wants no compression loss. Otherwise, max hash chain length speedup.*/
-  unsigned maxchainlength = windowsize >= 8192 ? windowsize : windowsize / 8;
+  unsigned maxchainlength = windowsize >= 8192 ? windowsize : windowsize / 8u;
   unsigned maxlazymatch = windowsize >= 8192 ? MAX_SUPPORTED_DEFLATE_LENGTH : 64;
 
   unsigned usezeros = 1; /*not sure if setting it to false for windowsize < 8192 is better or worse*/
@@ -1482,20 +1608,16 @@ static unsigned encodeLZ77(uivector* out, Hash* hash,
 
   if(nicematch > MAX_SUPPORTED_DEFLATE_LENGTH) nicematch = MAX_SUPPORTED_DEFLATE_LENGTH;
 
-  for(pos = inpos; pos < insize; ++pos)
-  {
+  for(pos = inpos; pos < insize; ++pos) {
     size_t wpos = pos & (windowsize - 1); /*position for in 'circular' hash buffers*/
     unsigned chainlength = 0;
 
     hashval = getHash(in, insize, pos);
 
-    if(usezeros && hashval == 0)
-    {
+    if(usezeros && hashval == 0) {
       if(numzeros == 0) numzeros = countZeros(in, insize, pos);
       else if(pos + numzeros > insize || in[pos + numzeros - 1] != 0) --numzeros;
-    }
-    else
-    {
+    } else {
       numzeros = 0;
     }
 
@@ -1511,37 +1633,32 @@ static unsigned encodeLZ77(uivector* out, Hash* hash,
 
     /*search for the longest string*/
     prev_offset = 0;
-    for(;;)
-    {
+    for(;;) {
       if(chainlength++ >= maxchainlength) break;
-      current_offset = hashpos <= wpos ? wpos - hashpos : wpos - hashpos + windowsize;
+      current_offset = (unsigned)(hashpos <= wpos ? wpos - hashpos : wpos - hashpos + windowsize);
 
       if(current_offset < prev_offset) break; /*stop when went completely around the circular buffer*/
       prev_offset = current_offset;
-      if(current_offset > 0)
-      {
+      if(current_offset > 0) {
         /*test the next characters*/
         foreptr = &in[pos];
         backptr = &in[pos - current_offset];
 
         /*common case in PNGs is lots of zeros. Quickly skip over them as a speedup*/
-        if(numzeros >= 3)
-        {
+        if(numzeros >= 3) {
           unsigned skip = hash->zeros[hashpos];
           if(skip > numzeros) skip = numzeros;
           backptr += skip;
           foreptr += skip;
         }
 
-        while(foreptr != lastptr && *backptr == *foreptr) /*maximum supported length by deflate is max length*/
-        {
+        while(foreptr != lastptr && *backptr == *foreptr) /*maximum supported length by deflate is max length*/ {
           ++backptr;
           ++foreptr;
         }
         current_length = (unsigned)(foreptr - &in[pos]);
 
-        if(current_length > length)
-        {
+        if(current_length > length) {
           length = current_length; /*the longest length*/
           offset = current_offset; /*the offset that is related to this longest length*/
           /*jump out once a length of max length is found (speed gain). This also jumps
@@ -1552,39 +1669,30 @@ static unsigned encodeLZ77(uivector* out, Hash* hash,
 
       if(hashpos == hash->chain[hashpos]) break;
 
-      if(numzeros >= 3 && length > numzeros)
-      {
+      if(numzeros >= 3 && length > numzeros) {
         hashpos = hash->chainz[hashpos];
         if(hash->zeros[hashpos] != numzeros) break;
-      }
-      else
-      {
+      } else {
         hashpos = hash->chain[hashpos];
         /*outdated hash value, happens if particular value was not encountered in whole last window*/
         if(hash->val[hashpos] != (int)hashval) break;
       }
     }
 
-    if(lazymatching)
-    {
-      if(!lazy && length >= 3 && length <= maxlazymatch && length < MAX_SUPPORTED_DEFLATE_LENGTH)
-      {
+    if(lazymatching) {
+      if(!lazy && length >= 3 && length <= maxlazymatch && length < MAX_SUPPORTED_DEFLATE_LENGTH) {
         lazy = 1;
         lazylength = length;
         lazyoffset = offset;
         continue; /*try the next byte*/
       }
-      if(lazy)
-      {
+      if(lazy) {
         lazy = 0;
         if(pos == 0) ERROR_BREAK(81);
-        if(length > lazylength + 1)
-        {
+        if(length > lazylength + 1) {
           /*push the previous character as literal*/
           if(!uivector_push_back(out, in[pos - 1])) ERROR_BREAK(83 /*alloc fail*/);
-        }
-        else
-        {
+        } else {
           length = lazylength;
           offset = lazyoffset;
           hash->head[hashval] = -1; /*the same hashchain update will be done, this ensures no wrong alteration*/
@@ -1596,31 +1704,22 @@ static unsigned encodeLZ77(uivector* out, Hash* hash,
     if(length >= 3 && offset > windowsize) ERROR_BREAK(86 /*too big (or overflown negative) offset*/);
 
     /*encode it as length/distance pair or literal value*/
-    if(length < 3) /*only lengths of 3 or higher are supported as length/distance pair*/
-    {
+    if(length < 3) /*only lengths of 3 or higher are supported as length/distance pair*/ {
       if(!uivector_push_back(out, in[pos])) ERROR_BREAK(83 /*alloc fail*/);
-    }
-    else if(length < minmatch || (length == 3 && offset > 4096))
-    {
+    } else if(length < minmatch || (length == 3 && offset > 4096)) {
       /*compensate for the fact that longer offsets have more extra bits, a
       length of only 3 may be not worth it then*/
       if(!uivector_push_back(out, in[pos])) ERROR_BREAK(83 /*alloc fail*/);
-    }
-    else
-    {
+    } else {
       addLengthDistance(out, length, offset);
-      for(i = 1; i < length; ++i)
-      {
+      for(i = 1; i < length; ++i) {
         ++pos;
         wpos = pos & (windowsize - 1);
         hashval = getHash(in, insize, pos);
-        if(usezeros && hashval == 0)
-        {
+        if(usezeros && hashval == 0) {
           if(numzeros == 0) numzeros = countZeros(in, insize, pos);
           else if(pos + numzeros > insize || in[pos + numzeros - 1] != 0) --numzeros;
-        }
-        else
-        {
+        } else {
           numzeros = 0;
         }
         updateHashChain(hash, wpos, hashval, numzeros);
@@ -1633,15 +1732,13 @@ static unsigned encodeLZ77(uivector* out, Hash* hash,
 
 /* /////////////////////////////////////////////////////////////////////////// */
 
-static unsigned deflateNoCompression(ucvector* out, const unsigned char* data, size_t datasize)
-{
+static unsigned deflateNoCompression(ucvector* out, const unsigned char* data, size_t datasize) {
   /*non compressed deflate block data: 1 bit BFINAL,2 bits BTYPE,(5 bits): it jumps to start of next byte,
   2 bytes LEN, 2 bytes NLEN, LEN bytes literal DATA*/
 
-  size_t i, j, numdeflateblocks = (datasize + 65534) / 65535;
+  size_t i, j, numdeflateblocks = (datasize + 65534u) / 65535u;
   unsigned datapos = 0;
-  for(i = 0; i != numdeflateblocks; ++i)
-  {
+  for(i = 0; i != numdeflateblocks; ++i) {
     unsigned BFINAL, BTYPE, LEN, NLEN;
     unsigned char firstbyte;
 
@@ -1652,17 +1749,16 @@ static unsigned deflateNoCompression(ucvector* out, const unsigned char* data, s
     ucvector_push_back(out, firstbyte);
 
     LEN = 65535;
-    if(datasize - datapos < 65535) LEN = (unsigned)datasize - datapos;
+    if(datasize - datapos < 65535u) LEN = (unsigned)datasize - datapos;
     NLEN = 65535 - LEN;
 
     ucvector_push_back(out, (unsigned char)(LEN & 255));
-    ucvector_push_back(out, (unsigned char)(LEN >> 8));
+    ucvector_push_back(out, (unsigned char)(LEN >> 8u));
     ucvector_push_back(out, (unsigned char)(NLEN & 255));
-    ucvector_push_back(out, (unsigned char)(NLEN >> 8));
+    ucvector_push_back(out, (unsigned char)(NLEN >> 8u));
 
     /*Decompressed data*/
-    for(j = 0; j < 65535 && datapos < datasize; ++j)
-    {
+    for(j = 0; j < 65535 && datapos < datasize; ++j) {
       ucvector_push_back(out, data[datapos++]);
     }
   }
@@ -1675,16 +1771,13 @@ write the lz77-encoded data, which has lit, len and dist codes, to compressed st
 tree_ll: the tree for lit and len codes.
 tree_d: the tree for distance codes.
 */
-static void writeLZ77data(size_t* bp, ucvector* out, const uivector* lz77_encoded,
-                          const HuffmanTree* tree_ll, const HuffmanTree* tree_d)
-{
+static void writeLZ77data(LodePNGBitWriter* writer, const uivector* lz77_encoded,
+                          const HuffmanTree* tree_ll, const HuffmanTree* tree_d) {
   size_t i = 0;
-  for(i = 0; i != lz77_encoded->size; ++i)
-  {
+  for(i = 0; i != lz77_encoded->size; ++i) {
     unsigned val = lz77_encoded->data[i];
-    addHuffmanSymbol(bp, out, HuffmanTree_getCode(tree_ll, val), HuffmanTree_getLength(tree_ll, val));
-    if(val > 256) /*for a length code, 3 more things have to be added*/
-    {
+    writeBitsReversed(writer, HuffmanTree_getCode(tree_ll, val), HuffmanTree_getLength(tree_ll, val));
+    if(val > 256) /*for a length code, 3 more things have to be added*/ {
       unsigned length_index = val - FIRST_LENGTH_CODE_INDEX;
       unsigned n_length_extra_bits = LENGTHEXTRA[length_index];
       unsigned length_extra_bits = lz77_encoded->data[++i];
@@ -1695,19 +1788,18 @@ static void writeLZ77data(size_t* bp, ucvector* out, const uivector* lz77_encode
       unsigned n_distance_extra_bits = DISTANCEEXTRA[distance_index];
       unsigned distance_extra_bits = lz77_encoded->data[++i];
 
-      addBitsToStream(bp, out, length_extra_bits, n_length_extra_bits);
-      addHuffmanSymbol(bp, out, HuffmanTree_getCode(tree_d, distance_code),
+      writeBits(writer, length_extra_bits, n_length_extra_bits);
+      writeBitsReversed(writer, HuffmanTree_getCode(tree_d, distance_code),
                        HuffmanTree_getLength(tree_d, distance_code));
-      addBitsToStream(bp, out, distance_extra_bits, n_distance_extra_bits);
+      writeBits(writer, distance_extra_bits, n_distance_extra_bits);
     }
   }
 }
 
 /*Deflate for a block of type "dynamic", that is, with freely, optimally, created huffman trees*/
-static unsigned deflateDynamic(ucvector* out, size_t* bp, Hash* hash,
+static unsigned deflateDynamic(LodePNGBitWriter* writer, Hash* hash,
                                const unsigned char* data, size_t datapos, size_t dataend,
-                               const LodePNGCompressSettings* settings, unsigned final)
-{
+                               const LodePNGCompressSettings* settings, unsigned final) {
   unsigned error = 0;
 
   /*
@@ -1717,7 +1809,7 @@ static unsigned deflateDynamic(ucvector* out, size_t* bp, Hash* hash,
   another huffman tree is used for the dist values ("d"). These two trees are
   stored using their code lengths, and to compress even more these code lengths
   are also run-length encoded and huffman compressed. This gives a huffman tree
-  of code lengths "cl". The code lenghts used to describe this third tree are
+  of code lengths "cl". The code lengths used to describe this third tree are
   the code length code lengths ("clcl").
   */
 
@@ -1729,8 +1821,8 @@ static unsigned deflateDynamic(ucvector* out, size_t* bp, Hash* hash,
   uivector frequencies_ll; /*frequency of lit,len codes*/
   uivector frequencies_d; /*frequency of dist codes*/
   uivector frequencies_cl; /*frequency of code length codes*/
-  uivector bitlen_lld; /*lit,len,dist code lenghts (int bits), literally (without repeat codes).*/
-  uivector bitlen_lld_e; /*bitlen_lld encoded with repeat codes (this is a rudemtary run length compression)*/
+  uivector bitlen_lld; /*lit,len,dist code lengths (int bits), literally (without repeat codes).*/
+  uivector bitlen_lld_e; /*bitlen_lld encoded with repeat codes (this is a rudimentary run length compression)*/
   /*bitlen_cl is the code length code lengths ("clcl"). The bit lengths of codes to represent tree_cl
   (these are written as is in the file, it would be crazy to compress these using yet another huffman
   tree that needs to be represented by yet another set of code lengths)*/
@@ -1738,7 +1830,7 @@ static unsigned deflateDynamic(ucvector* out, size_t* bp, Hash* hash,
   size_t datasize = dataend - datapos;
 
   /*
-  Due to the huffman compression of huffman tree representations ("two levels"), there are some anologies:
+  Due to the huffman compression of huffman tree representations ("two levels"), there are some analogies:
   bitlen_lld is to tree_cl what data is to tree_ll and tree_d.
   bitlen_lld_e is to bitlen_lld what lz77_encoded is to data.
   bitlen_cl is to bitlen_lld_e what bitlen_lld is to lz77_encoded.
@@ -1761,16 +1853,12 @@ static unsigned deflateDynamic(ucvector* out, size_t* bp, Hash* hash,
 
   /*This while loop never loops due to a break at the end, it is here to
   allow breaking out of it to the cleanup phase on error conditions.*/
-  while(!error)
-  {
-    if(settings->use_lz77)
-    {
+  while(!error) {
+    if(settings->use_lz77) {
       error = encodeLZ77(&lz77_encoded, hash, data, datapos, dataend, settings->windowsize,
                          settings->minmatch, settings->nicematch, settings->lazymatching);
       if(error) break;
-    }
-    else
-    {
+    } else {
       if(!uivector_resize(&lz77_encoded, datasize)) ERROR_BREAK(83 /*alloc fail*/);
       for(i = datapos; i < dataend; ++i) lz77_encoded.data[i - datapos] = data[i]; /*no LZ77, but still will be Huffman compressed*/
     }
@@ -1779,12 +1867,10 @@ static unsigned deflateDynamic(ucvector* out, size_t* bp, Hash* hash,
     if(!uivector_resizev(&frequencies_d, 30, 0)) ERROR_BREAK(83 /*alloc fail*/);
 
     /*Count the frequencies of lit, len and dist codes*/
-    for(i = 0; i != lz77_encoded.size; ++i)
-    {
+    for(i = 0; i != lz77_encoded.size; ++i) {
       unsigned symbol = lz77_encoded.data[i];
       ++frequencies_ll.data[symbol];
-      if(symbol > 256)
-      {
+      if(symbol > 256) {
         unsigned dist = lz77_encoded.data[i + 2];
         ++frequencies_d.data[dist];
         i += 3;
@@ -1807,47 +1893,36 @@ static unsigned deflateDynamic(ucvector* out, size_t* bp, Hash* hash,
 
     /*run-length compress bitlen_ldd into bitlen_lld_e by using repeat codes 16 (copy length 3-6 times),
     17 (3-10 zeroes), 18 (11-138 zeroes)*/
-    for(i = 0; i != (unsigned)bitlen_lld.size; ++i)
-    {
-      unsigned j = 0; /*amount of repititions*/
+    for(i = 0; i != (unsigned)bitlen_lld.size; ++i) {
+      unsigned j = 0; /*amount of repetitions*/
       while(i + j + 1 < (unsigned)bitlen_lld.size && bitlen_lld.data[i + j + 1] == bitlen_lld.data[i]) ++j;
 
-      if(bitlen_lld.data[i] == 0 && j >= 2) /*repeat code for zeroes*/
-      {
+      if(bitlen_lld.data[i] == 0 && j >= 2) /*repeat code for zeroes*/ {
         ++j; /*include the first zero*/
-        if(j <= 10) /*repeat code 17 supports max 10 zeroes*/
-        {
+        if(j <= 10) /*repeat code 17 supports max 10 zeroes*/ {
           uivector_push_back(&bitlen_lld_e, 17);
           uivector_push_back(&bitlen_lld_e, j - 3);
-        }
-        else /*repeat code 18 supports max 138 zeroes*/
-        {
+        } else /*repeat code 18 supports max 138 zeroes*/ {
           if(j > 138) j = 138;
           uivector_push_back(&bitlen_lld_e, 18);
           uivector_push_back(&bitlen_lld_e, j - 11);
         }
         i += (j - 1);
-      }
-      else if(j >= 3) /*repeat code for value other than zero*/
-      {
+      } else if(j >= 3) /*repeat code for value other than zero*/ {
         size_t k;
-        unsigned num = j / 6, rest = j % 6;
+        unsigned num = j / 6u, rest = j % 6u;
         uivector_push_back(&bitlen_lld_e, bitlen_lld.data[i]);
-        for(k = 0; k < num; ++k)
-        {
+        for(k = 0; k < num; ++k) {
           uivector_push_back(&bitlen_lld_e, 16);
           uivector_push_back(&bitlen_lld_e, 6 - 3);
         }
-        if(rest >= 3)
-        {
+        if(rest >= 3) {
           uivector_push_back(&bitlen_lld_e, 16);
           uivector_push_back(&bitlen_lld_e, rest - 3);
         }
         else j -= rest;
         i += j;
-      }
-      else /*too short to benefit from repeat code*/
-      {
+      } else /*too short to benefit from repeat code*/ {
         uivector_push_back(&bitlen_lld_e, bitlen_lld.data[i]);
       }
     }
@@ -1855,8 +1930,7 @@ static unsigned deflateDynamic(ucvector* out, size_t* bp, Hash* hash,
     /*generate tree_cl, the huffmantree of huffmantrees*/
 
     if(!uivector_resizev(&frequencies_cl, NUM_CODE_LENGTH_CODES, 0)) ERROR_BREAK(83 /*alloc fail*/);
-    for(i = 0; i != bitlen_lld_e.size; ++i)
-    {
+    for(i = 0; i != bitlen_lld_e.size; ++i) {
       ++frequencies_cl.data[bitlen_lld_e.data[i]];
       /*after a repeat code come the bits that specify the number of repetitions,
       those don't need to be in the frequencies_cl calculation*/
@@ -1868,13 +1942,11 @@ static unsigned deflateDynamic(ucvector* out, size_t* bp, Hash* hash,
     if(error) break;
 
     if(!uivector_resize(&bitlen_cl, tree_cl.numcodes)) ERROR_BREAK(83 /*alloc fail*/);
-    for(i = 0; i != tree_cl.numcodes; ++i)
-    {
-      /*lenghts of code length tree is in the order as specified by deflate*/
+    for(i = 0; i != tree_cl.numcodes; ++i) {
+      /*lengths of code length tree is in the order as specified by deflate*/
       bitlen_cl.data[i] = HuffmanTree_getLength(&tree_cl, CLCL_ORDER[i]);
     }
-    while(bitlen_cl.data[bitlen_cl.size - 1] == 0 && bitlen_cl.size > 4)
-    {
+    while(bitlen_cl.data[bitlen_cl.size - 1] == 0 && bitlen_cl.size > 4) {
       /*remove zeros at the end, but minimum size must be 4*/
       if(!uivector_resize(&bitlen_cl, bitlen_cl.size - 1)) ERROR_BREAK(83 /*alloc fail*/);
     }
@@ -1886,7 +1958,7 @@ static unsigned deflateDynamic(ucvector* out, size_t* bp, Hash* hash,
     After the BFINAL and BTYPE, the dynamic block consists out of the following:
     - 5 bits HLIT, 5 bits HDIST, 4 bits HCLEN
     - (HCLEN+4)*3 bits code lengths of code length alphabet
-    - HLIT + 257 code lenghts of lit/length alphabet (encoded using the code length
+    - HLIT + 257 code lengths of lit/length alphabet (encoded using the code length
       alphabet, + possible repetition codes 16, 17, 18)
     - HDIST + 1 code lengths of distance alphabet (encoded using the code length
       alphabet, + possible repetition codes 16, 17, 18)
@@ -1895,9 +1967,9 @@ static unsigned deflateDynamic(ucvector* out, size_t* bp, Hash* hash,
     */
 
     /*Write block type*/
-    addBitToStream(bp, out, BFINAL);
-    addBitToStream(bp, out, 0); /*first bit of BTYPE "dynamic"*/
-    addBitToStream(bp, out, 1); /*second bit of BTYPE "dynamic"*/
+    writeBits(writer, BFINAL, 1);
+    writeBits(writer, 0, 1); /*first bit of BTYPE "dynamic"*/
+    writeBits(writer, 1, 1); /*second bit of BTYPE "dynamic"*/
 
     /*write the HLIT, HDIST and HCLEN values*/
     HLIT = (unsigned)(numcodes_ll - 257);
@@ -1905,31 +1977,30 @@ static unsigned deflateDynamic(ucvector* out, size_t* bp, Hash* hash,
     HCLEN = (unsigned)bitlen_cl.size - 4;
     /*trim zeroes for HCLEN. HLIT and HDIST were already trimmed at tree creation*/
     while(!bitlen_cl.data[HCLEN + 4 - 1] && HCLEN > 0) --HCLEN;
-    addBitsToStream(bp, out, HLIT, 5);
-    addBitsToStream(bp, out, HDIST, 5);
-    addBitsToStream(bp, out, HCLEN, 4);
-
-    /*write the code lenghts of the code length alphabet*/
-    for(i = 0; i != HCLEN + 4; ++i) addBitsToStream(bp, out, bitlen_cl.data[i], 3);
-
-    /*write the lenghts of the lit/len AND the dist alphabet*/
-    for(i = 0; i != bitlen_lld_e.size; ++i)
-    {
-      addHuffmanSymbol(bp, out, HuffmanTree_getCode(&tree_cl, bitlen_lld_e.data[i]),
-                       HuffmanTree_getLength(&tree_cl, bitlen_lld_e.data[i]));
+    writeBits(writer, HLIT, 5);
+    writeBits(writer, HDIST, 5);
+    writeBits(writer, HCLEN, 4);
+
+    /*write the code lengths of the code length alphabet*/
+    for(i = 0; i != HCLEN + 4; ++i) writeBits(writer, bitlen_cl.data[i], 3);
+
+    /*write the lengths of the lit/len AND the dist alphabet*/
+    for(i = 0; i != bitlen_lld_e.size; ++i) {
+      writeBitsReversed(writer, HuffmanTree_getCode(&tree_cl, bitlen_lld_e.data[i]),
+                        HuffmanTree_getLength(&tree_cl, bitlen_lld_e.data[i]));
       /*extra bits of repeat codes*/
-      if(bitlen_lld_e.data[i] == 16) addBitsToStream(bp, out, bitlen_lld_e.data[++i], 2);
-      else if(bitlen_lld_e.data[i] == 17) addBitsToStream(bp, out, bitlen_lld_e.data[++i], 3);
-      else if(bitlen_lld_e.data[i] == 18) addBitsToStream(bp, out, bitlen_lld_e.data[++i], 7);
+      if(bitlen_lld_e.data[i] == 16) writeBits(writer, bitlen_lld_e.data[++i], 2);
+      else if(bitlen_lld_e.data[i] == 17) writeBits(writer, bitlen_lld_e.data[++i], 3);
+      else if(bitlen_lld_e.data[i] == 18) writeBits(writer, bitlen_lld_e.data[++i], 7);
     }
 
     /*write the compressed data symbols*/
-    writeLZ77data(bp, out, &lz77_encoded, &tree_ll, &tree_d);
+    writeLZ77data(writer, &lz77_encoded, &tree_ll, &tree_d);
     /*error: the length of the end code 256 must be larger than 0*/
     if(HuffmanTree_getLength(&tree_ll, 256) == 0) ERROR_BREAK(64);
 
     /*write the end code*/
-    addHuffmanSymbol(bp, out, HuffmanTree_getCode(&tree_ll, 256), HuffmanTree_getLength(&tree_ll, 256));
+    writeBitsReversed(writer, HuffmanTree_getCode(&tree_ll, 256), HuffmanTree_getLength(&tree_ll, 256));
 
     break; /*end of error-while*/
   }
@@ -1949,11 +2020,10 @@ static unsigned deflateDynamic(ucvector* out, size_t* bp, Hash* hash,
   return error;
 }
 
-static unsigned deflateFixed(ucvector* out, size_t* bp, Hash* hash,
+static unsigned deflateFixed(LodePNGBitWriter* writer, Hash* hash,
                              const unsigned char* data,
                              size_t datapos, size_t dataend,
-                             const LodePNGCompressSettings* settings, unsigned final)
-{
+                             const LodePNGCompressSettings* settings, unsigned final) {
   HuffmanTree tree_ll; /*tree for literal values and length codes*/
   HuffmanTree tree_d; /*tree for distance codes*/
 
@@ -1967,28 +2037,24 @@ static unsigned deflateFixed(ucvector* out, size_t* bp, Hash* hash,
   generateFixedLitLenTree(&tree_ll);
   generateFixedDistanceTree(&tree_d);
 
-  addBitToStream(bp, out, BFINAL);
-  addBitToStream(bp, out, 1); /*first bit of BTYPE*/
-  addBitToStream(bp, out, 0); /*second bit of BTYPE*/
+  writeBits(writer, BFINAL, 1);
+  writeBits(writer, 1, 1); /*first bit of BTYPE*/
+  writeBits(writer, 0, 1); /*second bit of BTYPE*/
 
-  if(settings->use_lz77) /*LZ77 encoded*/
-  {
+  if(settings->use_lz77) /*LZ77 encoded*/ {
     uivector lz77_encoded;
     uivector_init(&lz77_encoded);
     error = encodeLZ77(&lz77_encoded, hash, data, datapos, dataend, settings->windowsize,
                        settings->minmatch, settings->nicematch, settings->lazymatching);
-    if(!error) writeLZ77data(bp, out, &lz77_encoded, &tree_ll, &tree_d);
+    if(!error) writeLZ77data(writer, &lz77_encoded, &tree_ll, &tree_d);
     uivector_cleanup(&lz77_encoded);
-  }
-  else /*no LZ77, but still will be Huffman compressed*/
-  {
-    for(i = datapos; i < dataend; ++i)
-    {
-      addHuffmanSymbol(bp, out, HuffmanTree_getCode(&tree_ll, data[i]), HuffmanTree_getLength(&tree_ll, data[i]));
+  } else /*no LZ77, but still will be Huffman compressed*/ {
+    for(i = datapos; i < dataend; ++i) {
+      writeBitsReversed(writer, HuffmanTree_getCode(&tree_ll, data[i]), HuffmanTree_getLength(&tree_ll, data[i]));
     }
   }
   /*add END code*/
-  if(!error) addHuffmanSymbol(bp, out, HuffmanTree_getCode(&tree_ll, 256), HuffmanTree_getLength(&tree_ll, 256));
+  if(!error) writeBitsReversed(writer, HuffmanTree_getCode(&tree_ll, 256), HuffmanTree_getLength(&tree_ll, 256));
 
   /*cleanup*/
   HuffmanTree_cleanup(&tree_ll);
@@ -1998,20 +2064,20 @@ static unsigned deflateFixed(ucvector* out, size_t* bp, Hash* hash,
 }
 
 static unsigned lodepng_deflatev(ucvector* out, const unsigned char* in, size_t insize,
-                                 const LodePNGCompressSettings* settings)
-{
+                                 const LodePNGCompressSettings* settings) {
   unsigned error = 0;
   size_t i, blocksize, numdeflateblocks;
-  size_t bp = 0; /*the bit pointer*/
   Hash hash;
+  LodePNGBitWriter writer;
+
+  LodePNGBitWriter_init(&writer, out);
 
   if(settings->btype > 2) return 61;
   else if(settings->btype == 0) return deflateNoCompression(out, in, insize);
   else if(settings->btype == 1) blocksize = insize;
-  else /*if(settings->btype == 2)*/
-  {
+  else /*if(settings->btype == 2)*/ {
     /*on PNGs, deflate blocks of 65-262k seem to give most dense encoding*/
-    blocksize = insize / 8 + 8;
+    blocksize = insize / 8u + 8;
     if(blocksize < 65536) blocksize = 65536;
     if(blocksize > 262144) blocksize = 262144;
   }
@@ -2022,15 +2088,14 @@ static unsigned lodepng_deflatev(ucvector* out, const unsigned char* in, size_t
   error = hash_init(&hash, settings->windowsize);
   if(error) return error;
 
-  for(i = 0; i != numdeflateblocks && !error; ++i)
-  {
+  for(i = 0; i != numdeflateblocks && !error; ++i) {
     unsigned final = (i == numdeflateblocks - 1);
     size_t start = i * blocksize;
     size_t end = start + blocksize;
     if(end > insize) end = insize;
 
-    if(settings->btype == 1) error = deflateFixed(out, &bp, &hash, in, start, end, settings, final);
-    else if(settings->btype == 2) error = deflateDynamic(out, &bp, &hash, in, start, end, settings, final);
+    if(settings->btype == 1) error = deflateFixed(&writer, &hash, in, start, end, settings, final);
+    else if(settings->btype == 2) error = deflateDynamic(&writer, &hash, in, start, end, settings, final);
   }
 
   hash_cleanup(&hash);
@@ -2040,8 +2105,7 @@ static unsigned lodepng_deflatev(ucvector* out, const unsigned char* in, size_t
 
 unsigned lodepng_deflate(unsigned char** out, size_t* outsize,
                          const unsigned char* in, size_t insize,
-                         const LodePNGCompressSettings* settings)
-{
+                         const LodePNGCompressSettings* settings) {
   unsigned error;
   ucvector v;
   ucvector_init_buffer(&v, *out, *outsize);
@@ -2053,14 +2117,10 @@ unsigned lodepng_deflate(unsigned char** out, size_t* outsize,
 
 static unsigned deflate(unsigned char** out, size_t* outsize,
                         const unsigned char* in, size_t insize,
-                        const LodePNGCompressSettings* settings)
-{
-  if(settings->custom_deflate)
-  {
+                        const LodePNGCompressSettings* settings) {
+  if(settings->custom_deflate) {
     return settings->custom_deflate(out, outsize, in, insize, settings);
-  }
-  else
-  {
+  } else {
     return lodepng_deflate(out, outsize, in, insize, settings);
   }
 }
@@ -2068,36 +2128,32 @@ static unsigned deflate(unsigned char** out, size_t* outsize,
 #endif /*LODEPNG_COMPILE_DECODER*/
 
 /* ////////////////////////////////////////////////////////////////////////// */
-/* / Adler32                                                                  */
+/* / Adler32                                                                / */
 /* ////////////////////////////////////////////////////////////////////////// */
 
-static unsigned update_adler32(unsigned adler, const unsigned char* data, unsigned len)
-{
-   unsigned s1 = adler & 0xffff;
-   unsigned s2 = (adler >> 16) & 0xffff;
+static unsigned update_adler32(unsigned adler, const unsigned char* data, unsigned len) {
+  unsigned s1 = adler & 0xffffu;
+  unsigned s2 = (adler >> 16u) & 0xffffu;
 
-  while(len > 0)
-  {
-    /*at least 5550 sums can be done before the sums overflow, saving a lot of module divisions*/
-    unsigned amount = len > 5550 ? 5550 : len;
+  while(len != 0u) {
+    unsigned i;
+    /*at least 5552 sums can be done before the sums overflow, saving a lot of module divisions*/
+    unsigned amount = len > 5552u ? 5552u : len;
     len -= amount;
-    while(amount > 0)
-    {
+    for(i = 0; i != amount; ++i) {
       s1 += (*data++);
       s2 += s1;
-      --amount;
     }
-    s1 %= 65521;
-    s2 %= 65521;
+    s1 %= 65521u;
+    s2 %= 65521u;
   }
 
-  return (s2 << 16) | s1;
+  return (s2 << 16u) | s1;
 }
 
 /*Return the adler32 of the bytes data[0..len-1]*/
-static unsigned adler32(const unsigned char* data, unsigned len)
-{
-  return update_adler32(1L, data, len);
+static unsigned adler32(const unsigned char* data, unsigned len) {
+  return update_adler32(1u, data, len);
 }
 
 /* ////////////////////////////////////////////////////////////////////////// */
@@ -2107,15 +2163,13 @@ static unsigned adler32(const unsigned char* data, unsigned len)
 #ifdef LODEPNG_COMPILE_DECODER
 
 unsigned lodepng_zlib_decompress(unsigned char** out, size_t* outsize, const unsigned char* in,
-                                 size_t insize, const LodePNGDecompressSettings* settings)
-{
+                                 size_t insize, const LodePNGDecompressSettings* settings) {
   unsigned error = 0;
   unsigned CM, CINFO, FDICT;
 
   if(insize < 2) return 53; /*error, size of zlib data too small*/
   /*read information from zlib header*/
-  if((in[0] * 256 + in[1]) % 31 != 0)
-  {
+  if((in[0] * 256 + in[1]) % 31 != 0) {
     /*error: 256 * in[0] + in[1] must be a multiple of 31, the FCHECK value is supposed to be made that way*/
     return 24;
   }
@@ -2126,13 +2180,11 @@ unsigned lodepng_zlib_decompress(unsigned char** out, size_t* outsize, const uns
   FDICT = (in[1] >> 5) & 1;
   /*FLEVEL = (in[1] >> 6) & 3;*/ /*FLEVEL is not used here*/
 
-  if(CM != 8 || CINFO > 7)
-  {
+  if(CM != 8 || CINFO > 7) {
     /*error: only compression method 8: inflate with sliding window of 32k is supported by the PNG spec*/
     return 25;
   }
-  if(FDICT != 0)
-  {
+  if(FDICT != 0) {
     /*error: the specification of PNG says about the zlib stream:
       "The additional flags shall not specify a preset dictionary."*/
     return 26;
@@ -2141,8 +2193,7 @@ unsigned lodepng_zlib_decompress(unsigned char** out, size_t* outsize, const uns
   error = inflate(out, outsize, in + 2, insize - 2, settings);
   if(error) return error;
 
-  if(!settings->ignore_adler32)
-  {
+  if(!settings->ignore_adler32) {
     unsigned ADLER32 = lodepng_read32bitInt(&in[insize - 4]);
     unsigned checksum = adler32(*out, (unsigned)(*outsize));
     if(checksum != ADLER32) return 58; /*error, adler checksum not correct, data must be corrupted*/
@@ -2152,14 +2203,10 @@ unsigned lodepng_zlib_decompress(unsigned char** out, size_t* outsize, const uns
 }
 
 static unsigned zlib_decompress(unsigned char** out, size_t* outsize, const unsigned char* in,
-                                size_t insize, const LodePNGDecompressSettings* settings)
-{
-  if(settings->custom_zlib)
-  {
+                                size_t insize, const LodePNGDecompressSettings* settings) {
+  if(settings->custom_zlib) {
     return settings->custom_zlib(out, outsize, in, insize, settings);
-  }
-  else
-  {
+  } else {
     return lodepng_zlib_decompress(out, outsize, in, insize, settings);
   }
 }
@@ -2169,56 +2216,48 @@ static unsigned zlib_decompress(unsigned char** out, size_t* outsize, const unsi
 #ifdef LODEPNG_COMPILE_ENCODER
 
 unsigned lodepng_zlib_compress(unsigned char** out, size_t* outsize, const unsigned char* in,
-                               size_t insize, const LodePNGCompressSettings* settings)
-{
-  /*initially, *out must be NULL and outsize 0, if you just give some random *out
-  that's pointing to a non allocated buffer, this'll crash*/
-  ucvector outv;
+                               size_t insize, const LodePNGCompressSettings* settings) {
   size_t i;
   unsigned error;
   unsigned char* deflatedata = 0;
   size_t deflatesize = 0;
 
-  /*zlib data: 1 byte CMF (CM+CINFO), 1 byte FLG, deflate data, 4 byte ADLER32 checksum of the Decompressed data*/
-  unsigned CMF = 120; /*0b01111000: CM 8, CINFO 7. With CINFO 7, any window size up to 32768 can be used.*/
-  unsigned FLEVEL = 0;
-  unsigned FDICT = 0;
-  unsigned CMFFLG = 256 * CMF + FDICT * 32 + FLEVEL * 64;
-  unsigned FCHECK = 31 - CMFFLG % 31;
-  CMFFLG += FCHECK;
-
-  /*ucvector-controlled version of the output buffer, for dynamic array*/
-  ucvector_init_buffer(&outv, *out, *outsize);
-
-  ucvector_push_back(&outv, (unsigned char)(CMFFLG >> 8));
-  ucvector_push_back(&outv, (unsigned char)(CMFFLG & 255));
-
   error = deflate(&deflatedata, &deflatesize, in, insize, settings);
 
-  if(!error)
-  {
-    unsigned ADLER32 = adler32(in, (unsigned)insize);
-    for(i = 0; i != deflatesize; ++i) ucvector_push_back(&outv, deflatedata[i]);
-    lodepng_free(deflatedata);
-    lodepng_add32bitInt(&outv, ADLER32);
+  *out = NULL;
+  *outsize = 0;
+  if(!error) {
+    *outsize = deflatesize + 6;
+    *out = (unsigned char*)lodepng_malloc(*outsize);
+    if(!out) error = 83; /*alloc fail*/
   }
 
-  *out = outv.data;
-  *outsize = outv.size;
+  if(!error) {
+    unsigned ADLER32 = adler32(in, (unsigned)insize);
+    /*zlib data: 1 byte CMF (CM+CINFO), 1 byte FLG, deflate data, 4 byte ADLER32 checksum of the Decompressed data*/
+    unsigned CMF = 120; /*0b01111000: CM 8, CINFO 7. With CINFO 7, any window size up to 32768 can be used.*/
+    unsigned FLEVEL = 0;
+    unsigned FDICT = 0;
+    unsigned CMFFLG = 256 * CMF + FDICT * 32 + FLEVEL * 64;
+    unsigned FCHECK = 31 - CMFFLG % 31;
+    CMFFLG += FCHECK;
 
+    (*out)[0] = (unsigned char)(CMFFLG >> 8);
+    (*out)[1] = (unsigned char)(CMFFLG & 255);
+    for(i = 0; i != deflatesize; ++i) (*out)[i + 2] = deflatedata[i];
+    lodepng_set32bitInt(&(*out)[*outsize - 4], ADLER32);
+  }
+
+  lodepng_free(deflatedata);
   return error;
 }
 
 /* compress using the default or custom zlib function */
 static unsigned zlib_compress(unsigned char** out, size_t* outsize, const unsigned char* in,
-                              size_t insize, const LodePNGCompressSettings* settings)
-{
-  if(settings->custom_zlib)
-  {
+                              size_t insize, const LodePNGCompressSettings* settings) {
+  if(settings->custom_zlib) {
     return settings->custom_zlib(out, outsize, in, insize, settings);
-  }
-  else
-  {
+  } else {
     return lodepng_zlib_compress(out, outsize, in, insize, settings);
   }
 }
@@ -2229,16 +2268,14 @@ static unsigned zlib_compress(unsigned char** out, size_t* outsize, const unsign
 
 #ifdef LODEPNG_COMPILE_DECODER
 static unsigned zlib_decompress(unsigned char** out, size_t* outsize, const unsigned char* in,
-                                size_t insize, const LodePNGDecompressSettings* settings)
-{
+                                size_t insize, const LodePNGDecompressSettings* settings) {
   if(!settings->custom_zlib) return 87; /*no custom zlib function provided */
   return settings->custom_zlib(out, outsize, in, insize, settings);
 }
 #endif /*LODEPNG_COMPILE_DECODER*/
 #ifdef LODEPNG_COMPILE_ENCODER
 static unsigned zlib_compress(unsigned char** out, size_t* outsize, const unsigned char* in,
-                              size_t insize, const LodePNGCompressSettings* settings)
-{
+                              size_t insize, const LodePNGCompressSettings* settings) {
   if(!settings->custom_zlib) return 87; /*no custom zlib function provided */
   return settings->custom_zlib(out, outsize, in, insize, settings);
 }
@@ -2253,8 +2290,7 @@ static unsigned zlib_compress(unsigned char** out, size_t* outsize, const unsign
 /*this is a good tradeoff between speed and compression ratio*/
 #define DEFAULT_WINDOWSIZE 2048
 
-void lodepng_compress_settings_init(LodePNGCompressSettings* settings)
-{
+void lodepng_compress_settings_init(LodePNGCompressSettings* settings) {
   /*compress with dynamic huffman tree (not in the mathematical sense, just not the predefined one)*/
   settings->btype = 2;
   settings->use_lz77 = 1;
@@ -2275,16 +2311,16 @@ const LodePNGCompressSettings lodepng_default_compress_settings = {2, 1, DEFAULT
 
 #ifdef LODEPNG_COMPILE_DECODER
 
-void lodepng_decompress_settings_init(LodePNGDecompressSettings* settings)
-{
+void lodepng_decompress_settings_init(LodePNGDecompressSettings* settings) {
   settings->ignore_adler32 = 0;
+  settings->ignore_nlen = 0;
 
   settings->custom_zlib = 0;
   settings->custom_inflate = 0;
   settings->custom_context = 0;
 }
 
-const LodePNGDecompressSettings lodepng_default_decompress_settings = {0, 0, 0, 0};
+const LodePNGDecompressSettings lodepng_default_decompress_settings = {0, 0, 0, 0, 0};
 
 #endif /*LODEPNG_COMPILE_DECODER*/
 
@@ -2339,13 +2375,11 @@ static unsigned lodepng_crc32_table[256] = {
 };
 
 /*Return the CRC of the bytes buf[0..len-1].*/
-unsigned lodepng_crc32(const unsigned char* data, size_t length)
-{
+unsigned lodepng_crc32(const unsigned char* data, size_t length) {
   unsigned r = 0xffffffffu;
   size_t i;
-  for(i = 0; i < length; ++i)
-  {
-    r = lodepng_crc32_table[(r ^ data[i]) & 0xff] ^ (r >> 8);
+  for(i = 0; i < length; ++i) {
+    r = lodepng_crc32_table[(r ^ data[i]) & 0xffu] ^ (r >> 8u);
   }
   return r ^ 0xffffffffu;
 }
@@ -2354,42 +2388,30 @@ unsigned lodepng_crc32(const unsigned char* data, size_t length);
 #endif /* !LODEPNG_NO_COMPILE_CRC */
 
 /* ////////////////////////////////////////////////////////////////////////// */
-/* / Reading and writing single bits and bytes from/to stream for LodePNG   / */
+/* / Reading and writing PNG color channel bits                             / */
 /* ////////////////////////////////////////////////////////////////////////// */
 
-static unsigned char readBitFromReversedStream(size_t* bitpointer, const unsigned char* bitstream)
-{
+/* The color channel bits of less-than-8-bit pixels are read with the MSB of bytes first,
+so LodePNGBitWriter and LodePNGBitReader can't be used for those. */
+
+static unsigned char readBitFromReversedStream(size_t* bitpointer, const unsigned char* bitstream) {
   unsigned char result = (unsigned char)((bitstream[(*bitpointer) >> 3] >> (7 - ((*bitpointer) & 0x7))) & 1);
   ++(*bitpointer);
   return result;
 }
 
-static unsigned readBitsFromReversedStream(size_t* bitpointer, const unsigned char* bitstream, size_t nbits)
-{
+/* TODO: make this faster */
+static unsigned readBitsFromReversedStream(size_t* bitpointer, const unsigned char* bitstream, size_t nbits) {
   unsigned result = 0;
   size_t i;
-  for(i = nbits - 1; i < nbits; --i)
-  {
-    result += (unsigned)readBitFromReversedStream(bitpointer, bitstream) << i;
+  for(i = 0 ; i < nbits; ++i) {
+    result <<= 1;
+    result |= (unsigned)readBitFromReversedStream(bitpointer, bitstream);
   }
   return result;
 }
 
-#ifdef LODEPNG_COMPILE_DECODER
-static void setBitOfReversedStream0(size_t* bitpointer, unsigned char* bitstream, unsigned char bit)
-{
-  /*the current bit in bitstream must be 0 for this to work*/
-  if(bit)
-  {
-    /*earlier bit of huffman code is in a lesser significant bit of an earlier byte*/
-    bitstream[(*bitpointer) >> 3] |= (bit << (7 - ((*bitpointer) & 0x7)));
-  }
-  ++(*bitpointer);
-}
-#endif /*LODEPNG_COMPILE_DECODER*/
-
-static void setBitOfReversedStream(size_t* bitpointer, unsigned char* bitstream, unsigned char bit)
-{
+static void setBitOfReversedStream(size_t* bitpointer, unsigned char* bitstream, unsigned char bit) {
   /*the current bit in bitstream may be 0 or 1 for this to work*/
   if(bit == 0) bitstream[(*bitpointer) >> 3] &=  (unsigned char)(~(1 << (7 - ((*bitpointer) & 0x7))));
   else         bitstream[(*bitpointer) >> 3] |=  (1 << (7 - ((*bitpointer) & 0x7)));
@@ -2400,51 +2422,42 @@ static void setBitOfReversedStream(size_t* bitpointer, unsigned char* bitstream,
 /* / PNG chunks                                                             / */
 /* ////////////////////////////////////////////////////////////////////////// */
 
-unsigned lodepng_chunk_length(const unsigned char* chunk)
-{
+unsigned lodepng_chunk_length(const unsigned char* chunk) {
   return lodepng_read32bitInt(&chunk[0]);
 }
 
-void lodepng_chunk_type(char type[5], const unsigned char* chunk)
-{
+void lodepng_chunk_type(char type[5], const unsigned char* chunk) {
   unsigned i;
   for(i = 0; i != 4; ++i) type[i] = (char)chunk[4 + i];
   type[4] = 0; /*null termination char*/
 }
 
-unsigned char lodepng_chunk_type_equals(const unsigned char* chunk, const char* type)
-{
-  if(strlen(type) != 4) return 0;
+unsigned char lodepng_chunk_type_equals(const unsigned char* chunk, const char* type) {
+  if(lodepng_strlen(type) != 4) return 0;
   return (chunk[4] == type[0] && chunk[5] == type[1] && chunk[6] == type[2] && chunk[7] == type[3]);
 }
 
-unsigned char lodepng_chunk_ancillary(const unsigned char* chunk)
-{
+unsigned char lodepng_chunk_ancillary(const unsigned char* chunk) {
   return((chunk[4] & 32) != 0);
 }
 
-unsigned char lodepng_chunk_private(const unsigned char* chunk)
-{
+unsigned char lodepng_chunk_private(const unsigned char* chunk) {
   return((chunk[6] & 32) != 0);
 }
 
-unsigned char lodepng_chunk_safetocopy(const unsigned char* chunk)
-{
+unsigned char lodepng_chunk_safetocopy(const unsigned char* chunk) {
   return((chunk[7] & 32) != 0);
 }
 
-unsigned char* lodepng_chunk_data(unsigned char* chunk)
-{
+unsigned char* lodepng_chunk_data(unsigned char* chunk) {
   return &chunk[8];
 }
 
-const unsigned char* lodepng_chunk_data_const(const unsigned char* chunk)
-{
+const unsigned char* lodepng_chunk_data_const(const unsigned char* chunk) {
   return &chunk[8];
 }
 
-unsigned lodepng_chunk_check_crc(const unsigned char* chunk)
-{
+unsigned lodepng_chunk_check_crc(const unsigned char* chunk) {
   unsigned length = lodepng_chunk_length(chunk);
   unsigned CRC = lodepng_read32bitInt(&chunk[length + 8]);
   /*the CRC is taken of the data and the 4 chunk type letters, not the length*/
@@ -2453,27 +2466,51 @@ unsigned lodepng_chunk_check_crc(const unsigned char* chunk)
   else return 0;
 }
 
-void lodepng_chunk_generate_crc(unsigned char* chunk)
-{
+void lodepng_chunk_generate_crc(unsigned char* chunk) {
   unsigned length = lodepng_chunk_length(chunk);
   unsigned CRC = lodepng_crc32(&chunk[4], length + 4);
   lodepng_set32bitInt(chunk + 8 + length, CRC);
 }
 
-unsigned char* lodepng_chunk_next(unsigned char* chunk)
-{
-  unsigned total_chunk_length = lodepng_chunk_length(chunk) + 12;
-  return &chunk[total_chunk_length];
+unsigned char* lodepng_chunk_next(unsigned char* chunk) {
+  if(chunk[0] == 0x89 && chunk[1] == 0x50 && chunk[2] == 0x4e && chunk[3] == 0x47
+    && chunk[4] == 0x0d && chunk[5] == 0x0a && chunk[6] == 0x1a && chunk[7] == 0x0a) {
+    /* Is PNG magic header at start of PNG file. Jump to first actual chunk. */
+    return chunk + 8;
+  } else {
+    unsigned total_chunk_length = lodepng_chunk_length(chunk) + 12;
+    return chunk + total_chunk_length;
+  }
 }
 
-const unsigned char* lodepng_chunk_next_const(const unsigned char* chunk)
-{
-  unsigned total_chunk_length = lodepng_chunk_length(chunk) + 12;
-  return &chunk[total_chunk_length];
+const unsigned char* lodepng_chunk_next_const(const unsigned char* chunk) {
+  if(chunk[0] == 0x89 && chunk[1] == 0x50 && chunk[2] == 0x4e && chunk[3] == 0x47
+    && chunk[4] == 0x0d && chunk[5] == 0x0a && chunk[6] == 0x1a && chunk[7] == 0x0a) {
+    /* Is PNG magic header at start of PNG file. Jump to first actual chunk. */
+    return chunk + 8;
+  } else {
+    unsigned total_chunk_length = lodepng_chunk_length(chunk) + 12;
+    return chunk + total_chunk_length;
+  }
 }
 
-unsigned lodepng_chunk_append(unsigned char** out, size_t* outlength, const unsigned char* chunk)
-{
+unsigned char* lodepng_chunk_find(unsigned char* chunk, const unsigned char* end, const char type[5]) {
+  for(;;) {
+    if(chunk + 12 >= end) return 0;
+    if(lodepng_chunk_type_equals(chunk, type)) return chunk;
+    chunk = lodepng_chunk_next(chunk);
+  }
+}
+
+const unsigned char* lodepng_chunk_find_const(const unsigned char* chunk, const unsigned char* end, const char type[5]) {
+  for(;;) {
+    if(chunk + 12 >= end) return 0;
+    if(lodepng_chunk_type_equals(chunk, type)) return chunk;
+    chunk = lodepng_chunk_next_const(chunk);
+  }
+}
+
+unsigned lodepng_chunk_append(unsigned char** out, size_t* outlength, const unsigned char* chunk) {
   unsigned i;
   unsigned total_chunk_length = lodepng_chunk_length(chunk) + 12;
   unsigned char *chunk_start, *new_buffer;
@@ -2492,8 +2529,7 @@ unsigned lodepng_chunk_append(unsigned char** out, size_t* outlength, const unsi
 }
 
 unsigned lodepng_chunk_create(unsigned char** out, size_t* outlength, unsigned length,
-                              const char* type, const unsigned char* data)
-{
+                              const char* type, const unsigned char* data) {
   unsigned i;
   unsigned char *chunk, *new_buffer;
   size_t new_length = (*outlength) + length + 12;
@@ -2523,47 +2559,42 @@ unsigned lodepng_chunk_create(unsigned char** out, size_t* outlength, unsigned l
 }
 
 /* ////////////////////////////////////////////////////////////////////////// */
-/* / Color types and such                                                   / */
+/* / Color types, channels, bits                                            / */
 /* ////////////////////////////////////////////////////////////////////////// */
 
-/*return type is a LodePNG error code*/
-static unsigned checkColorValidity(LodePNGColorType colortype, unsigned bd) /*bd = bitdepth*/
-{
-  switch(colortype)
-  {
-    case 0: if(!(bd == 1 || bd == 2 || bd == 4 || bd == 8 || bd == 16)) return 37; break; /*grey*/
-    case 2: if(!(                                 bd == 8 || bd == 16)) return 37; break; /*RGB*/
-    case 3: if(!(bd == 1 || bd == 2 || bd == 4 || bd == 8            )) return 37; break; /*palette*/
-    case 4: if(!(                                 bd == 8 || bd == 16)) return 37; break; /*grey + alpha*/
-    case 6: if(!(                                 bd == 8 || bd == 16)) return 37; break; /*RGBA*/
-    default: return 31;
+/*checks if the colortype is valid and the bitdepth bd is allowed for this colortype.
+Return value is a LodePNG error code.*/
+static unsigned checkColorValidity(LodePNGColorType colortype, unsigned bd) {
+  switch(colortype) {
+    case LCT_GREY:       if(!(bd == 1 || bd == 2 || bd == 4 || bd == 8 || bd == 16)) return 37; break;
+    case LCT_RGB:        if(!(                                 bd == 8 || bd == 16)) return 37; break;
+    case LCT_PALETTE:    if(!(bd == 1 || bd == 2 || bd == 4 || bd == 8            )) return 37; break;
+    case LCT_GREY_ALPHA: if(!(                                 bd == 8 || bd == 16)) return 37; break;
+    case LCT_RGBA:       if(!(                                 bd == 8 || bd == 16)) return 37; break;
+    default: return 31; /* invalid color type */
   }
   return 0; /*allowed color type / bits combination*/
 }
 
-static unsigned getNumColorChannels(LodePNGColorType colortype)
-{
-  switch(colortype)
-  {
-    case 0: return 1; /*grey*/
-    case 2: return 3; /*RGB*/
-    case 3: return 1; /*palette*/
-    case 4: return 2; /*grey + alpha*/
-    case 6: return 4; /*RGBA*/
+static unsigned getNumColorChannels(LodePNGColorType colortype) {
+  switch(colortype) {
+    case LCT_GREY: return 1;
+    case LCT_RGB: return 3;
+    case LCT_PALETTE: return 1;
+    case LCT_GREY_ALPHA: return 2;
+    case LCT_RGBA: return 4;
+    default: return 0; /*invalid color type*/
   }
-  return 0; /*unexisting color type*/
 }
 
-static unsigned lodepng_get_bpp_lct(LodePNGColorType colortype, unsigned bitdepth)
-{
+static unsigned lodepng_get_bpp_lct(LodePNGColorType colortype, unsigned bitdepth) {
   /*bits per pixel is amount of channels * bits per channel*/
   return getNumColorChannels(colortype) * bitdepth;
 }
 
 /* ////////////////////////////////////////////////////////////////////////// */
 
-void lodepng_color_mode_init(LodePNGColorMode* info)
-{
+void lodepng_color_mode_init(LodePNGColorMode* info) {
   info->key_defined = 0;
   info->key_r = info->key_g = info->key_b = 0;
   info->colortype = LCT_RGBA;
@@ -2572,18 +2603,31 @@ void lodepng_color_mode_init(LodePNGColorMode* info)
   info->palettesize = 0;
 }
 
-void lodepng_color_mode_cleanup(LodePNGColorMode* info)
-{
+void lodepng_color_mode_alloc_palette(LodePNGColorMode* info) {
+  size_t i;
+  /*room for 256 colors with 4 bytes each. Using realloc to avoid leak if it is being overwritten*/
+  info->palette = (unsigned char*)lodepng_realloc(info->palette, 1024);
+  if(!info->palette) return; /*alloc fail*/
+  for(i = 0; i != 256; ++i) {
+    /*Initialize all unused colors with black, the value used for invalid palette indices.
+    This is an error according to the PNG spec, but common PNG decoders make it black instead.
+    That makes color conversion slightly faster due to no error handling needed.*/
+    info->palette[i * 4 + 0] = 0;
+    info->palette[i * 4 + 1] = 0;
+    info->palette[i * 4 + 2] = 0;
+    info->palette[i * 4 + 3] = 255;
+  }
+}
+
+void lodepng_color_mode_cleanup(LodePNGColorMode* info) {
   lodepng_palette_clear(info);
 }
 
-unsigned lodepng_color_mode_copy(LodePNGColorMode* dest, const LodePNGColorMode* source)
-{
+unsigned lodepng_color_mode_copy(LodePNGColorMode* dest, const LodePNGColorMode* source) {
   size_t i;
   lodepng_color_mode_cleanup(dest);
   *dest = *source;
-  if(source->palette)
-  {
+  if(source->palette) {
     dest->palette = (unsigned char*)lodepng_malloc(1024);
     if(!dest->palette && source->palettesize) return 83; /*alloc fail*/
     for(i = 0; i != source->palettesize * 4; ++i) dest->palette[i] = source->palette[i];
@@ -2591,50 +2635,42 @@ unsigned lodepng_color_mode_copy(LodePNGColorMode* dest, const LodePNGColorMode*
   return 0;
 }
 
-static int lodepng_color_mode_equal(const LodePNGColorMode* a, const LodePNGColorMode* b)
-{
+LodePNGColorMode lodepng_color_mode_make(LodePNGColorType colortype, unsigned bitdepth) {
+  LodePNGColorMode result;
+  lodepng_color_mode_init(&result);
+  result.colortype = colortype;
+  result.bitdepth = bitdepth;
+  return result;
+}
+
+static int lodepng_color_mode_equal(const LodePNGColorMode* a, const LodePNGColorMode* b) {
   size_t i;
   if(a->colortype != b->colortype) return 0;
   if(a->bitdepth != b->bitdepth) return 0;
   if(a->key_defined != b->key_defined) return 0;
-  if(a->key_defined)
-  {
+  if(a->key_defined) {
     if(a->key_r != b->key_r) return 0;
     if(a->key_g != b->key_g) return 0;
     if(a->key_b != b->key_b) return 0;
   }
-  /*if one of the palette sizes is 0, then we consider it to be the same as the
-  other: it means that e.g. the palette was not given by the user and should be
-  considered the same as the palette inside the PNG.*/
-  if(1/*a->palettesize != 0 && b->palettesize != 0*/) {
-    if(a->palettesize != b->palettesize) return 0;
-    for(i = 0; i != a->palettesize * 4; ++i)
-    {
-      if(a->palette[i] != b->palette[i]) return 0;
-    }
+  if(a->palettesize != b->palettesize) return 0;
+  for(i = 0; i != a->palettesize * 4; ++i) {
+    if(a->palette[i] != b->palette[i]) return 0;
   }
   return 1;
 }
 
-void lodepng_palette_clear(LodePNGColorMode* info)
-{
+void lodepng_palette_clear(LodePNGColorMode* info) {
   if(info->palette) lodepng_free(info->palette);
   info->palette = 0;
   info->palettesize = 0;
 }
 
 unsigned lodepng_palette_add(LodePNGColorMode* info,
-                             unsigned char r, unsigned char g, unsigned char b, unsigned char a)
-{
-  unsigned char* data;
-  /*the same resize technique as C++ std::vectors is used, and here it's made so that for a palette with
-  the max of 256 colors, it'll have the exact alloc size*/
-  if(!info->palette) /*allocate palette if empty*/
-  {
-    /*room for 256 colors with 4 bytes each*/
-    data = (unsigned char*)lodepng_realloc(info->palette, 1024);
-    if(!data) return 83; /*alloc fail*/
-    else info->palette = data;
+                             unsigned char r, unsigned char g, unsigned char b, unsigned char a) {
+  if(!info->palette) /*allocate palette if empty*/ {
+    lodepng_color_mode_alloc_palette(info);
+    if(!info->palette) return 83; /*alloc fail*/
   }
   info->palette[4 * info->palettesize + 0] = r;
   info->palette[4 * info->palettesize + 1] = g;
@@ -2644,108 +2680,118 @@ unsigned lodepng_palette_add(LodePNGColorMode* info,
   return 0;
 }
 
-unsigned lodepng_get_bpp(const LodePNGColorMode* info)
-{
-  /*calculate bits per pixel out of colortype and bitdepth*/
+/*calculate bits per pixel out of colortype and bitdepth*/
+unsigned lodepng_get_bpp(const LodePNGColorMode* info) {
   return lodepng_get_bpp_lct(info->colortype, info->bitdepth);
 }
 
-unsigned lodepng_get_channels(const LodePNGColorMode* info)
-{
+unsigned lodepng_get_channels(const LodePNGColorMode* info) {
   return getNumColorChannels(info->colortype);
 }
 
-unsigned lodepng_is_greyscale_type(const LodePNGColorMode* info)
-{
+unsigned lodepng_is_greyscale_type(const LodePNGColorMode* info) {
   return info->colortype == LCT_GREY || info->colortype == LCT_GREY_ALPHA;
 }
 
-unsigned lodepng_is_alpha_type(const LodePNGColorMode* info)
-{
+unsigned lodepng_is_alpha_type(const LodePNGColorMode* info) {
   return (info->colortype & 4) != 0; /*4 or 6*/
 }
 
-unsigned lodepng_is_palette_type(const LodePNGColorMode* info)
-{
+unsigned lodepng_is_palette_type(const LodePNGColorMode* info) {
   return info->colortype == LCT_PALETTE;
 }
 
-unsigned lodepng_has_palette_alpha(const LodePNGColorMode* info)
-{
+unsigned lodepng_has_palette_alpha(const LodePNGColorMode* info) {
   size_t i;
-  for(i = 0; i != info->palettesize; ++i)
-  {
+  for(i = 0; i != info->palettesize; ++i) {
     if(info->palette[i * 4 + 3] < 255) return 1;
   }
   return 0;
 }
 
-unsigned lodepng_can_have_alpha(const LodePNGColorMode* info)
-{
+unsigned lodepng_can_have_alpha(const LodePNGColorMode* info) {
   return info->key_defined
       || lodepng_is_alpha_type(info)
       || lodepng_has_palette_alpha(info);
 }
 
-size_t lodepng_get_raw_size(unsigned w, unsigned h, const LodePNGColorMode* color)
-{
-  /*will not overflow for any color type if roughly w * h < 268435455*/
-  size_t bpp = lodepng_get_bpp(color);
-  size_t n = w * h;
-  return ((n / 8) * bpp) + ((n & 7) * bpp + 7) / 8;
+static size_t lodepng_get_raw_size_lct(unsigned w, unsigned h, LodePNGColorType colortype, unsigned bitdepth) {
+  size_t bpp = lodepng_get_bpp_lct(colortype, bitdepth);
+  size_t n = (size_t)w * (size_t)h;
+  return ((n / 8u) * bpp) + ((n & 7u) * bpp + 7u) / 8u;
 }
 
-size_t lodepng_get_raw_size_lct(unsigned w, unsigned h, LodePNGColorType colortype, unsigned bitdepth)
-{
-  /*will not overflow for any color type if roughly w * h < 268435455*/
-  size_t bpp = lodepng_get_bpp_lct(colortype, bitdepth);
-  size_t n = w * h;
-  return ((n / 8) * bpp) + ((n & 7) * bpp + 7) / 8;
+size_t lodepng_get_raw_size(unsigned w, unsigned h, const LodePNGColorMode* color) {
+  return lodepng_get_raw_size_lct(w, h, color->colortype, color->bitdepth);
 }
 
 
 #ifdef LODEPNG_COMPILE_PNG
 #ifdef LODEPNG_COMPILE_DECODER
-/*in an idat chunk, each scanline is a multiple of 8 bits, unlike the lodepng output buffer*/
-static size_t lodepng_get_raw_size_idat(unsigned w, unsigned h, const LodePNGColorMode* color)
-{
-  /*will not overflow for any color type if roughly w * h < 268435455*/
+
+/*in an idat chunk, each scanline is a multiple of 8 bits, unlike the lodepng output buffer,
+and in addition has one extra byte per line: the filter byte. So this gives a larger
+result than lodepng_get_raw_size. */
+static size_t lodepng_get_raw_size_idat(unsigned w, unsigned h, const LodePNGColorMode* color) {
   size_t bpp = lodepng_get_bpp(color);
-  size_t line = ((w / 8) * bpp) + ((w & 7) * bpp + 7) / 8;
-  return h * line;
+  /* + 1 for the filter byte, and possibly plus padding bits per line */
+  size_t line = ((size_t)(w / 8u) * bpp) + 1u + ((w & 7u) * bpp + 7u) / 8u;
+  return (size_t)h * line;
+}
+
+/*Safely checks whether size_t overflow can be caused due to amount of pixels.
+This check is overcautious rather than precise. If this check indicates no overflow,
+you can safely compute in a size_t (but not an unsigned):
+-(size_t)w * (size_t)h * 8
+-amount of bytes in IDAT (including filter, padding and Adam7 bytes)
+-amount of bytes in raw color model
+Returns 1 if overflow possible, 0 if not.
+*/
+static int lodepng_pixel_overflow(unsigned w, unsigned h,
+                                  const LodePNGColorMode* pngcolor, const LodePNGColorMode* rawcolor) {
+  size_t bpp = LODEPNG_MAX(lodepng_get_bpp(pngcolor), lodepng_get_bpp(rawcolor));
+  size_t numpixels, total;
+  size_t line; /* bytes per line in worst case */
+
+  if(lodepng_mulofl((size_t)w, (size_t)h, &numpixels)) return 1;
+  if(lodepng_mulofl(numpixels, 8, &total)) return 1; /* bit pointer with 8-bit color, or 8 bytes per channel color */
+
+  /* Bytes per scanline with the expression "(w / 8u) * bpp) + ((w & 7u) * bpp + 7u) / 8u" */
+  if(lodepng_mulofl((size_t)(w / 8u), bpp, &line)) return 1;
+  if(lodepng_addofl(line, ((w & 7u) * bpp + 7u) / 8u, &line)) return 1;
+
+  if(lodepng_addofl(line, 5, &line)) return 1; /* 5 bytes overhead per line: 1 filterbyte, 4 for Adam7 worst case */
+  if(lodepng_mulofl(line, h, &total)) return 1; /* Total bytes in worst case */
+
+  return 0; /* no overflow */
 }
 #endif /*LODEPNG_COMPILE_DECODER*/
 #endif /*LODEPNG_COMPILE_PNG*/
 
 #ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS
 
-static void LodePNGUnknownChunks_init(LodePNGInfo* info)
-{
+static void LodePNGUnknownChunks_init(LodePNGInfo* info) {
   unsigned i;
   for(i = 0; i != 3; ++i) info->unknown_chunks_data[i] = 0;
   for(i = 0; i != 3; ++i) info->unknown_chunks_size[i] = 0;
 }
 
-static void LodePNGUnknownChunks_cleanup(LodePNGInfo* info)
-{
+static void LodePNGUnknownChunks_cleanup(LodePNGInfo* info) {
   unsigned i;
   for(i = 0; i != 3; ++i) lodepng_free(info->unknown_chunks_data[i]);
 }
 
-static unsigned LodePNGUnknownChunks_copy(LodePNGInfo* dest, const LodePNGInfo* src)
-{
+static unsigned LodePNGUnknownChunks_copy(LodePNGInfo* dest, const LodePNGInfo* src) {
   unsigned i;
 
   LodePNGUnknownChunks_cleanup(dest);
 
-  for(i = 0; i != 3; ++i)
-  {
+  for(i = 0; i != 3; ++i) {
     size_t j;
     dest->unknown_chunks_size[i] = src->unknown_chunks_size[i];
     dest->unknown_chunks_data[i] = (unsigned char*)lodepng_malloc(src->unknown_chunks_size[i]);
     if(!dest->unknown_chunks_data[i] && dest->unknown_chunks_size[i]) return 83; /*alloc fail*/
-    for(j = 0; j < src->unknown_chunks_size[i]; ++j)
-    {
+    for(j = 0; j < src->unknown_chunks_size[i]; ++j) {
       dest->unknown_chunks_data[i][j] = src->unknown_chunks_data[i][j];
     }
   }
@@ -2755,18 +2801,15 @@ static unsigned LodePNGUnknownChunks_copy(LodePNGInfo* dest, const LodePNGInfo*
 
 /******************************************************************************/
 
-static void LodePNGText_init(LodePNGInfo* info)
-{
+static void LodePNGText_init(LodePNGInfo* info) {
   info->text_num = 0;
   info->text_keys = NULL;
   info->text_strings = NULL;
 }
 
-static void LodePNGText_cleanup(LodePNGInfo* info)
-{
+static void LodePNGText_cleanup(LodePNGInfo* info) {
   size_t i;
-  for(i = 0; i != info->text_num; ++i)
-  {
+  for(i = 0; i != info->text_num; ++i) {
     string_cleanup(&info->text_keys[i]);
     string_cleanup(&info->text_strings[i]);
   }
@@ -2774,30 +2817,25 @@ static void LodePNGText_cleanup(LodePNGInfo* info)
   lodepng_free(info->text_strings);
 }
 
-static unsigned LodePNGText_copy(LodePNGInfo* dest, const LodePNGInfo* source)
-{
+static unsigned LodePNGText_copy(LodePNGInfo* dest, const LodePNGInfo* source) {
   size_t i = 0;
   dest->text_keys = 0;
   dest->text_strings = 0;
   dest->text_num = 0;
-  for(i = 0; i != source->text_num; ++i)
-  {
+  for(i = 0; i != source->text_num; ++i) {
     CERROR_TRY_RETURN(lodepng_add_text(dest, source->text_keys[i], source->text_strings[i]));
   }
   return 0;
 }
 
-void lodepng_clear_text(LodePNGInfo* info)
-{
+void lodepng_clear_text(LodePNGInfo* info) {
   LodePNGText_cleanup(info);
 }
 
-unsigned lodepng_add_text(LodePNGInfo* info, const char* key, const char* str)
-{
+unsigned lodepng_add_text(LodePNGInfo* info, const char* key, const char* str) {
   char** new_keys = (char**)(lodepng_realloc(info->text_keys, sizeof(char*) * (info->text_num + 1)));
   char** new_strings = (char**)(lodepng_realloc(info->text_strings, sizeof(char*) * (info->text_num + 1)));
-  if(!new_keys || !new_strings)
-  {
+  if(!new_keys || !new_strings) {
     lodepng_free(new_keys);
     lodepng_free(new_strings);
     return 83; /*alloc fail*/
@@ -2807,19 +2845,15 @@ unsigned lodepng_add_text(LodePNGInfo* info, const char* key, const char* str)
   info->text_keys = new_keys;
   info->text_strings = new_strings;
 
-  string_init(&info->text_keys[info->text_num - 1]);
-  string_set(&info->text_keys[info->text_num - 1], key);
-
-  string_init(&info->text_strings[info->text_num - 1]);
-  string_set(&info->text_strings[info->text_num - 1], str);
+  info->text_keys[info->text_num - 1] = alloc_string(key);
+  info->text_strings[info->text_num - 1] = alloc_string(str);
 
   return 0;
 }
 
 /******************************************************************************/
 
-static void LodePNGIText_init(LodePNGInfo* info)
-{
+static void LodePNGIText_init(LodePNGInfo* info) {
   info->itext_num = 0;
   info->itext_keys = NULL;
   info->itext_langtags = NULL;
@@ -2827,11 +2861,9 @@ static void LodePNGIText_init(LodePNGInfo* info)
   info->itext_strings = NULL;
 }
 
-static void LodePNGIText_cleanup(LodePNGInfo* info)
-{
+static void LodePNGIText_cleanup(LodePNGInfo* info) {
   size_t i;
-  for(i = 0; i != info->itext_num; ++i)
-  {
+  for(i = 0; i != info->itext_num; ++i) {
     string_cleanup(&info->itext_keys[i]);
     string_cleanup(&info->itext_langtags[i]);
     string_cleanup(&info->itext_transkeys[i]);
@@ -2843,36 +2875,31 @@ static void LodePNGIText_cleanup(LodePNGInfo* info)
   lodepng_free(info->itext_strings);
 }
 
-static unsigned LodePNGIText_copy(LodePNGInfo* dest, const LodePNGInfo* source)
-{
+static unsigned LodePNGIText_copy(LodePNGInfo* dest, const LodePNGInfo* source) {
   size_t i = 0;
   dest->itext_keys = 0;
   dest->itext_langtags = 0;
   dest->itext_transkeys = 0;
   dest->itext_strings = 0;
   dest->itext_num = 0;
-  for(i = 0; i != source->itext_num; ++i)
-  {
+  for(i = 0; i != source->itext_num; ++i) {
     CERROR_TRY_RETURN(lodepng_add_itext(dest, source->itext_keys[i], source->itext_langtags[i],
                                         source->itext_transkeys[i], source->itext_strings[i]));
   }
   return 0;
 }
 
-void lodepng_clear_itext(LodePNGInfo* info)
-{
+void lodepng_clear_itext(LodePNGInfo* info) {
   LodePNGIText_cleanup(info);
 }
 
 unsigned lodepng_add_itext(LodePNGInfo* info, const char* key, const char* langtag,
-                           const char* transkey, const char* str)
-{
+                           const char* transkey, const char* str) {
   char** new_keys = (char**)(lodepng_realloc(info->itext_keys, sizeof(char*) * (info->itext_num + 1)));
   char** new_langtags = (char**)(lodepng_realloc(info->itext_langtags, sizeof(char*) * (info->itext_num + 1)));
   char** new_transkeys = (char**)(lodepng_realloc(info->itext_transkeys, sizeof(char*) * (info->itext_num + 1)));
   char** new_strings = (char**)(lodepng_realloc(info->itext_strings, sizeof(char*) * (info->itext_num + 1)));
-  if(!new_keys || !new_langtags || !new_transkeys || !new_strings)
-  {
+  if(!new_keys || !new_langtags || !new_transkeys || !new_strings) {
     lodepng_free(new_keys);
     lodepng_free(new_langtags);
     lodepng_free(new_transkeys);
@@ -2886,24 +2913,46 @@ unsigned lodepng_add_itext(LodePNGInfo* info, const char* key, const char* langt
   info->itext_transkeys = new_transkeys;
   info->itext_strings = new_strings;
 
-  string_init(&info->itext_keys[info->itext_num - 1]);
-  string_set(&info->itext_keys[info->itext_num - 1], key);
+  info->itext_keys[info->itext_num - 1] = alloc_string(key);
+  info->itext_langtags[info->itext_num - 1] = alloc_string(langtag);
+  info->itext_transkeys[info->itext_num - 1] = alloc_string(transkey);
+  info->itext_strings[info->itext_num - 1] = alloc_string(str);
+
+  return 0;
+}
 
-  string_init(&info->itext_langtags[info->itext_num - 1]);
-  string_set(&info->itext_langtags[info->itext_num - 1], langtag);
+/* same as set but does not delete */
+static unsigned lodepng_assign_icc(LodePNGInfo* info, const char* name, const unsigned char* profile, unsigned profile_size) {
+  if(profile_size == 0) return 100; /*invalid ICC profile size*/
 
-  string_init(&info->itext_transkeys[info->itext_num - 1]);
-  string_set(&info->itext_transkeys[info->itext_num - 1], transkey);
+  info->iccp_name = alloc_string(name);
+  info->iccp_profile = (unsigned char*)lodepng_malloc(profile_size);
 
-  string_init(&info->itext_strings[info->itext_num - 1]);
-  string_set(&info->itext_strings[info->itext_num - 1], str);
+  if(!info->iccp_name || !info->iccp_profile) return 83; /*alloc fail*/
 
-  return 0;
+  lodepng_memcpy(info->iccp_profile, profile, profile_size);
+  info->iccp_profile_size = profile_size;
+
+  return 0; /*ok*/
+}
+
+unsigned lodepng_set_icc(LodePNGInfo* info, const char* name, const unsigned char* profile, unsigned profile_size) {
+  if(info->iccp_name) lodepng_clear_icc(info);
+  info->iccp_defined = 1;
+
+  return lodepng_assign_icc(info, name, profile, profile_size);
+}
+
+void lodepng_clear_icc(LodePNGInfo* info) {
+  string_cleanup(&info->iccp_name);
+  lodepng_free(info->iccp_profile);
+  info->iccp_profile = NULL;
+  info->iccp_profile_size = 0;
+  info->iccp_defined = 0;
 }
 #endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/
 
-void lodepng_info_init(LodePNGInfo* info)
-{
+void lodepng_info_init(LodePNGInfo* info) {
   lodepng_color_mode_init(&info->color);
   info->interlace_method = 0;
   info->compression_method = 0;
@@ -2918,23 +2967,30 @@ void lodepng_info_init(LodePNGInfo* info)
   info->time_defined = 0;
   info->phys_defined = 0;
 
+  info->gama_defined = 0;
+  info->chrm_defined = 0;
+  info->srgb_defined = 0;
+  info->iccp_defined = 0;
+  info->iccp_name = NULL;
+  info->iccp_profile = NULL;
+
   LodePNGUnknownChunks_init(info);
 #endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/
 }
 
-void lodepng_info_cleanup(LodePNGInfo* info)
-{
+void lodepng_info_cleanup(LodePNGInfo* info) {
   lodepng_color_mode_cleanup(&info->color);
 #ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS
   LodePNGText_cleanup(info);
   LodePNGIText_cleanup(info);
 
+  lodepng_clear_icc(info);
+
   LodePNGUnknownChunks_cleanup(info);
 #endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/
 }
 
-unsigned lodepng_info_copy(LodePNGInfo* dest, const LodePNGInfo* source)
-{
+unsigned lodepng_info_copy(LodePNGInfo* dest, const LodePNGInfo* source) {
   lodepng_info_cleanup(dest);
   *dest = *source;
   lodepng_color_mode_init(&dest->color);
@@ -2943,6 +2999,9 @@ unsigned lodepng_info_copy(LodePNGInfo* dest, const LodePNGInfo* source)
 #ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS
   CERROR_TRY_RETURN(LodePNGText_copy(dest, source));
   CERROR_TRY_RETURN(LodePNGIText_copy(dest, source));
+  if(source->iccp_defined) {
+    CERROR_TRY_RETURN(lodepng_assign_icc(dest, source->iccp_name, source->iccp_profile, source->iccp_profile_size));
+  }
 
   LodePNGUnknownChunks_init(dest);
   CERROR_TRY_RETURN(LodePNGUnknownChunks_copy(dest, source));
@@ -2950,25 +3009,17 @@ unsigned lodepng_info_copy(LodePNGInfo* dest, const LodePNGInfo* source)
   return 0;
 }
 
-void lodepng_info_swap(LodePNGInfo* a, LodePNGInfo* b)
-{
-  LodePNGInfo temp = *a;
-  *a = *b;
-  *b = temp;
-}
-
 /* ////////////////////////////////////////////////////////////////////////// */
 
 /*index: bitgroup index, bits: bitgroup size(1, 2 or 4), in: bitgroup value, out: octet array to add bits to*/
-static void addColorBits(unsigned char* out, size_t index, unsigned bits, unsigned in)
-{
+static void addColorBits(unsigned char* out, size_t index, unsigned bits, unsigned in) {
   unsigned m = bits == 1 ? 7 : bits == 2 ? 3 : 1; /*8 / bits - 1*/
   /*p = the partial index in the byte, e.g. with 4 palettebits it is 0 for first half or 1 for second half*/
   unsigned p = index & m;
   in &= (1u << bits) - 1u; /*filter out any other bits of the input value*/
   in = in << (bits * (m - p));
-  if(p == 0) out[index * bits / 8] = in;
-  else out[index * bits / 8] |= in;
+  if(p == 0) out[index * bits / 8u] = in;
+  else out[index * bits / 8u] |= in;
 }
 
 typedef struct ColorTree ColorTree;
@@ -2979,26 +3030,21 @@ This is the data structure used to count the number of unique colors and to get
 index for a color. It's like an octree, but because the alpha channel is used too, each
 node has 16 instead of 8 children.
 */
-struct ColorTree
-{
+struct ColorTree {
   ColorTree* children[16]; /*up to 16 pointers to ColorTree of next level*/
   int index; /*the payload. Only has a meaningful value if this is in the last level*/
 };
 
-static void color_tree_init(ColorTree* tree)
-{
+static void color_tree_init(ColorTree* tree) {
   int i;
   for(i = 0; i != 16; ++i) tree->children[i] = 0;
   tree->index = -1;
 }
 
-static void color_tree_cleanup(ColorTree* tree)
-{
+static void color_tree_cleanup(ColorTree* tree) {
   int i;
-  for(i = 0; i != 16; ++i)
-  {
-    if(tree->children[i])
-    {
+  for(i = 0; i != 16; ++i) {
+    if(tree->children[i]) {
       color_tree_cleanup(tree->children[i]);
       lodepng_free(tree->children[i]);
     }
@@ -3006,11 +3052,9 @@ static void color_tree_cleanup(ColorTree* tree)
 }
 
 /*returns -1 if color not present, its index otherwise*/
-static int color_tree_get(ColorTree* tree, unsigned char r, unsigned char g, unsigned char b, unsigned char a)
-{
+static int color_tree_get(ColorTree* tree, unsigned char r, unsigned char g, unsigned char b, unsigned char a) {
   int bit = 0;
-  for(bit = 0; bit < 8; ++bit)
-  {
+  for(bit = 0; bit < 8; ++bit) {
     int i = 8 * ((r >> bit) & 1) + 4 * ((g >> bit) & 1) + 2 * ((b >> bit) & 1) + 1 * ((a >> bit) & 1);
     if(!tree->children[i]) return -1;
     else tree = tree->children[i];
@@ -3019,8 +3063,7 @@ static int color_tree_get(ColorTree* tree, unsigned char r, unsigned char g, uns
 }
 
 #ifdef LODEPNG_COMPILE_ENCODER
-static int color_tree_has(ColorTree* tree, unsigned char r, unsigned char g, unsigned char b, unsigned char a)
-{
+static int color_tree_has(ColorTree* tree, unsigned char r, unsigned char g, unsigned char b, unsigned char a) {
   return color_tree_get(tree, r, g, b, a) >= 0;
 }
 #endif /*LODEPNG_COMPILE_ENCODER*/
@@ -3028,14 +3071,11 @@ static int color_tree_has(ColorTree* tree, unsigned char r, unsigned char g, uns
 /*color is not allowed to already exist.
 Index should be >= 0 (it's signed to be compatible with using -1 for "doesn't exist")*/
 static void color_tree_add(ColorTree* tree,
-                           unsigned char r, unsigned char g, unsigned char b, unsigned char a, unsigned index)
-{
+                           unsigned char r, unsigned char g, unsigned char b, unsigned char a, unsigned index) {
   int bit;
-  for(bit = 0; bit < 8; ++bit)
-  {
+  for(bit = 0; bit < 8; ++bit) {
     int i = 8 * ((r >> bit) & 1) + 4 * ((g >> bit) & 1) + 2 * ((b >> bit) & 1) + 1 * ((a >> bit) & 1);
-    if(!tree->children[i])
-    {
+    if(!tree->children[i]) {
       tree->children[i] = (ColorTree*)lodepng_malloc(sizeof(ColorTree));
       color_tree_init(tree->children[i]);
     }
@@ -3047,67 +3087,47 @@ static void color_tree_add(ColorTree* tree,
 /*put a pixel, given its RGBA color, into image of any color type*/
 static unsigned rgba8ToPixel(unsigned char* out, size_t i,
                              const LodePNGColorMode* mode, ColorTree* tree /*for palette*/,
-                             unsigned char r, unsigned char g, unsigned char b, unsigned char a)
-{
-  if(mode->colortype == LCT_GREY)
-  {
-    unsigned char grey = r; /*((unsigned short)r + g + b) / 3*/;
-    if(mode->bitdepth == 8) out[i] = grey;
-    else if(mode->bitdepth == 16) out[i * 2 + 0] = out[i * 2 + 1] = grey;
-    else
-    {
-      /*take the most significant bits of grey*/
-      grey = (grey >> (8 - mode->bitdepth)) & ((1 << mode->bitdepth) - 1);
-      addColorBits(out, i, mode->bitdepth, grey);
-    }
-  }
-  else if(mode->colortype == LCT_RGB)
-  {
-    if(mode->bitdepth == 8)
-    {
+                             unsigned char r, unsigned char g, unsigned char b, unsigned char a) {
+  if(mode->colortype == LCT_GREY) {
+    unsigned char gray = r; /*((unsigned short)r + g + b) / 3u;*/
+    if(mode->bitdepth == 8) out[i] = gray;
+    else if(mode->bitdepth == 16) out[i * 2 + 0] = out[i * 2 + 1] = gray;
+    else {
+      /*take the most significant bits of gray*/
+      gray = (gray >> (8 - mode->bitdepth)) & ((1 << mode->bitdepth) - 1);
+      addColorBits(out, i, mode->bitdepth, gray);
+    }
+  } else if(mode->colortype == LCT_RGB) {
+    if(mode->bitdepth == 8) {
       out[i * 3 + 0] = r;
       out[i * 3 + 1] = g;
       out[i * 3 + 2] = b;
-    }
-    else
-    {
+    } else {
       out[i * 6 + 0] = out[i * 6 + 1] = r;
       out[i * 6 + 2] = out[i * 6 + 3] = g;
       out[i * 6 + 4] = out[i * 6 + 5] = b;
     }
-  }
-  else if(mode->colortype == LCT_PALETTE)
-  {
+  } else if(mode->colortype == LCT_PALETTE) {
     int index = color_tree_get(tree, r, g, b, a);
     if(index < 0) return 82; /*color not in palette*/
     if(mode->bitdepth == 8) out[i] = index;
     else addColorBits(out, i, mode->bitdepth, (unsigned)index);
-  }
-  else if(mode->colortype == LCT_GREY_ALPHA)
-  {
-    unsigned char grey = r; /*((unsigned short)r + g + b) / 3*/;
-    if(mode->bitdepth == 8)
-    {
-      out[i * 2 + 0] = grey;
+  } else if(mode->colortype == LCT_GREY_ALPHA) {
+    unsigned char gray = r; /*((unsigned short)r + g + b) / 3u;*/
+    if(mode->bitdepth == 8) {
+      out[i * 2 + 0] = gray;
       out[i * 2 + 1] = a;
-    }
-    else if(mode->bitdepth == 16)
-    {
-      out[i * 4 + 0] = out[i * 4 + 1] = grey;
+    } else if(mode->bitdepth == 16) {
+      out[i * 4 + 0] = out[i * 4 + 1] = gray;
       out[i * 4 + 2] = out[i * 4 + 3] = a;
     }
-  }
-  else if(mode->colortype == LCT_RGBA)
-  {
-    if(mode->bitdepth == 8)
-    {
+  } else if(mode->colortype == LCT_RGBA) {
+    if(mode->bitdepth == 8) {
       out[i * 4 + 0] = r;
       out[i * 4 + 1] = g;
       out[i * 4 + 2] = b;
       out[i * 4 + 3] = a;
-    }
-    else
-    {
+    } else {
       out[i * 8 + 0] = out[i * 8 + 1] = r;
       out[i * 8 + 2] = out[i * 8 + 3] = g;
       out[i * 8 + 4] = out[i * 8 + 5] = b;
@@ -3121,33 +3141,25 @@ static unsigned rgba8ToPixel(unsigned char* out, size_t i,
 /*put a pixel, given its RGBA16 color, into image of any color 16-bitdepth type*/
 static void rgba16ToPixel(unsigned char* out, size_t i,
                          const LodePNGColorMode* mode,
-                         unsigned short r, unsigned short g, unsigned short b, unsigned short a)
-{
-  if(mode->colortype == LCT_GREY)
-  {
-    unsigned short grey = r; /*((unsigned)r + g + b) / 3*/;
-    out[i * 2 + 0] = (grey >> 8) & 255;
-    out[i * 2 + 1] = grey & 255;
-  }
-  else if(mode->colortype == LCT_RGB)
-  {
+                         unsigned short r, unsigned short g, unsigned short b, unsigned short a) {
+  if(mode->colortype == LCT_GREY) {
+    unsigned short gray = r; /*((unsigned)r + g + b) / 3u;*/
+    out[i * 2 + 0] = (gray >> 8) & 255;
+    out[i * 2 + 1] = gray & 255;
+  } else if(mode->colortype == LCT_RGB) {
     out[i * 6 + 0] = (r >> 8) & 255;
     out[i * 6 + 1] = r & 255;
     out[i * 6 + 2] = (g >> 8) & 255;
     out[i * 6 + 3] = g & 255;
     out[i * 6 + 4] = (b >> 8) & 255;
     out[i * 6 + 5] = b & 255;
-  }
-  else if(mode->colortype == LCT_GREY_ALPHA)
-  {
-    unsigned short grey = r; /*((unsigned)r + g + b) / 3*/;
-    out[i * 4 + 0] = (grey >> 8) & 255;
-    out[i * 4 + 1] = grey & 255;
+  } else if(mode->colortype == LCT_GREY_ALPHA) {
+    unsigned short gray = r; /*((unsigned)r + g + b) / 3u;*/
+    out[i * 4 + 0] = (gray >> 8) & 255;
+    out[i * 4 + 1] = gray & 255;
     out[i * 4 + 2] = (a >> 8) & 255;
     out[i * 4 + 3] = a & 255;
-  }
-  else if(mode->colortype == LCT_RGBA)
-  {
+  } else if(mode->colortype == LCT_RGBA) {
     out[i * 8 + 0] = (r >> 8) & 255;
     out[i * 8 + 1] = r & 255;
     out[i * 8 + 2] = (g >> 8) & 255;
@@ -3163,24 +3175,17 @@ static void rgba16ToPixel(unsigned char* out, size_t i,
 static void getPixelColorRGBA8(unsigned char* r, unsigned char* g,
                                unsigned char* b, unsigned char* a,
                                const unsigned char* in, size_t i,
-                               const LodePNGColorMode* mode)
-{
-  if(mode->colortype == LCT_GREY)
-  {
-    if(mode->bitdepth == 8)
-    {
+                               const LodePNGColorMode* mode) {
+  if(mode->colortype == LCT_GREY) {
+    if(mode->bitdepth == 8) {
       *r = *g = *b = in[i];
       if(mode->key_defined && *r == mode->key_r) *a = 0;
       else *a = 255;
-    }
-    else if(mode->bitdepth == 16)
-    {
+    } else if(mode->bitdepth == 16) {
       *r = *g = *b = in[i * 2 + 0];
       if(mode->key_defined && 256U * in[i * 2 + 0] + in[i * 2 + 1] == mode->key_r) *a = 0;
       else *a = 255;
-    }
-    else
-    {
+    } else {
       unsigned highest = ((1U << mode->bitdepth) - 1U); /*highest possible value for this bit depth*/
       size_t j = i * mode->bitdepth;
       unsigned value = readBitsFromReversedStream(&j, in, mode->bitdepth);
@@ -3188,17 +3193,12 @@ static void getPixelColorRGBA8(unsigned char* r, unsigned char* g,
       if(mode->key_defined && value == mode->key_r) *a = 0;
       else *a = 255;
     }
-  }
-  else if(mode->colortype == LCT_RGB)
-  {
-    if(mode->bitdepth == 8)
-    {
+  } else if(mode->colortype == LCT_RGB) {
+    if(mode->bitdepth == 8) {
       *r = in[i * 3 + 0]; *g = in[i * 3 + 1]; *b = in[i * 3 + 2];
       if(mode->key_defined && *r == mode->key_r && *g == mode->key_g && *b == mode->key_b) *a = 0;
       else *a = 255;
-    }
-    else
-    {
+    } else {
       *r = in[i * 6 + 0];
       *g = in[i * 6 + 2];
       *b = in[i * 6 + 4];
@@ -3207,56 +3207,33 @@ static void getPixelColorRGBA8(unsigned char* r, unsigned char* g,
          && 256U * in[i * 6 + 4] + in[i * 6 + 5] == mode->key_b) *a = 0;
       else *a = 255;
     }
-  }
-  else if(mode->colortype == LCT_PALETTE)
-  {
+  } else if(mode->colortype == LCT_PALETTE) {
     unsigned index;
     if(mode->bitdepth == 8) index = in[i];
-    else
-    {
+    else {
       size_t j = i * mode->bitdepth;
       index = readBitsFromReversedStream(&j, in, mode->bitdepth);
     }
-
-    if(index >= mode->palettesize)
-    {
-      /*This is an error according to the PNG spec, but common PNG decoders make it black instead.
-      Done here too, slightly faster due to no error handling needed.*/
-      *r = *g = *b = 0;
-      *a = 255;
-    }
-    else
-    {
-      *r = mode->palette[index * 4 + 0];
-      *g = mode->palette[index * 4 + 1];
-      *b = mode->palette[index * 4 + 2];
-      *a = mode->palette[index * 4 + 3];
-    }
-  }
-  else if(mode->colortype == LCT_GREY_ALPHA)
-  {
-    if(mode->bitdepth == 8)
-    {
+    /*out of bounds of palette not checked: see lodepng_color_mode_alloc_palette.*/
+    *r = mode->palette[index * 4 + 0];
+    *g = mode->palette[index * 4 + 1];
+    *b = mode->palette[index * 4 + 2];
+    *a = mode->palette[index * 4 + 3];
+  } else if(mode->colortype == LCT_GREY_ALPHA) {
+    if(mode->bitdepth == 8) {
       *r = *g = *b = in[i * 2 + 0];
       *a = in[i * 2 + 1];
-    }
-    else
-    {
+    } else {
       *r = *g = *b = in[i * 4 + 0];
       *a = in[i * 4 + 2];
     }
-  }
-  else if(mode->colortype == LCT_RGBA)
-  {
-    if(mode->bitdepth == 8)
-    {
+  } else if(mode->colortype == LCT_RGBA) {
+    if(mode->bitdepth == 8) {
       *r = in[i * 4 + 0];
       *g = in[i * 4 + 1];
       *b = in[i * 4 + 2];
       *a = in[i * 4 + 3];
-    }
-    else
-    {
+    } else {
       *r = in[i * 8 + 0];
       *g = in[i * 8 + 2];
       *b = in[i * 8 + 4];
@@ -3267,136 +3244,171 @@ static void getPixelColorRGBA8(unsigned char* r, unsigned char* g,
 
 /*Similar to getPixelColorRGBA8, but with all the for loops inside of the color
 mode test cases, optimized to convert the colors much faster, when converting
-to RGBA or RGB with 8 bit per cannel. buffer must be RGBA or RGB output with
-enough memory, if has_alpha is true the output is RGBA. mode has the color mode
-of the input buffer.*/
-static void getPixelColorsRGBA8(unsigned char* buffer, size_t numpixels,
-                                unsigned has_alpha, const unsigned char* in,
-                                const LodePNGColorMode* mode)
-{
-  unsigned num_channels = has_alpha ? 4 : 3;
+to the common case of RGBA with 8 bit per channel. buffer must be RGBA with
+enough memory.*/
+static void getPixelColorsRGBA8(unsigned char* LODEPNG_RESTRICT buffer, size_t numpixels,
+                                const unsigned char* LODEPNG_RESTRICT in,
+                                const LodePNGColorMode* mode) {
+  unsigned num_channels = 4;
   size_t i;
-  if(mode->colortype == LCT_GREY)
-  {
-    if(mode->bitdepth == 8)
-    {
-      for(i = 0; i != numpixels; ++i, buffer += num_channels)
-      {
+  if(mode->colortype == LCT_GREY) {
+    if(mode->bitdepth == 8) {
+      for(i = 0; i != numpixels; ++i, buffer += num_channels) {
         buffer[0] = buffer[1] = buffer[2] = in[i];
-        if(has_alpha) buffer[3] = mode->key_defined && in[i] == mode->key_r ? 0 : 255;
+        buffer[3] = 255;
       }
-    }
-    else if(mode->bitdepth == 16)
-    {
-      for(i = 0; i != numpixels; ++i, buffer += num_channels)
-      {
+      if(mode->key_defined) {
+        buffer -= numpixels * num_channels;
+        for(i = 0; i != numpixels; ++i, buffer += num_channels) {
+          if(buffer[0] == mode->key_r) buffer[3] = 0;
+        }
+      }
+    } else if(mode->bitdepth == 16) {
+      for(i = 0; i != numpixels; ++i, buffer += num_channels) {
         buffer[0] = buffer[1] = buffer[2] = in[i * 2];
-        if(has_alpha) buffer[3] = mode->key_defined && 256U * in[i * 2 + 0] + in[i * 2 + 1] == mode->key_r ? 0 : 255;
+        buffer[3] = mode->key_defined && 256U * in[i * 2 + 0] + in[i * 2 + 1] == mode->key_r ? 0 : 255;
       }
-    }
-    else
-    {
+    } else {
       unsigned highest = ((1U << mode->bitdepth) - 1U); /*highest possible value for this bit depth*/
       size_t j = 0;
-      for(i = 0; i != numpixels; ++i, buffer += num_channels)
-      {
+      for(i = 0; i != numpixels; ++i, buffer += num_channels) {
         unsigned value = readBitsFromReversedStream(&j, in, mode->bitdepth);
         buffer[0] = buffer[1] = buffer[2] = (value * 255) / highest;
-        if(has_alpha) buffer[3] = mode->key_defined && value == mode->key_r ? 0 : 255;
+        buffer[3] = mode->key_defined && value == mode->key_r ? 0 : 255;
       }
     }
-  }
-  else if(mode->colortype == LCT_RGB)
-  {
-    if(mode->bitdepth == 8)
-    {
-      for(i = 0; i != numpixels; ++i, buffer += num_channels)
-      {
-        buffer[0] = in[i * 3 + 0];
-        buffer[1] = in[i * 3 + 1];
-        buffer[2] = in[i * 3 + 2];
-        if(has_alpha) buffer[3] = mode->key_defined && buffer[0] == mode->key_r
-           && buffer[1]== mode->key_g && buffer[2] == mode->key_b ? 0 : 255;
+  } else if(mode->colortype == LCT_RGB) {
+    if(mode->bitdepth == 8) {
+      for(i = 0; i != numpixels; ++i, buffer += num_channels) {
+        lodepng_memcpy(buffer, &in[i * 3], 3);
+        buffer[3] = 255;
       }
-    }
-    else
-    {
-      for(i = 0; i != numpixels; ++i, buffer += num_channels)
-      {
+      if(mode->key_defined) {
+        buffer -= numpixels * num_channels;
+        for(i = 0; i != numpixels; ++i, buffer += num_channels) {
+          if(buffer[0] == mode->key_r && buffer[1]== mode->key_g && buffer[2] == mode->key_b) buffer[3] = 0;
+        }
+      }
+    } else {
+      for(i = 0; i != numpixels; ++i, buffer += num_channels) {
         buffer[0] = in[i * 6 + 0];
         buffer[1] = in[i * 6 + 2];
         buffer[2] = in[i * 6 + 4];
-        if(has_alpha) buffer[3] = mode->key_defined
+        buffer[3] = mode->key_defined
            && 256U * in[i * 6 + 0] + in[i * 6 + 1] == mode->key_r
            && 256U * in[i * 6 + 2] + in[i * 6 + 3] == mode->key_g
            && 256U * in[i * 6 + 4] + in[i * 6 + 5] == mode->key_b ? 0 : 255;
       }
     }
-  }
-  else if(mode->colortype == LCT_PALETTE)
-  {
-    unsigned index;
-    size_t j = 0;
-    for(i = 0; i != numpixels; ++i, buffer += num_channels)
-    {
-      if(mode->bitdepth == 8) index = in[i];
-      else index = readBitsFromReversedStream(&j, in, mode->bitdepth);
-
-      if(index >= mode->palettesize)
-      {
-        /*This is an error according to the PNG spec, but most PNG decoders make it black instead.
-        Done here too, slightly faster due to no error handling needed.*/
-        buffer[0] = buffer[1] = buffer[2] = 0;
-        if(has_alpha) buffer[3] = 255;
+  } else if(mode->colortype == LCT_PALETTE) {
+    if(mode->bitdepth == 8) {
+      for(i = 0; i != numpixels; ++i, buffer += num_channels) {
+        unsigned index = in[i];
+        /*out of bounds of palette not checked: see lodepng_color_mode_alloc_palette.*/
+        lodepng_memcpy(buffer, &mode->palette[index * 4], 4);
       }
-      else
-      {
-        buffer[0] = mode->palette[index * 4 + 0];
-        buffer[1] = mode->palette[index * 4 + 1];
-        buffer[2] = mode->palette[index * 4 + 2];
-        if(has_alpha) buffer[3] = mode->palette[index * 4 + 3];
+    } else {
+      size_t j = 0;
+      for(i = 0; i != numpixels; ++i, buffer += num_channels) {
+        unsigned index = readBitsFromReversedStream(&j, in, mode->bitdepth);
+        /*out of bounds of palette not checked: see lodepng_color_mode_alloc_palette.*/
+        lodepng_memcpy(buffer, &mode->palette[index * 4], 4);
       }
     }
-  }
-  else if(mode->colortype == LCT_GREY_ALPHA)
-  {
-    if(mode->bitdepth == 8)
-    {
-      for(i = 0; i != numpixels; ++i, buffer += num_channels)
-      {
+  } else if(mode->colortype == LCT_GREY_ALPHA) {
+    if(mode->bitdepth == 8) {
+      for(i = 0; i != numpixels; ++i, buffer += num_channels) {
         buffer[0] = buffer[1] = buffer[2] = in[i * 2 + 0];
-        if(has_alpha) buffer[3] = in[i * 2 + 1];
+        buffer[3] = in[i * 2 + 1];
       }
-    }
-    else
-    {
-      for(i = 0; i != numpixels; ++i, buffer += num_channels)
-      {
+    } else {
+      for(i = 0; i != numpixels; ++i, buffer += num_channels) {
         buffer[0] = buffer[1] = buffer[2] = in[i * 4 + 0];
-        if(has_alpha) buffer[3] = in[i * 4 + 2];
+        buffer[3] = in[i * 4 + 2];
+      }
+    }
+  } else if(mode->colortype == LCT_RGBA) {
+    if(mode->bitdepth == 8) {
+      lodepng_memcpy(buffer, in, numpixels * 4);
+    } else {
+      for(i = 0; i != numpixels; ++i, buffer += num_channels) {
+        buffer[0] = in[i * 8 + 0];
+        buffer[1] = in[i * 8 + 2];
+        buffer[2] = in[i * 8 + 4];
+        buffer[3] = in[i * 8 + 6];
       }
     }
   }
-  else if(mode->colortype == LCT_RGBA)
-  {
-    if(mode->bitdepth == 8)
-    {
-      for(i = 0; i != numpixels; ++i, buffer += num_channels)
-      {
-        buffer[0] = in[i * 4 + 0];
-        buffer[1] = in[i * 4 + 1];
-        buffer[2] = in[i * 4 + 2];
-        if(has_alpha) buffer[3] = in[i * 4 + 3];
+}
+
+/*Similar to getPixelColorsRGBA8, but with 3-channel RGB output.*/
+static void getPixelColorsRGB8(unsigned char* LODEPNG_RESTRICT buffer, size_t numpixels,
+                               const unsigned char* LODEPNG_RESTRICT in,
+                               const LodePNGColorMode* mode) {
+  const unsigned num_channels = 3;
+  size_t i;
+  if(mode->colortype == LCT_GREY) {
+    if(mode->bitdepth == 8) {
+      for(i = 0; i != numpixels; ++i, buffer += num_channels) {
+        buffer[0] = buffer[1] = buffer[2] = in[i];
+      }
+    } else if(mode->bitdepth == 16) {
+      for(i = 0; i != numpixels; ++i, buffer += num_channels) {
+        buffer[0] = buffer[1] = buffer[2] = in[i * 2];
+      }
+    } else {
+      unsigned highest = ((1U << mode->bitdepth) - 1U); /*highest possible value for this bit depth*/
+      size_t j = 0;
+      for(i = 0; i != numpixels; ++i, buffer += num_channels) {
+        unsigned value = readBitsFromReversedStream(&j, in, mode->bitdepth);
+        buffer[0] = buffer[1] = buffer[2] = (value * 255) / highest;
       }
     }
-    else
-    {
-      for(i = 0; i != numpixels; ++i, buffer += num_channels)
-      {
+  } else if(mode->colortype == LCT_RGB) {
+    if(mode->bitdepth == 8) {
+      lodepng_memcpy(buffer, in, numpixels * 3);
+    } else {
+      for(i = 0; i != numpixels; ++i, buffer += num_channels) {
+        buffer[0] = in[i * 6 + 0];
+        buffer[1] = in[i * 6 + 2];
+        buffer[2] = in[i * 6 + 4];
+      }
+    }
+  } else if(mode->colortype == LCT_PALETTE) {
+    if(mode->bitdepth == 8) {
+      for(i = 0; i != numpixels; ++i, buffer += num_channels) {
+        unsigned index = in[i];
+        /*out of bounds of palette not checked: see lodepng_color_mode_alloc_palette.*/
+        lodepng_memcpy(buffer, &mode->palette[index * 4], 3);
+      }
+    } else {
+      size_t j = 0;
+      for(i = 0; i != numpixels; ++i, buffer += num_channels) {
+        unsigned index = readBitsFromReversedStream(&j, in, mode->bitdepth);
+        /*out of bounds of palette not checked: see lodepng_color_mode_alloc_palette.*/
+        lodepng_memcpy(buffer, &mode->palette[index * 4], 3);
+      }
+    }
+  } else if(mode->colortype == LCT_GREY_ALPHA) {
+    if(mode->bitdepth == 8) {
+      for(i = 0; i != numpixels; ++i, buffer += num_channels) {
+        buffer[0] = buffer[1] = buffer[2] = in[i * 2 + 0];
+      }
+    } else {
+      for(i = 0; i != numpixels; ++i, buffer += num_channels) {
+        buffer[0] = buffer[1] = buffer[2] = in[i * 4 + 0];
+      }
+    }
+  } else if(mode->colortype == LCT_RGBA) {
+    if(mode->bitdepth == 8) {
+      for(i = 0; i != numpixels; ++i, buffer += num_channels) {
+        lodepng_memcpy(buffer, &in[i * 4], 3);
+      }
+    } else {
+      for(i = 0; i != numpixels; ++i, buffer += num_channels) {
         buffer[0] = in[i * 8 + 0];
         buffer[1] = in[i * 8 + 2];
         buffer[2] = in[i * 8 + 4];
-        if(has_alpha) buffer[3] = in[i * 8 + 6];
       }
     }
   }
@@ -3405,16 +3417,12 @@ static void getPixelColorsRGBA8(unsigned char* buffer, size_t numpixels,
 /*Get RGBA16 color of pixel with index i (y * width + x) from the raw image with
 given color type, but the given color type must be 16-bit itself.*/
 static void getPixelColorRGBA16(unsigned short* r, unsigned short* g, unsigned short* b, unsigned short* a,
-                                const unsigned char* in, size_t i, const LodePNGColorMode* mode)
-{
-  if(mode->colortype == LCT_GREY)
-  {
+                                const unsigned char* in, size_t i, const LodePNGColorMode* mode) {
+  if(mode->colortype == LCT_GREY) {
     *r = *g = *b = 256 * in[i * 2 + 0] + in[i * 2 + 1];
     if(mode->key_defined && 256U * in[i * 2 + 0] + in[i * 2 + 1] == mode->key_r) *a = 0;
     else *a = 65535;
-  }
-  else if(mode->colortype == LCT_RGB)
-  {
+  } else if(mode->colortype == LCT_RGB) {
     *r = 256u * in[i * 6 + 0] + in[i * 6 + 1];
     *g = 256u * in[i * 6 + 2] + in[i * 6 + 3];
     *b = 256u * in[i * 6 + 4] + in[i * 6 + 5];
@@ -3423,14 +3431,10 @@ static void getPixelColorRGBA16(unsigned short* r, unsigned short* g, unsigned s
        && 256u * in[i * 6 + 2] + in[i * 6 + 3] == mode->key_g
        && 256u * in[i * 6 + 4] + in[i * 6 + 5] == mode->key_b) *a = 0;
     else *a = 65535;
-  }
-  else if(mode->colortype == LCT_GREY_ALPHA)
-  {
+  } else if(mode->colortype == LCT_GREY_ALPHA) {
     *r = *g = *b = 256u * in[i * 4 + 0] + in[i * 4 + 1];
     *a = 256u * in[i * 4 + 2] + in[i * 4 + 3];
-  }
-  else if(mode->colortype == LCT_RGBA)
-  {
+  } else if(mode->colortype == LCT_RGBA) {
     *r = 256u * in[i * 8 + 0] + in[i * 8 + 1];
     *g = 256u * in[i * 8 + 2] + in[i * 8 + 3];
     *b = 256u * in[i * 8 + 4] + in[i * 8 + 5];
@@ -3440,91 +3444,146 @@ static void getPixelColorRGBA16(unsigned short* r, unsigned short* g, unsigned s
 
 unsigned lodepng_convert(unsigned char* out, const unsigned char* in,
                          const LodePNGColorMode* mode_out, const LodePNGColorMode* mode_in,
-                         unsigned w, unsigned h)
-{
+                         unsigned w, unsigned h) {
   size_t i;
   ColorTree tree;
-  size_t numpixels = w * h;
+  size_t numpixels = (size_t)w * (size_t)h;
+  unsigned error = 0;
 
-  if(lodepng_color_mode_equal(mode_out, mode_in))
-  {
+  if(lodepng_color_mode_equal(mode_out, mode_in)) {
     size_t numbytes = lodepng_get_raw_size(w, h, mode_in);
     for(i = 0; i != numbytes; ++i) out[i] = in[i];
     return 0;
   }
 
-  if(mode_out->colortype == LCT_PALETTE)
-  {
+  if(mode_out->colortype == LCT_PALETTE) {
     size_t palettesize = mode_out->palettesize;
     const unsigned char* palette = mode_out->palette;
-    size_t palsize = 1u << mode_out->bitdepth;
+    size_t palsize = (size_t)1u << mode_out->bitdepth;
     /*if the user specified output palette but did not give the values, assume
     they want the values of the input color type (assuming that one is palette).
     Note that we never create a new palette ourselves.*/
-    if(palettesize == 0)
-    {
+    if(palettesize == 0) {
       palettesize = mode_in->palettesize;
       palette = mode_in->palette;
+      /*if the input was also palette with same bitdepth, then the color types are also
+      equal, so copy literally. This to preserve the exact indices that were in the PNG
+      even in case there are duplicate colors in the palette.*/
+      if (mode_in->colortype == LCT_PALETTE && mode_in->bitdepth == mode_out->bitdepth) {
+        size_t numbytes = lodepng_get_raw_size(w, h, mode_in);
+        for(i = 0; i != numbytes; ++i) out[i] = in[i];
+        return 0;
+      }
     }
     if(palettesize < palsize) palsize = palettesize;
     color_tree_init(&tree);
-    for(i = 0; i != palsize; ++i)
-    {
+    for(i = 0; i != palsize; ++i) {
       const unsigned char* p = &palette[i * 4];
-      color_tree_add(&tree, p[0], p[1], p[2], p[3], i);
+      color_tree_add(&tree, p[0], p[1], p[2], p[3], (unsigned)i);
     }
   }
 
-  if(mode_in->bitdepth == 16 && mode_out->bitdepth == 16)
-  {
-    for(i = 0; i != numpixels; ++i)
-    {
+  if(mode_in->bitdepth == 16 && mode_out->bitdepth == 16) {
+    for(i = 0; i != numpixels; ++i) {
       unsigned short r = 0, g = 0, b = 0, a = 0;
       getPixelColorRGBA16(&r, &g, &b, &a, in, i, mode_in);
       rgba16ToPixel(out, i, mode_out, r, g, b, a);
     }
-  }
-  else if(mode_out->bitdepth == 8 && mode_out->colortype == LCT_RGBA)
-  {
-    getPixelColorsRGBA8(out, numpixels, 1, in, mode_in);
-  }
-  else if(mode_out->bitdepth == 8 && mode_out->colortype == LCT_RGB)
-  {
-    getPixelColorsRGBA8(out, numpixels, 0, in, mode_in);
-  }
-  else
-  {
+  } else if(mode_out->bitdepth == 8 && mode_out->colortype == LCT_RGBA) {
+    getPixelColorsRGBA8(out, numpixels, in, mode_in);
+  } else if(mode_out->bitdepth == 8 && mode_out->colortype == LCT_RGB) {
+    getPixelColorsRGB8(out, numpixels, in, mode_in);
+  } else {
     unsigned char r = 0, g = 0, b = 0, a = 0;
-    for(i = 0; i != numpixels; ++i)
-    {
+    for(i = 0; i != numpixels; ++i) {
       getPixelColorRGBA8(&r, &g, &b, &a, in, i, mode_in);
-      CERROR_TRY_RETURN(rgba8ToPixel(out, i, mode_out, &tree, r, g, b, a));
+      error = rgba8ToPixel(out, i, mode_out, &tree, r, g, b, a);
+      if (error) break;
     }
   }
 
-  if(mode_out->colortype == LCT_PALETTE)
-  {
+  if(mode_out->colortype == LCT_PALETTE) {
     color_tree_cleanup(&tree);
   }
 
-  return 0; /*no error*/
+  return error;
+}
+
+
+/* Converts a single rgb color without alpha from one type to another, color bits truncated to
+their bitdepth. In case of single channel (gray or palette), only the r channel is used. Slow
+function, do not use to process all pixels of an image. Alpha channel not supported on purpose:
+this is for bKGD, supporting alpha may prevent it from finding a color in the palette, from the
+specification it looks like bKGD should ignore the alpha values of the palette since it can use
+any palette index but doesn't have an alpha channel. Idem with ignoring color key. */
+unsigned lodepng_convert_rgb(
+    unsigned* r_out, unsigned* g_out, unsigned* b_out,
+    unsigned r_in, unsigned g_in, unsigned b_in,
+    const LodePNGColorMode* mode_out, const LodePNGColorMode* mode_in) {
+  unsigned r = 0, g = 0, b = 0;
+  unsigned mul = 65535 / ((1u << mode_in->bitdepth) - 1u); /*65535, 21845, 4369, 257, 1*/
+  unsigned shift = 16 - mode_out->bitdepth;
+
+  if(mode_in->colortype == LCT_GREY || mode_in->colortype == LCT_GREY_ALPHA) {
+    r = g = b = r_in * mul;
+  } else if(mode_in->colortype == LCT_RGB || mode_in->colortype == LCT_RGBA) {
+    r = r_in * mul;
+    g = g_in * mul;
+    b = b_in * mul;
+  } else if(mode_in->colortype == LCT_PALETTE) {
+    if(r_in >= mode_in->palettesize) return 82;
+    r = mode_in->palette[r_in * 4 + 0] * 257u;
+    g = mode_in->palette[r_in * 4 + 1] * 257u;
+    b = mode_in->palette[r_in * 4 + 2] * 257u;
+  } else {
+    return 31;
+  }
+
+  /* now convert to output format */
+  if(mode_out->colortype == LCT_GREY || mode_out->colortype == LCT_GREY_ALPHA) {
+    *r_out = r >> shift ;
+  } else if(mode_out->colortype == LCT_RGB || mode_out->colortype == LCT_RGBA) {
+    *r_out = r >> shift ;
+    *g_out = g >> shift ;
+    *b_out = b >> shift ;
+  } else if(mode_out->colortype == LCT_PALETTE) {
+    unsigned i;
+    /* a 16-bit color cannot be in the palette */
+    if((r >> 8) != (r & 255) || (g >> 8) != (g & 255) || (b >> 8) != (b & 255)) return 82;
+    for(i = 0; i < mode_out->palettesize; i++) {
+      unsigned j = i * 4;
+      if((r >> 8) == mode_out->palette[j + 0] && (g >> 8) == mode_out->palette[j + 1] &&
+          (b >> 8) == mode_out->palette[j + 2]) {
+        *r_out = i;
+        return 0;
+      }
+    }
+    return 82;
+  } else {
+    return 31;
+  }
+
+  return 0;
 }
 
 #ifdef LODEPNG_COMPILE_ENCODER
 
-void lodepng_color_profile_init(LodePNGColorProfile* profile)
-{
-  profile->colored = 0;
-  profile->key = 0;
-  profile->alpha = 0;
-  profile->key_r = profile->key_g = profile->key_b = 0;
-  profile->numcolors = 0;
-  profile->bits = 1;
+void lodepng_color_stats_init(LodePNGColorStats* stats) {
+  /*stats*/
+  stats->colored = 0;
+  stats->key = 0;
+  stats->key_r = stats->key_g = stats->key_b = 0;
+  stats->alpha = 0;
+  stats->numcolors = 0;
+  stats->bits = 1;
+  stats->numpixels = 0;
+  /*settings*/
+  stats->allow_palette = 1;
+  stats->allow_greyscale = 1;
 }
 
 /*function used for debug purposes with C++*/
-/*void printColorProfile(LodePNGColorProfile* p)
-{
+/*void printColorStats(LodePNGColorStats* p) {
   std::cout << "colored: " << (int)p->colored << ", ";
   std::cout << "key: " << (int)p->key << ", ";
   std::cout << "key_r: " << (int)p->key_r << ", ";
@@ -3536,237 +3595,246 @@ void lodepng_color_profile_init(LodePNGColorProfile* profile)
 }*/
 
 /*Returns how many bits needed to represent given value (max 8 bit)*/
-static unsigned getValueRequiredBits(unsigned char value)
-{
+static unsigned getValueRequiredBits(unsigned char value) {
   if(value == 0 || value == 255) return 1;
   /*The scaling of 2-bit and 4-bit values uses multiples of 85 and 17*/
   if(value % 17 == 0) return value % 85 == 0 ? 2 : 4;
   return 8;
 }
 
-/*profile must already have been inited with mode.
-It's ok to set some parameters of profile to done already.*/
-unsigned lodepng_get_color_profile(LodePNGColorProfile* profile,
-                                   const unsigned char* in, unsigned w, unsigned h,
-                                   const LodePNGColorMode* mode)
-{
-  unsigned error = 0;
+/*stats must already have been inited. */
+void lodepng_compute_color_stats(LodePNGColorStats* stats,
+                                 const unsigned char* in, unsigned w, unsigned h,
+                                 const LodePNGColorMode* mode_in) {
   size_t i;
   ColorTree tree;
-  size_t numpixels = w * h;
+  size_t numpixels = (size_t)w * (size_t)h;
 
-  unsigned colored_done = lodepng_is_greyscale_type(mode) ? 1 : 0;
-  unsigned alpha_done = lodepng_can_have_alpha(mode) ? 0 : 1;
+  /* mark things as done already if it would be impossible to have a more expensive case */
+  unsigned colored_done = lodepng_is_greyscale_type(mode_in) ? 1 : 0;
+  unsigned alpha_done = lodepng_can_have_alpha(mode_in) ? 0 : 1;
   unsigned numcolors_done = 0;
-  unsigned bpp = lodepng_get_bpp(mode);
-  unsigned bits_done = bpp == 1 ? 1 : 0;
+  unsigned bpp = lodepng_get_bpp(mode_in);
+  unsigned bits_done = (stats->bits == 1 && bpp == 1) ? 1 : 0;
+  unsigned sixteen = 0; /* whether the input image is 16 bit */
   unsigned maxnumcolors = 257;
-  unsigned sixteen = 0;
-  if(bpp <= 8) maxnumcolors = bpp == 1 ? 2 : (bpp == 2 ? 4 : (bpp == 4 ? 16 : 256));
+  if(bpp <= 8) maxnumcolors = LODEPNG_MIN(257, stats->numcolors + (1u << bpp));
+
+  stats->numpixels += numpixels;
+
+  /*if palette not allowed, no need to compute numcolors*/
+  if(!stats->allow_palette) numcolors_done = 1;
 
   color_tree_init(&tree);
 
+  /*If the stats was already filled in from previous data, fill its palette in tree
+  and mark things as done already if we know they are the most expensive case already*/
+  if(stats->alpha) alpha_done = 1;
+  if(stats->colored) colored_done = 1;
+  if(stats->bits == 16) numcolors_done = 1;
+  if(stats->bits >= bpp) bits_done = 1;
+  if(stats->numcolors >= maxnumcolors) numcolors_done = 1;
+
+  if(!numcolors_done) {
+    for(i = 0; i < stats->numcolors; i++) {
+      const unsigned char* color = &stats->palette[i * 4];
+      color_tree_add(&tree, color[0], color[1], color[2], color[3], i);
+    }
+  }
+
   /*Check if the 16-bit input is truly 16-bit*/
-  if(mode->bitdepth == 16)
-  {
+  if(mode_in->bitdepth == 16 && !sixteen) {
     unsigned short r, g, b, a;
-    for(i = 0; i != numpixels; ++i)
-    {
-      getPixelColorRGBA16(&r, &g, &b, &a, in, i, mode);
+    for(i = 0; i != numpixels; ++i) {
+      getPixelColorRGBA16(&r, &g, &b, &a, in, i, mode_in);
       if((r & 255) != ((r >> 8) & 255) || (g & 255) != ((g >> 8) & 255) ||
-         (b & 255) != ((b >> 8) & 255) || (a & 255) != ((a >> 8) & 255)) /*first and second byte differ*/
-      {
+         (b & 255) != ((b >> 8) & 255) || (a & 255) != ((a >> 8) & 255)) /*first and second byte differ*/ {
+        stats->bits = 16;
         sixteen = 1;
+        bits_done = 1;
+        numcolors_done = 1; /*counting colors no longer useful, palette doesn't support 16-bit*/
         break;
       }
     }
   }
 
-  if(sixteen)
-  {
+  if(sixteen) {
     unsigned short r = 0, g = 0, b = 0, a = 0;
-    profile->bits = 16;
-    bits_done = numcolors_done = 1; /*counting colors no longer useful, palette doesn't support 16-bit*/
 
-    for(i = 0; i != numpixels; ++i)
-    {
-      getPixelColorRGBA16(&r, &g, &b, &a, in, i, mode);
+    for(i = 0; i != numpixels; ++i) {
+      getPixelColorRGBA16(&r, &g, &b, &a, in, i, mode_in);
 
-      if(!colored_done && (r != g || r != b))
-      {
-        profile->colored = 1;
+      if(!colored_done && (r != g || r != b)) {
+        stats->colored = 1;
         colored_done = 1;
       }
 
-      if(!alpha_done)
-      {
-        unsigned matchkey = (r == profile->key_r && g == profile->key_g && b == profile->key_b);
-        if(a != 65535 && (a != 0 || (profile->key && !matchkey)))
-        {
-          profile->alpha = 1;
+      if(!alpha_done) {
+        unsigned matchkey = (r == stats->key_r && g == stats->key_g && b == stats->key_b);
+        if(a != 65535 && (a != 0 || (stats->key && !matchkey))) {
+          stats->alpha = 1;
+          stats->key = 0;
           alpha_done = 1;
-          if(profile->bits < 8) profile->bits = 8; /*PNG has no alphachannel modes with less than 8-bit per channel*/
-        }
-        else if(a == 0 && !profile->alpha && !profile->key)
-        {
-          profile->key = 1;
-          profile->key_r = r;
-          profile->key_g = g;
-          profile->key_b = b;
-        }
-        else if(a == 65535 && profile->key && matchkey)
-        {
+        } else if(a == 0 && !stats->alpha && !stats->key) {
+          stats->key = 1;
+          stats->key_r = r;
+          stats->key_g = g;
+          stats->key_b = b;
+        } else if(a == 65535 && stats->key && matchkey) {
           /* Color key cannot be used if an opaque pixel also has that RGB color. */
-          profile->alpha = 1;
+          stats->alpha = 1;
+          stats->key = 0;
           alpha_done = 1;
         }
       }
       if(alpha_done && numcolors_done && colored_done && bits_done) break;
     }
 
-    if(profile->key && !profile->alpha)
-    {
-      for(i = 0; i != numpixels; ++i)
-      {
-        getPixelColorRGBA16(&r, &g, &b, &a, in, i, mode);
-        if(a != 0 && r == profile->key_r && g == profile->key_g && b == profile->key_b)
-        {
+    if(stats->key && !stats->alpha) {
+      for(i = 0; i != numpixels; ++i) {
+        getPixelColorRGBA16(&r, &g, &b, &a, in, i, mode_in);
+        if(a != 0 && r == stats->key_r && g == stats->key_g && b == stats->key_b) {
           /* Color key cannot be used if an opaque pixel also has that RGB color. */
-          profile->alpha = 1;
+          stats->alpha = 1;
+          stats->key = 0;
           alpha_done = 1;
         }
       }
     }
-  }
-  else /* < 16-bit */
-  {
+  } else /* < 16-bit */ {
     unsigned char r = 0, g = 0, b = 0, a = 0;
-    for(i = 0; i != numpixels; ++i)
-    {
-      getPixelColorRGBA8(&r, &g, &b, &a, in, i, mode);
+    for(i = 0; i != numpixels; ++i) {
+      getPixelColorRGBA8(&r, &g, &b, &a, in, i, mode_in);
 
-      if(!bits_done && profile->bits < 8)
-      {
-        /*only r is checked, < 8 bits is only relevant for greyscale*/
+      if(!bits_done && stats->bits < 8) {
+        /*only r is checked, < 8 bits is only relevant for grayscale*/
         unsigned bits = getValueRequiredBits(r);
-        if(bits > profile->bits) profile->bits = bits;
+        if(bits > stats->bits) stats->bits = bits;
       }
-      bits_done = (profile->bits >= bpp);
+      bits_done = (stats->bits >= bpp);
 
-      if(!colored_done && (r != g || r != b))
-      {
-        profile->colored = 1;
+      if(!colored_done && (r != g || r != b)) {
+        stats->colored = 1;
         colored_done = 1;
-        if(profile->bits < 8) profile->bits = 8; /*PNG has no colored modes with less than 8-bit per channel*/
+        if(stats->bits < 8) stats->bits = 8; /*PNG has no colored modes with less than 8-bit per channel*/
       }
 
-      if(!alpha_done)
-      {
-        unsigned matchkey = (r == profile->key_r && g == profile->key_g && b == profile->key_b);
-        if(a != 255 && (a != 0 || (profile->key && !matchkey)))
-        {
-          profile->alpha = 1;
+      if(!alpha_done) {
+        unsigned matchkey = (r == stats->key_r && g == stats->key_g && b == stats->key_b);
+        if(a != 255 && (a != 0 || (stats->key && !matchkey))) {
+          stats->alpha = 1;
+          stats->key = 0;
           alpha_done = 1;
-          if(profile->bits < 8) profile->bits = 8; /*PNG has no alphachannel modes with less than 8-bit per channel*/
-        }
-        else if(a == 0 && !profile->alpha && !profile->key)
-        {
-          profile->key = 1;
-          profile->key_r = r;
-          profile->key_g = g;
-          profile->key_b = b;
-        }
-        else if(a == 255 && profile->key && matchkey)
-        {
+          if(stats->bits < 8) stats->bits = 8; /*PNG has no alphachannel modes with less than 8-bit per channel*/
+        } else if(a == 0 && !stats->alpha && !stats->key) {
+          stats->key = 1;
+          stats->key_r = r;
+          stats->key_g = g;
+          stats->key_b = b;
+        } else if(a == 255 && stats->key && matchkey) {
           /* Color key cannot be used if an opaque pixel also has that RGB color. */
-          profile->alpha = 1;
+          stats->alpha = 1;
+          stats->key = 0;
           alpha_done = 1;
-          if(profile->bits < 8) profile->bits = 8; /*PNG has no alphachannel modes with less than 8-bit per channel*/
+          if(stats->bits < 8) stats->bits = 8; /*PNG has no alphachannel modes with less than 8-bit per channel*/
         }
       }
 
-      if(!numcolors_done)
-      {
-        if(!color_tree_has(&tree, r, g, b, a))
-        {
-          color_tree_add(&tree, r, g, b, a, profile->numcolors);
-          if(profile->numcolors < 256)
-          {
-            unsigned char* p = profile->palette;
-            unsigned n = profile->numcolors;
+      if(!numcolors_done) {
+        if(!color_tree_has(&tree, r, g, b, a)) {
+          color_tree_add(&tree, r, g, b, a, stats->numcolors);
+          if(stats->numcolors < 256) {
+            unsigned char* p = stats->palette;
+            unsigned n = stats->numcolors;
             p[n * 4 + 0] = r;
             p[n * 4 + 1] = g;
             p[n * 4 + 2] = b;
             p[n * 4 + 3] = a;
           }
-          ++profile->numcolors;
-          numcolors_done = profile->numcolors >= maxnumcolors;
+          ++stats->numcolors;
+          numcolors_done = stats->numcolors >= maxnumcolors;
         }
       }
 
       if(alpha_done && numcolors_done && colored_done && bits_done) break;
     }
 
-    if(profile->key && !profile->alpha)
-    {
-      for(i = 0; i != numpixels; ++i)
-      {
-        getPixelColorRGBA8(&r, &g, &b, &a, in, i, mode);
-        if(a != 0 && r == profile->key_r && g == profile->key_g && b == profile->key_b)
-        {
+    if(stats->key && !stats->alpha) {
+      for(i = 0; i != numpixels; ++i) {
+        getPixelColorRGBA8(&r, &g, &b, &a, in, i, mode_in);
+        if(a != 0 && r == stats->key_r && g == stats->key_g && b == stats->key_b) {
           /* Color key cannot be used if an opaque pixel also has that RGB color. */
-          profile->alpha = 1;
+          stats->alpha = 1;
+          stats->key = 0;
           alpha_done = 1;
+          if(stats->bits < 8) stats->bits = 8; /*PNG has no alphachannel modes with less than 8-bit per channel*/
         }
       }
     }
 
-    /*make the profile's key always 16-bit for consistency - repeat each byte twice*/
-    profile->key_r += (profile->key_r << 8);
-    profile->key_g += (profile->key_g << 8);
-    profile->key_b += (profile->key_b << 8);
+    /*make the stats's key always 16-bit for consistency - repeat each byte twice*/
+    stats->key_r += (stats->key_r << 8);
+    stats->key_g += (stats->key_g << 8);
+    stats->key_b += (stats->key_b << 8);
   }
 
   color_tree_cleanup(&tree);
-  return error;
 }
 
-/*Automatically chooses color type that gives smallest amount of bits in the
-output image, e.g. grey if there are only greyscale pixels, palette if there
-are less than 256 colors, ...
-Updates values of mode with a potentially smaller color model. mode_out should
-contain the user chosen color model, but will be overwritten with the new chosen one.*/
-unsigned lodepng_auto_choose_color(LodePNGColorMode* mode_out,
-                                   const unsigned char* image, unsigned w, unsigned h,
-                                   const LodePNGColorMode* mode_in)
-{
-  LodePNGColorProfile prof;
+#ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS
+/*Adds a single color to the color stats. The stats must already have been inited. The color must be given as 16-bit
+(with 2 bytes repeating for 8-bit and 65535 for opaque alpha channel). This function is expensive, do not call it for
+all pixels of an image but only for a few additional values. */
+static void lodepng_color_stats_add(LodePNGColorStats* stats,
+                                    unsigned r, unsigned g, unsigned b, unsigned a) {
+  unsigned char image[8];
+  LodePNGColorMode mode;
+  lodepng_color_mode_init(&mode);
+  image[0] = r >> 8; image[1] = r; image[2] = g >> 8; image[3] = g;
+  image[4] = b >> 8; image[5] = b; image[6] = a >> 8; image[7] = a;
+  mode.bitdepth = 16;
+  mode.colortype = LCT_RGBA;
+  lodepng_compute_color_stats(stats, image, 1, 1, &mode);
+  lodepng_color_mode_cleanup(&mode);
+}
+#endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/
+
+unsigned auto_choose_color(LodePNGColorMode* mode_out,
+                           const LodePNGColorMode* mode_in,
+                           const LodePNGColorStats* stats) {
   unsigned error = 0;
-  unsigned i, n, palettebits, grey_ok, palette_ok;
+  unsigned palettebits;
+  size_t i, n;
+  size_t numpixels = stats->numpixels;
+  unsigned palette_ok, gray_ok;
+
+  unsigned alpha = stats->alpha;
+  unsigned key = stats->key;
+  unsigned bits = stats->bits;
 
-  lodepng_color_profile_init(&prof);
-  error = lodepng_get_color_profile(&prof, image, w, h, mode_in);
-  if(error) return error;
   mode_out->key_defined = 0;
 
-  if(prof.key && w * h <= 16)
-  {
-    prof.alpha = 1; /*too few pixels to justify tRNS chunk overhead*/
-    if(prof.bits < 8) prof.bits = 8; /*PNG has no alphachannel modes with less than 8-bit per channel*/
+  if(key && numpixels <= 16) {
+    alpha = 1; /*too few pixels to justify tRNS chunk overhead*/
+    key = 0;
+    if(bits < 8) bits = 8; /*PNG has no alphachannel modes with less than 8-bit per channel*/
   }
-  grey_ok = !prof.colored && !prof.alpha; /*grey without alpha, with potentially low bits*/
-  n = prof.numcolors;
+
+  gray_ok = !stats->colored;
+  if(!stats->allow_greyscale) gray_ok = 0;
+  if(!gray_ok && bits < 8) bits = 8;
+
+  n = stats->numcolors;
   palettebits = n <= 2 ? 1 : (n <= 4 ? 2 : (n <= 16 ? 4 : 8));
-  palette_ok = n <= 256 && (n * 2 < w * h) && prof.bits <= 8;
-  if(w * h < n * 2) palette_ok = 0; /*don't add palette overhead if image has only a few pixels*/
-  if(grey_ok && prof.bits <= palettebits) palette_ok = 0; /*grey is less overhead*/
+  palette_ok = n <= 256 && bits <= 8 && n != 0; /*n==0 means likely numcolors wasn't computed*/
+  if(numpixels < n * 2) palette_ok = 0; /*don't add palette overhead if image has only a few pixels*/
+  if(gray_ok && bits <= palettebits) palette_ok = 0; /*gray is less overhead*/
+  if(!stats->allow_palette) palette_ok = 0;
 
-  if(palette_ok)
-  {
-    unsigned char* p = prof.palette;
+  if(palette_ok) {
+    const unsigned char* p = stats->palette;
     lodepng_palette_clear(mode_out); /*remove potential earlier palette*/
-    for(i = 0; i != prof.numcolors; ++i)
-    {
+    for(i = 0; i != stats->numcolors; ++i) {
       error = lodepng_palette_add(mode_out, p[i * 4 + 0], p[i * 4 + 1], p[i * 4 + 2], p[i * 4 + 3]);
       if(error) break;
     }
@@ -3775,25 +3843,20 @@ unsigned lodepng_auto_choose_color(LodePNGColorMode* mode_out,
     mode_out->bitdepth = palettebits;
 
     if(mode_in->colortype == LCT_PALETTE && mode_in->palettesize >= mode_out->palettesize
-        && mode_in->bitdepth == mode_out->bitdepth)
-    {
+        && mode_in->bitdepth == mode_out->bitdepth) {
       /*If input should have same palette colors, keep original to preserve its order and prevent conversion*/
       lodepng_color_mode_cleanup(mode_out);
       lodepng_color_mode_copy(mode_out, mode_in);
     }
-  }
-  else /*8-bit or 16-bit per channel*/
-  {
-    mode_out->bitdepth = prof.bits;
-    mode_out->colortype = prof.alpha ? (prof.colored ? LCT_RGBA : LCT_GREY_ALPHA)
-                                     : (prof.colored ? LCT_RGB : LCT_GREY);
-
-    if(prof.key && !prof.alpha)
-    {
-      unsigned mask = (1u << mode_out->bitdepth) - 1u; /*profile always uses 16-bit, mask converts it*/
-      mode_out->key_r = prof.key_r & mask;
-      mode_out->key_g = prof.key_g & mask;
-      mode_out->key_b = prof.key_b & mask;
+  } else /*8-bit or 16-bit per channel*/ {
+    mode_out->bitdepth = bits;
+    mode_out->colortype = alpha ? (gray_ok ? LCT_GREY_ALPHA : LCT_RGBA)
+                                : (gray_ok ? LCT_GREY : LCT_RGB);
+    if(key) {
+      unsigned mask = (1u << mode_out->bitdepth) - 1u; /*stats always uses 16-bit, mask converts it*/
+      mode_out->key_r = stats->key_r & mask;
+      mode_out->key_g = stats->key_g & mask;
+      mode_out->key_b = stats->key_b & mask;
       mode_out->key_defined = 1;
     }
   }
@@ -3804,19 +3867,17 @@ unsigned lodepng_auto_choose_color(LodePNGColorMode* mode_out,
 #endif /* #ifdef LODEPNG_COMPILE_ENCODER */
 
 /*
-Paeth predicter, used by PNG filter type 4
+Paeth predictor, used by PNG filter type 4
 The parameters are of type short, but should come from unsigned chars, the shorts
 are only needed to make the paeth calculation correct.
 */
-static unsigned char paethPredictor(short a, short b, short c)
-{
-  short pa = abs(b - c);
-  short pb = abs(a - c);
-  short pc = abs(a + b - c - c);
-
-  if(pc < pa && pc < pb) return (unsigned char)c;
-  else if(pb < pa) return (unsigned char)b;
-  else return (unsigned char)a;
+static unsigned char paethPredictor(short a, short b, short c) {
+  short pa = LODEPNG_ABS(b - c);
+  short pb = LODEPNG_ABS(a - c);
+  short pc = LODEPNG_ABS(a + b - c - c);
+  /* return input value associated with smallest of pa, pb, pc (with certain priority if equal) */
+  if(pb < pa) { a = b; pa = pb; }
+  return (pc < pa) ? c : a;
 }
 
 /*shared values used by multiple Adam7 related functions*/
@@ -3842,14 +3903,12 @@ bpp: bits per pixel
  end at a full byte
 */
 static void Adam7_getpassvalues(unsigned passw[7], unsigned passh[7], size_t filter_passstart[8],
-                                size_t padded_passstart[8], size_t passstart[8], unsigned w, unsigned h, unsigned bpp)
-{
+                                size_t padded_passstart[8], size_t passstart[8], unsigned w, unsigned h, unsigned bpp) {
   /*the passstart values have 8 values: the 8th one indicates the byte after the end of the 7th (= last) pass*/
   unsigned i;
 
   /*calculate width and height in pixels of each pass*/
-  for(i = 0; i != 7; ++i)
-  {
+  for(i = 0; i != 7; ++i) {
     passw[i] = (w + ADAM7_DX[i] - ADAM7_IX[i] - 1) / ADAM7_DX[i];
     passh[i] = (h + ADAM7_DY[i] - ADAM7_IY[i] - 1) / ADAM7_DY[i];
     if(passw[i] == 0) passh[i] = 0;
@@ -3857,15 +3916,14 @@ static void Adam7_getpassvalues(unsigned passw[7], unsigned passh[7], size_t fil
   }
 
   filter_passstart[0] = padded_passstart[0] = passstart[0] = 0;
-  for(i = 0; i != 7; ++i)
-  {
+  for(i = 0; i != 7; ++i) {
     /*if passw[i] is 0, it's 0 bytes, not 1 (no filtertype-byte)*/
     filter_passstart[i + 1] = filter_passstart[i]
-                            + ((passw[i] && passh[i]) ? passh[i] * (1 + (passw[i] * bpp + 7) / 8) : 0);
+                            + ((passw[i] && passh[i]) ? passh[i] * (1u + (passw[i] * bpp + 7u) / 8u) : 0);
     /*bits padded if needed to fill full byte at end of each scanline*/
-    padded_passstart[i + 1] = padded_passstart[i] + passh[i] * ((passw[i] * bpp + 7) / 8);
+    padded_passstart[i + 1] = padded_passstart[i] + passh[i] * ((passw[i] * bpp + 7u) / 8u);
     /*only padded at end of reduced image*/
-    passstart[i + 1] = passstart[i] + (passh[i] * passw[i] * bpp + 7) / 8;
+    passstart[i + 1] = passstart[i] + (passh[i] * passw[i] * bpp + 7u) / 8u;
   }
 }
 
@@ -3877,60 +3935,51 @@ static void Adam7_getpassvalues(unsigned passw[7], unsigned passh[7], size_t fil
 
 /*read the information from the header and store it in the LodePNGInfo. return value is error*/
 unsigned lodepng_inspect(unsigned* w, unsigned* h, LodePNGState* state,
-                         const unsigned char* in, size_t insize)
-{
+                         const unsigned char* in, size_t insize) {
+  unsigned width, height;
   LodePNGInfo* info = &state->info_png;
-  if(insize == 0 || in == 0)
-  {
+  if(insize == 0 || in == 0) {
     CERROR_RETURN_ERROR(state->error, 48); /*error: the given data is empty*/
   }
-  if(insize < 33)
-  {
+  if(insize < 33) {
     CERROR_RETURN_ERROR(state->error, 27); /*error: the data length is smaller than the length of a PNG header*/
   }
 
   /*when decoding a new PNG image, make sure all parameters created after previous decoding are reset*/
+  /* TODO: remove this. One should use a new LodePNGState for new sessions */
   lodepng_info_cleanup(info);
   lodepng_info_init(info);
 
   if(in[0] != 137 || in[1] != 80 || in[2] != 78 || in[3] != 71
-     || in[4] != 13 || in[5] != 10 || in[6] != 26 || in[7] != 10)
-  {
+     || in[4] != 13 || in[5] != 10 || in[6] != 26 || in[7] != 10) {
     CERROR_RETURN_ERROR(state->error, 28); /*error: the first 8 bytes are not the correct PNG signature*/
   }
-  if(lodepng_chunk_length(in + 8) != 13)
-  {
+  if(lodepng_chunk_length(in + 8) != 13) {
     CERROR_RETURN_ERROR(state->error, 94); /*error: header size must be 13 bytes*/
   }
-  if(!lodepng_chunk_type_equals(in + 8, "IHDR"))
-  {
+  if(!lodepng_chunk_type_equals(in + 8, "IHDR")) {
     CERROR_RETURN_ERROR(state->error, 29); /*error: it doesn't start with a IHDR chunk!*/
   }
 
   /*read the values given in the header*/
-  *w = lodepng_read32bitInt(&in[16]);
-  *h = lodepng_read32bitInt(&in[20]);
+  width = lodepng_read32bitInt(&in[16]);
+  height = lodepng_read32bitInt(&in[20]);
+  /*TODO: remove the undocumented feature that allows to give null pointers to width or height*/
+  if(w) *w = width;
+  if(h) *h = height;
   info->color.bitdepth = in[24];
   info->color.colortype = (LodePNGColorType)in[25];
   info->compression_method = in[26];
   info->filter_method = in[27];
   info->interlace_method = in[28];
 
-  if(*w == 0 || *h == 0)
-  {
-    CERROR_RETURN_ERROR(state->error, 93);
-  }
-
-  if(!state->decoder.ignore_crc)
-  {
-    unsigned CRC = lodepng_read32bitInt(&in[29]);
-    unsigned checksum = lodepng_crc32(&in[12], 17);
-    if(CRC != checksum)
-    {
-      CERROR_RETURN_ERROR(state->error, 57); /*invalid CRC*/
-    }
-  }
+  /*errors returned only after the parsing so other values are still output*/
 
+  /*error: invalid image size*/
+  if(width == 0 || height == 0) CERROR_RETURN_ERROR(state->error, 93);
+  /*error: invalid colortype or bitdepth combination*/
+  state->error = checkColorValidity(info->color.colortype, info->color.bitdepth);
+  if(state->error) return state->error;
   /*error: only compression method 0 is allowed in the specification*/
   if(info->compression_method != 0) CERROR_RETURN_ERROR(state->error, 32);
   /*error: only filter method 0 is allowed in the specification*/
@@ -3938,13 +3987,19 @@ unsigned lodepng_inspect(unsigned* w, unsigned* h, LodePNGState* state,
   /*error: only interlace methods 0 and 1 exist in the specification*/
   if(info->interlace_method > 1) CERROR_RETURN_ERROR(state->error, 34);
 
-  state->error = checkColorValidity(info->color.colortype, info->color.bitdepth);
+  if(!state->decoder.ignore_crc) {
+    unsigned CRC = lodepng_read32bitInt(&in[29]);
+    unsigned checksum = lodepng_crc32(&in[12], 17);
+    if(CRC != checksum) {
+      CERROR_RETURN_ERROR(state->error, 57); /*invalid CRC*/
+    }
+  }
+
   return state->error;
 }
 
 static unsigned unfilterScanline(unsigned char* recon, const unsigned char* scanline, const unsigned char* precon,
-                                 size_t bytewidth, unsigned char filterType, size_t length)
-{
+                                 size_t bytewidth, unsigned char filterType, size_t length) {
   /*
   For PNG filter method 0
   unfilter a PNG image scanline by scanline. when the pixels are smaller than 1 byte,
@@ -3955,8 +4010,7 @@ static unsigned unfilterScanline(unsigned char* recon, const unsigned char* scan
   */
 
   size_t i;
-  switch(filterType)
-  {
+  switch(filterType) {
     case 0:
       for(i = 0; i != length; ++i) recon[i] = scanline[i];
       break;
@@ -3965,59 +4019,83 @@ static unsigned unfilterScanline(unsigned char* recon, const unsigned char* scan
       for(i = bytewidth; i < length; ++i) recon[i] = scanline[i] + recon[i - bytewidth];
       break;
     case 2:
-      if(precon)
-      {
+      if(precon) {
         for(i = 0; i != length; ++i) recon[i] = scanline[i] + precon[i];
-      }
-      else
-      {
+      } else {
         for(i = 0; i != length; ++i) recon[i] = scanline[i];
       }
       break;
     case 3:
-      if(precon)
-      {
-        for(i = 0; i != bytewidth; ++i) recon[i] = scanline[i] + (precon[i] >> 1);
-        for(i = bytewidth; i < length; ++i) recon[i] = scanline[i] + ((recon[i - bytewidth] + precon[i]) >> 1);
-      }
-      else
-      {
+      if(precon) {
+        for(i = 0; i != bytewidth; ++i) recon[i] = scanline[i] + (precon[i] >> 1u);
+        for(i = bytewidth; i < length; ++i) recon[i] = scanline[i] + ((recon[i - bytewidth] + precon[i]) >> 1u);
+      } else {
         for(i = 0; i != bytewidth; ++i) recon[i] = scanline[i];
-        for(i = bytewidth; i < length; ++i) recon[i] = scanline[i] + (recon[i - bytewidth] >> 1);
+        for(i = bytewidth; i < length; ++i) recon[i] = scanline[i] + (recon[i - bytewidth] >> 1u);
       }
       break;
     case 4:
-      if(precon)
-      {
-        for(i = 0; i != bytewidth; ++i)
-        {
+      if(precon) {
+        for(i = 0; i != bytewidth; ++i) {
           recon[i] = (scanline[i] + precon[i]); /*paethPredictor(0, precon[i], 0) is always precon[i]*/
         }
-        for(i = bytewidth; i < length; ++i)
-        {
+
+        /* Unroll independent paths of the paeth predictor. A 6x and 8x version would also be possible but that
+        adds too much code. Whether this actually speeds anything up at all depends on compiler and settings. */
+        if(bytewidth >= 4) {
+          for(; i + 3 < length; i += 4) {
+            size_t j = i - bytewidth;
+            unsigned char s0 = scanline[i + 0], s1 = scanline[i + 1], s2 = scanline[i + 2], s3 = scanline[i + 3];
+            unsigned char r0 = recon[j + 0], r1 = recon[j + 1], r2 = recon[j + 2], r3 = recon[j + 3];
+            unsigned char p0 = precon[i + 0], p1 = precon[i + 1], p2 = precon[i + 2], p3 = precon[i + 3];
+            unsigned char q0 = precon[j + 0], q1 = precon[j + 1], q2 = precon[j + 2], q3 = precon[j + 3];
+            recon[i + 0] = s0 + paethPredictor(r0, p0, q0);
+            recon[i + 1] = s1 + paethPredictor(r1, p1, q1);
+            recon[i + 2] = s2 + paethPredictor(r2, p2, q2);
+            recon[i + 3] = s3 + paethPredictor(r3, p3, q3);
+          }
+        } else if(bytewidth >= 3) {
+          for(; i + 2 < length; i += 3) {
+            size_t j = i - bytewidth;
+            unsigned char s0 = scanline[i + 0], s1 = scanline[i + 1], s2 = scanline[i + 2];
+            unsigned char r0 = recon[j + 0], r1 = recon[j + 1], r2 = recon[j + 2];
+            unsigned char p0 = precon[i + 0], p1 = precon[i + 1], p2 = precon[i + 2];
+            unsigned char q0 = precon[j + 0], q1 = precon[j + 1], q2 = precon[j + 2];
+            recon[i + 0] = s0 + paethPredictor(r0, p0, q0);
+            recon[i + 1] = s1 + paethPredictor(r1, p1, q1);
+            recon[i + 2] = s2 + paethPredictor(r2, p2, q2);
+          }
+        } else if(bytewidth >= 2) {
+          for(; i + 1 < length; i += 2) {
+            size_t j = i - bytewidth;
+            unsigned char s0 = scanline[i + 0], s1 = scanline[i + 1];
+            unsigned char r0 = recon[j + 0], r1 = recon[j + 1];
+            unsigned char p0 = precon[i + 0], p1 = precon[i + 1];
+            unsigned char q0 = precon[j + 0], q1 = precon[j + 1];
+            recon[i + 0] = s0 + paethPredictor(r0, p0, q0);
+            recon[i + 1] = s1 + paethPredictor(r1, p1, q1);
+          }
+        }
+
+        for(; i != length; ++i) {
           recon[i] = (scanline[i] + paethPredictor(recon[i - bytewidth], precon[i], precon[i - bytewidth]));
         }
-      }
-      else
-      {
-        for(i = 0; i != bytewidth; ++i)
-        {
+      } else {
+        for(i = 0; i != bytewidth; ++i) {
           recon[i] = scanline[i];
         }
-        for(i = bytewidth; i < length; ++i)
-        {
+        for(i = bytewidth; i < length; ++i) {
           /*paethPredictor(recon[i - bytewidth], 0, 0) is always recon[i - bytewidth]*/
           recon[i] = (scanline[i] + recon[i - bytewidth]);
         }
       }
       break;
-    default: return 36; /*error: unexisting filter type given*/
+    default: return 36; /*error: nonexistent filter type given*/
   }
   return 0;
 }
 
-static unsigned unfilter(unsigned char* out, const unsigned char* in, unsigned w, unsigned h, unsigned bpp)
-{
+static unsigned unfilter(unsigned char* out, const unsigned char* in, unsigned w, unsigned h, unsigned bpp) {
   /*
   For PNG filter method 0
   this function unfilters a single image (e.g. without interlacing this is called once, with Adam7 seven times)
@@ -4030,11 +4108,10 @@ static unsigned unfilter(unsigned char* out, const unsigned char* in, unsigned w
   unsigned char* prevline = 0;
 
   /*bytewidth is used for filtering, is 1 when bpp < 8, number of bytes per pixel otherwise*/
-  size_t bytewidth = (bpp + 7) / 8;
-  size_t linebytes = (w * bpp + 7) / 8;
+  size_t bytewidth = (bpp + 7u) / 8u;
+  size_t linebytes = (w * bpp + 7u) / 8u;
 
-  for(y = 0; y < h; ++y)
-  {
+  for(y = 0; y < h; ++y) {
     size_t outindex = linebytes * y;
     size_t inindex = (1 + linebytes) * y; /*the extra filterbyte added to each row*/
     unsigned char filterType = in[inindex];
@@ -4058,50 +4135,39 @@ out must be big enough AND must be 0 everywhere if bpp < 8 in the current implem
 (because that's likely a little bit faster)
 NOTE: comments about padding bits are only relevant if bpp < 8
 */
-static void Adam7_deinterlace(unsigned char* out, const unsigned char* in, unsigned w, unsigned h, unsigned bpp)
-{
+static void Adam7_deinterlace(unsigned char* out, const unsigned char* in, unsigned w, unsigned h, unsigned bpp) {
   unsigned passw[7], passh[7];
   size_t filter_passstart[8], padded_passstart[8], passstart[8];
   unsigned i;
 
   Adam7_getpassvalues(passw, passh, filter_passstart, padded_passstart, passstart, w, h, bpp);
 
-  if(bpp >= 8)
-  {
-    for(i = 0; i != 7; ++i)
-    {
+  if(bpp >= 8) {
+    for(i = 0; i != 7; ++i) {
       unsigned x, y, b;
-      size_t bytewidth = bpp / 8;
+      size_t bytewidth = bpp / 8u;
       for(y = 0; y < passh[i]; ++y)
-      for(x = 0; x < passw[i]; ++x)
-      {
+      for(x = 0; x < passw[i]; ++x) {
         size_t pixelinstart = passstart[i] + (y * passw[i] + x) * bytewidth;
         size_t pixeloutstart = ((ADAM7_IY[i] + y * ADAM7_DY[i]) * w + ADAM7_IX[i] + x * ADAM7_DX[i]) * bytewidth;
-        for(b = 0; b < bytewidth; ++b)
-        {
+        for(b = 0; b < bytewidth; ++b) {
           out[pixeloutstart + b] = in[pixelinstart + b];
         }
       }
     }
-  }
-  else /*bpp < 8: Adam7 with pixels < 8 bit is a bit trickier: with bit pointers*/
-  {
-    for(i = 0; i != 7; ++i)
-    {
+  } else /*bpp < 8: Adam7 with pixels < 8 bit is a bit trickier: with bit pointers*/ {
+    for(i = 0; i != 7; ++i) {
       unsigned x, y, b;
       unsigned ilinebits = bpp * passw[i];
       unsigned olinebits = bpp * w;
       size_t obp, ibp; /*bit pointers (for out and in buffer)*/
       for(y = 0; y < passh[i]; ++y)
-      for(x = 0; x < passw[i]; ++x)
-      {
+      for(x = 0; x < passw[i]; ++x) {
         ibp = (8 * passstart[i]) + (y * ilinebits + x * bpp);
         obp = (ADAM7_IY[i] + y * ADAM7_DY[i]) * olinebits + (ADAM7_IX[i] + x * ADAM7_DX[i]) * bpp;
-        for(b = 0; b < bpp; ++b)
-        {
+        for(b = 0; b < bpp; ++b) {
           unsigned char bit = readBitFromReversedStream(&ibp, in);
-          /*note that this function assumes the out buffer is completely 0, use setBitOfReversedStream otherwise*/
-          setBitOfReversedStream0(&obp, out, bit);
+          setBitOfReversedStream(&obp, out, bit);
         }
       }
     }
@@ -4109,8 +4175,7 @@ static void Adam7_deinterlace(unsigned char* out, const unsigned char* in, unsig
 }
 
 static void removePaddingBits(unsigned char* out, const unsigned char* in,
-                              size_t olinebits, size_t ilinebits, unsigned h)
-{
+                              size_t olinebits, size_t ilinebits, unsigned h) {
   /*
   After filtering there are still padding bits if scanlines have non multiple of 8 bit amounts. They need
   to be removed (except at last scanline of (Adam7-reduced) image) before working with pure image buffers
@@ -4123,11 +4188,9 @@ static void removePaddingBits(unsigned char* out, const unsigned char* in,
   unsigned y;
   size_t diff = ilinebits - olinebits;
   size_t ibp = 0, obp = 0; /*input and output bit pointers*/
-  for(y = 0; y < h; ++y)
-  {
+  for(y = 0; y < h; ++y) {
     size_t x;
-    for(x = 0; x < olinebits; ++x)
-    {
+    for(x = 0; x < olinebits; ++x) {
       unsigned char bit = readBitFromReversedStream(&ibp, in);
       setBitOfReversedStream(&obp, out, bit);
     }
@@ -4139,46 +4202,39 @@ static void removePaddingBits(unsigned char* out, const unsigned char* in,
 the IDAT chunks (with filter index bytes and possible padding bits)
 return value is error*/
 static unsigned postProcessScanlines(unsigned char* out, unsigned char* in,
-                                     unsigned w, unsigned h, const LodePNGInfo* info_png)
-{
+                                     unsigned w, unsigned h, const LodePNGInfo* info_png) {
   /*
   This function converts the filtered-padded-interlaced data into pure 2D image buffer with the PNG's colortype.
   Steps:
-  *) if no Adam7: 1) unfilter 2) remove padding bits (= posible extra bits per scanline if bpp < 8)
+  *) if no Adam7: 1) unfilter 2) remove padding bits (= possible extra bits per scanline if bpp < 8)
   *) if adam7: 1) 7x unfilter 2) 7x remove padding bits 3) Adam7_deinterlace
   NOTE: the in buffer will be overwritten with intermediate data!
   */
   unsigned bpp = lodepng_get_bpp(&info_png->color);
   if(bpp == 0) return 31; /*error: invalid colortype*/
 
-  if(info_png->interlace_method == 0)
-  {
-    if(bpp < 8 && w * bpp != ((w * bpp + 7) / 8) * 8)
-    {
+  if(info_png->interlace_method == 0) {
+    if(bpp < 8 && w * bpp != ((w * bpp + 7u) / 8u) * 8u) {
       CERROR_TRY_RETURN(unfilter(in, in, w, h, bpp));
-      removePaddingBits(out, in, w * bpp, ((w * bpp + 7) / 8) * 8, h);
+      removePaddingBits(out, in, w * bpp, ((w * bpp + 7u) / 8u) * 8u, h);
     }
     /*we can immediately filter into the out buffer, no other steps needed*/
     else CERROR_TRY_RETURN(unfilter(out, in, w, h, bpp));
-  }
-  else /*interlace_method is 1 (Adam7)*/
-  {
+  } else /*interlace_method is 1 (Adam7)*/ {
     unsigned passw[7], passh[7]; size_t filter_passstart[8], padded_passstart[8], passstart[8];
     unsigned i;
 
     Adam7_getpassvalues(passw, passh, filter_passstart, padded_passstart, passstart, w, h, bpp);
 
-    for(i = 0; i != 7; ++i)
-    {
+    for(i = 0; i != 7; ++i) {
       CERROR_TRY_RETURN(unfilter(&in[padded_passstart[i]], &in[filter_passstart[i]], passw[i], passh[i], bpp));
       /*TODO: possible efficiency improvement: if in this reduced image the bits fit nicely in 1 scanline,
       move bytes instead of bits or move not at all*/
-      if(bpp < 8)
-      {
+      if(bpp < 8) {
         /*remove padding bits in scanlines; after this there still may be padding
         bits between the different reduced images: each reduced image still starts nicely at a byte*/
         removePaddingBits(&in[passstart[i]], &in[padded_passstart[i]], passw[i] * bpp,
-                          ((passw[i] * bpp + 7) / 8) * 8, passh[i]);
+                          ((passw[i] * bpp + 7u) / 8u) * 8u, passh[i]);
       }
     }
 
@@ -4188,21 +4244,17 @@ static unsigned postProcessScanlines(unsigned char* out, unsigned char* in,
   return 0;
 }
 
-static unsigned readChunk_PLTE(LodePNGColorMode* color, const unsigned char* data, size_t chunkLength)
-{
+static unsigned readChunk_PLTE(LodePNGColorMode* color, const unsigned char* data, size_t chunkLength) {
   unsigned pos = 0, i;
-  if(color->palette) lodepng_free(color->palette);
-  color->palettesize = chunkLength / 3;
-  color->palette = (unsigned char*)lodepng_malloc(4 * color->palettesize);
-  if(!color->palette && color->palettesize)
-  {
+  color->palettesize = chunkLength / 3u;
+  if(color->palettesize == 0 || color->palettesize > 256) return 38; /*error: palette too small or big*/
+  lodepng_color_mode_alloc_palette(color);
+  if(!color->palette && color->palettesize) {
     color->palettesize = 0;
     return 83; /*alloc fail*/
   }
-  if(color->palettesize > 256) return 38; /*error: palette too big*/
 
-  for(i = 0; i != color->palettesize; ++i)
-  {
+  for(i = 0; i != color->palettesize; ++i) {
     color->palette[4 * i + 0] = data[pos++]; /*R*/
     color->palette[4 * i + 1] = data[pos++]; /*G*/
     color->palette[4 * i + 2] = data[pos++]; /*B*/
@@ -4212,26 +4264,20 @@ static unsigned readChunk_PLTE(LodePNGColorMode* color, const unsigned char* dat
   return 0; /* OK */
 }
 
-static unsigned readChunk_tRNS(LodePNGColorMode* color, const unsigned char* data, size_t chunkLength)
-{
+static unsigned readChunk_tRNS(LodePNGColorMode* color, const unsigned char* data, size_t chunkLength) {
   unsigned i;
-  if(color->colortype == LCT_PALETTE)
-  {
+  if(color->colortype == LCT_PALETTE) {
     /*error: more alpha values given than there are palette entries*/
-    if(chunkLength > color->palettesize) return 38;
+    if(chunkLength > color->palettesize) return 39;
 
     for(i = 0; i != chunkLength; ++i) color->palette[4 * i + 3] = data[i];
-  }
-  else if(color->colortype == LCT_GREY)
-  {
-    /*error: this chunk must be 2 bytes for greyscale image*/
+  } else if(color->colortype == LCT_GREY) {
+    /*error: this chunk must be 2 bytes for grayscale image*/
     if(chunkLength != 2) return 30;
 
     color->key_defined = 1;
     color->key_r = color->key_g = color->key_b = 256u * data[0] + data[1];
-  }
-  else if(color->colortype == LCT_RGB)
-  {
+  } else if(color->colortype == LCT_RGB) {
     /*error: this chunk must be 6 bytes for RGB image*/
     if(chunkLength != 6) return 41;
 
@@ -4248,29 +4294,28 @@ static unsigned readChunk_tRNS(LodePNGColorMode* color, const unsigned char* dat
 
 #ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS
 /*background color chunk (bKGD)*/
-static unsigned readChunk_bKGD(LodePNGInfo* info, const unsigned char* data, size_t chunkLength)
-{
-  if(info->color.colortype == LCT_PALETTE)
-  {
+static unsigned readChunk_bKGD(LodePNGInfo* info, const unsigned char* data, size_t chunkLength) {
+  if(info->color.colortype == LCT_PALETTE) {
     /*error: this chunk must be 1 byte for indexed color image*/
     if(chunkLength != 1) return 43;
 
+    /*error: invalid palette index, or maybe this chunk appeared before PLTE*/
+    if(data[0] >= info->color.palettesize) return 103;
+
     info->background_defined = 1;
     info->background_r = info->background_g = info->background_b = data[0];
-  }
-  else if(info->color.colortype == LCT_GREY || info->color.colortype == LCT_GREY_ALPHA)
-  {
-    /*error: this chunk must be 2 bytes for greyscale image*/
+  } else if(info->color.colortype == LCT_GREY || info->color.colortype == LCT_GREY_ALPHA) {
+    /*error: this chunk must be 2 bytes for grayscale image*/
     if(chunkLength != 2) return 44;
 
+    /*the values are truncated to bitdepth in the PNG file*/
     info->background_defined = 1;
     info->background_r = info->background_g = info->background_b = 256u * data[0] + data[1];
-  }
-  else if(info->color.colortype == LCT_RGB || info->color.colortype == LCT_RGBA)
-  {
-    /*error: this chunk must be 6 bytes for greyscale image*/
+  } else if(info->color.colortype == LCT_RGB || info->color.colortype == LCT_RGBA) {
+    /*error: this chunk must be 6 bytes for grayscale image*/
     if(chunkLength != 6) return 45;
 
+    /*the values are truncated to bitdepth in the PNG file*/
     info->background_defined = 1;
     info->background_r = 256u * data[0] + data[1];
     info->background_g = 256u * data[2] + data[3];
@@ -4281,14 +4326,12 @@ static unsigned readChunk_bKGD(LodePNGInfo* info, const unsigned char* data, siz
 }
 
 /*text chunk (tEXt)*/
-static unsigned readChunk_tEXt(LodePNGInfo* info, const unsigned char* data, size_t chunkLength)
-{
+static unsigned readChunk_tEXt(LodePNGInfo* info, const unsigned char* data, size_t chunkLength) {
   unsigned error = 0;
   char *key = 0, *str = 0;
   unsigned i;
 
-  while(!error) /*not really a while loop, only used to break on error*/
-  {
+  while(!error) /*not really a while loop, only used to break on error*/ {
     unsigned length, string2_begin;
 
     length = 0;
@@ -4305,7 +4348,7 @@ static unsigned readChunk_tEXt(LodePNGInfo* info, const unsigned char* data, siz
 
     string2_begin = length + 1; /*skip keyword null terminator*/
 
-    length = chunkLength < string2_begin ? 0 : chunkLength - string2_begin;
+    length = (unsigned)(chunkLength < string2_begin ? 0 : chunkLength - string2_begin);
     str = (char*)lodepng_malloc(length + 1);
     if(!str) CERROR_BREAK(error, 83); /*alloc fail*/
 
@@ -4325,8 +4368,7 @@ static unsigned readChunk_tEXt(LodePNGInfo* info, const unsigned char* data, siz
 
 /*compressed text chunk (zTXt)*/
 static unsigned readChunk_zTXt(LodePNGInfo* info, const LodePNGDecompressSettings* zlibsettings,
-                               const unsigned char* data, size_t chunkLength)
-{
+                               const unsigned char* data, size_t chunkLength) {
   unsigned error = 0;
   unsigned i;
 
@@ -4336,8 +4378,7 @@ static unsigned readChunk_zTXt(LodePNGInfo* info, const LodePNGDecompressSetting
 
   ucvector_init(&decoded);
 
-  while(!error) /*not really a while loop, only used to break on error*/
-  {
+  while(!error) /*not really a while loop, only used to break on error*/ {
     for(length = 0; length < chunkLength && data[length] != 0; ++length) ;
     if(length + 2 >= chunkLength) CERROR_BREAK(error, 75); /*no null termination, corrupt?*/
     if(length < 1 || length > 79) CERROR_BREAK(error, 89); /*keyword too short or long*/
@@ -4353,10 +4394,10 @@ static unsigned readChunk_zTXt(LodePNGInfo* info, const LodePNGDecompressSetting
     string2_begin = length + 2;
     if(string2_begin > chunkLength) CERROR_BREAK(error, 75); /*no null termination, corrupt?*/
 
-    length = chunkLength - string2_begin;
+    length = (unsigned)chunkLength - string2_begin;
     /*will fail if zlib error, e.g. if length is too small*/
     error = zlib_decompress(&decoded.data, &decoded.size,
-                            (unsigned char*)(&data[string2_begin]),
+                            &data[string2_begin],
                             length, zlibsettings);
     if(error) break;
     ucvector_push_back(&decoded, 0);
@@ -4374,18 +4415,16 @@ static unsigned readChunk_zTXt(LodePNGInfo* info, const LodePNGDecompressSetting
 
 /*international text chunk (iTXt)*/
 static unsigned readChunk_iTXt(LodePNGInfo* info, const LodePNGDecompressSettings* zlibsettings,
-                               const unsigned char* data, size_t chunkLength)
-{
+                               const unsigned char* data, size_t chunkLength) {
   unsigned error = 0;
   unsigned i;
 
   unsigned length, begin, compressed;
   char *key = 0, *langtag = 0, *transkey = 0;
   ucvector decoded;
-  ucvector_init(&decoded);
+  ucvector_init(&decoded); /* TODO: only use in case of compressed text */
 
-  while(!error) /*not really a while loop, only used to break on error*/
-  {
+  while(!error) /*not really a while loop, only used to break on error*/ {
     /*Quick check if the chunk length isn't too small. Even without check
     it'd still fail with other error checks below if it's too short. This just gives a different error code.*/
     if(chunkLength < 5) CERROR_BREAK(error, 30); /*iTXt chunk too short*/
@@ -4433,20 +4472,17 @@ static unsigned readChunk_iTXt(LodePNGInfo* info, const LodePNGDecompressSetting
     /*read the actual text*/
     begin += length + 1;
 
-    length = chunkLength < begin ? 0 : chunkLength - begin;
+    length = (unsigned)chunkLength < begin ? 0 : (unsigned)chunkLength - begin;
 
-    if(compressed)
-    {
+    if(compressed) {
       /*will fail if zlib error, e.g. if length is too small*/
       error = zlib_decompress(&decoded.data, &decoded.size,
-                              (unsigned char*)(&data[begin]),
+                              &data[begin],
                               length, zlibsettings);
       if(error) break;
       if(decoded.allocsize < decoded.size) decoded.allocsize = decoded.size;
       ucvector_push_back(&decoded, 0);
-    }
-    else
-    {
+    } else {
       if(!ucvector_resize(&decoded, length + 1)) CERROR_BREAK(error, 83 /*alloc fail*/);
 
       decoded.data[length] = 0;
@@ -4466,8 +4502,7 @@ static unsigned readChunk_iTXt(LodePNGInfo* info, const LodePNGDecompressSetting
   return error;
 }
 
-static unsigned readChunk_tIME(LodePNGInfo* info, const unsigned char* data, size_t chunkLength)
-{
+static unsigned readChunk_tIME(LodePNGInfo* info, const unsigned char* data, size_t chunkLength) {
   if(chunkLength != 7) return 73; /*invalid tIME chunk size*/
 
   info->time_defined = 1;
@@ -4481,8 +4516,7 @@ static unsigned readChunk_tIME(LodePNGInfo* info, const unsigned char* data, siz
   return 0; /* OK */
 }
 
-static unsigned readChunk_pHYs(LodePNGInfo* info, const unsigned char* data, size_t chunkLength)
-{
+static unsigned readChunk_pHYs(LodePNGInfo* info, const unsigned char* data, size_t chunkLength) {
   if(chunkLength != 9) return 74; /*invalid pHYs chunk size*/
 
   info->phys_defined = 1;
@@ -4492,21 +4526,153 @@ static unsigned readChunk_pHYs(LodePNGInfo* info, const unsigned char* data, siz
 
   return 0; /* OK */
 }
+
+static unsigned readChunk_gAMA(LodePNGInfo* info, const unsigned char* data, size_t chunkLength) {
+  if(chunkLength != 4) return 96; /*invalid gAMA chunk size*/
+
+  info->gama_defined = 1;
+  info->gama_gamma = 16777216u * data[0] + 65536u * data[1] + 256u * data[2] + data[3];
+
+  return 0; /* OK */
+}
+
+static unsigned readChunk_cHRM(LodePNGInfo* info, const unsigned char* data, size_t chunkLength) {
+  if(chunkLength != 32) return 97; /*invalid cHRM chunk size*/
+
+  info->chrm_defined = 1;
+  info->chrm_white_x = 16777216u * data[ 0] + 65536u * data[ 1] + 256u * data[ 2] + data[ 3];
+  info->chrm_white_y = 16777216u * data[ 4] + 65536u * data[ 5] + 256u * data[ 6] + data[ 7];
+  info->chrm_red_x   = 16777216u * data[ 8] + 65536u * data[ 9] + 256u * data[10] + data[11];
+  info->chrm_red_y   = 16777216u * data[12] + 65536u * data[13] + 256u * data[14] + data[15];
+  info->chrm_green_x = 16777216u * data[16] + 65536u * data[17] + 256u * data[18] + data[19];
+  info->chrm_green_y = 16777216u * data[20] + 65536u * data[21] + 256u * data[22] + data[23];
+  info->chrm_blue_x  = 16777216u * data[24] + 65536u * data[25] + 256u * data[26] + data[27];
+  info->chrm_blue_y  = 16777216u * data[28] + 65536u * data[29] + 256u * data[30] + data[31];
+
+  return 0; /* OK */
+}
+
+static unsigned readChunk_sRGB(LodePNGInfo* info, const unsigned char* data, size_t chunkLength) {
+  if(chunkLength != 1) return 98; /*invalid sRGB chunk size (this one is never ignored)*/
+
+  info->srgb_defined = 1;
+  info->srgb_intent = data[0];
+
+  return 0; /* OK */
+}
+
+static unsigned readChunk_iCCP(LodePNGInfo* info, const LodePNGDecompressSettings* zlibsettings,
+                               const unsigned char* data, size_t chunkLength) {
+  unsigned error = 0;
+  unsigned i;
+
+  unsigned length, string2_begin;
+  ucvector decoded;
+
+  info->iccp_defined = 1;
+  if(info->iccp_name) lodepng_clear_icc(info);
+
+  for(length = 0; length < chunkLength && data[length] != 0; ++length) ;
+  if(length + 2 >= chunkLength) return 75; /*no null termination, corrupt?*/
+  if(length < 1 || length > 79) return 89; /*keyword too short or long*/
+
+  info->iccp_name = (char*)lodepng_malloc(length + 1);
+  if(!info->iccp_name) return 83; /*alloc fail*/
+
+  info->iccp_name[length] = 0;
+  for(i = 0; i != length; ++i) info->iccp_name[i] = (char)data[i];
+
+  if(data[length + 1] != 0) return 72; /*the 0 byte indicating compression must be 0*/
+
+  string2_begin = length + 2;
+  if(string2_begin > chunkLength) return 75; /*no null termination, corrupt?*/
+
+  length = (unsigned)chunkLength - string2_begin;
+  ucvector_init(&decoded);
+  error = zlib_decompress(&decoded.data, &decoded.size,
+                          &data[string2_begin],
+                          length, zlibsettings);
+  if(!error) {
+    if(decoded.size) {
+      info->iccp_profile_size = decoded.size;
+      info->iccp_profile = (unsigned char*)lodepng_malloc(decoded.size);
+      if(info->iccp_profile) {
+        lodepng_memcpy(info->iccp_profile, decoded.data, decoded.size);
+      } else {
+        error = 83; /* alloc fail */
+      }
+    } else {
+      error = 100; /*invalid ICC profile size*/
+    }
+  }
+  ucvector_cleanup(&decoded);
+  return error;
+}
+#endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/
+
+unsigned lodepng_inspect_chunk(LodePNGState* state, size_t pos,
+                               const unsigned char* in, size_t insize) {
+  const unsigned char* chunk = in + pos;
+  unsigned chunkLength;
+  const unsigned char* data;
+  unsigned unhandled = 0;
+  unsigned error = 0;
+
+  if (pos + 4 > insize) return 30;
+  chunkLength = lodepng_chunk_length(chunk);
+  if(chunkLength > 2147483647) return 63;
+  data = lodepng_chunk_data_const(chunk);
+  if(data + chunkLength + 4 > in + insize) return 30;
+
+  if(lodepng_chunk_type_equals(chunk, "PLTE")) {
+    error = readChunk_PLTE(&state->info_png.color, data, chunkLength);
+  } else if(lodepng_chunk_type_equals(chunk, "tRNS")) {
+    error = readChunk_tRNS(&state->info_png.color, data, chunkLength);
+#ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS
+  } else if(lodepng_chunk_type_equals(chunk, "bKGD")) {
+    error = readChunk_bKGD(&state->info_png, data, chunkLength);
+  } else if(lodepng_chunk_type_equals(chunk, "tEXt")) {
+    error = readChunk_tEXt(&state->info_png, data, chunkLength);
+  } else if(lodepng_chunk_type_equals(chunk, "zTXt")) {
+    error = readChunk_zTXt(&state->info_png, &state->decoder.zlibsettings, data, chunkLength);
+  } else if(lodepng_chunk_type_equals(chunk, "iTXt")) {
+    error = readChunk_iTXt(&state->info_png, &state->decoder.zlibsettings, data, chunkLength);
+  } else if(lodepng_chunk_type_equals(chunk, "tIME")) {
+    error = readChunk_tIME(&state->info_png, data, chunkLength);
+  } else if(lodepng_chunk_type_equals(chunk, "pHYs")) {
+    error = readChunk_pHYs(&state->info_png, data, chunkLength);
+  } else if(lodepng_chunk_type_equals(chunk, "gAMA")) {
+    error = readChunk_gAMA(&state->info_png, data, chunkLength);
+  } else if(lodepng_chunk_type_equals(chunk, "cHRM")) {
+    error = readChunk_cHRM(&state->info_png, data, chunkLength);
+  } else if(lodepng_chunk_type_equals(chunk, "sRGB")) {
+    error = readChunk_sRGB(&state->info_png, data, chunkLength);
+  } else if(lodepng_chunk_type_equals(chunk, "iCCP")) {
+    error = readChunk_iCCP(&state->info_png, &state->decoder.zlibsettings, data, chunkLength);
 #endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/
+  } else {
+    /* unhandled chunk is ok (is not an error) */
+    unhandled = 1;
+  }
+
+  if(!error && !unhandled && !state->decoder.ignore_crc) {
+    if(lodepng_chunk_check_crc(chunk)) return 57; /*invalid CRC*/
+  }
+
+  return error;
+}
 
 /*read a PNG, the result will be in the same color type as the PNG (hence "generic")*/
 static void decodeGeneric(unsigned char** out, unsigned* w, unsigned* h,
                           LodePNGState* state,
-                          const unsigned char* in, size_t insize)
-{
+                          const unsigned char* in, size_t insize) {
   unsigned char IEND = 0;
   const unsigned char* chunk;
   size_t i;
   ucvector idat; /*the data from idat chunks*/
-  ucvector scanlines;
-  size_t predict;
-  size_t numpixels;
-  size_t outsize;
+  unsigned char* scanlines = 0;
+  size_t scanlines_size = 0, expected_size = 0;
+  size_t outsize = 0;
 
   /*for unknown chunk order*/
   unsigned unknown = 0;
@@ -4514,129 +4680,126 @@ static void decodeGeneric(unsigned char** out, unsigned* w, unsigned* h,
   unsigned critical_pos = 1; /*1 = after IHDR, 2 = after PLTE, 3 = after IDAT*/
 #endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/
 
-  /*provide some proper output values if error will happen*/
+
+  /* safe output values in case error happens */
   *out = 0;
+  *w = *h = 0;
 
   state->error = lodepng_inspect(w, h, state, in, insize); /*reads header and resets other parameters in state->info_png*/
   if(state->error) return;
 
-  numpixels = *w * *h;
-
-  /*multiplication overflow*/
-  if(*h != 0 && numpixels / *h != *w) CERROR_RETURN(state->error, 92);
-  /*multiplication overflow possible further below. Allows up to 2^31-1 pixel
-  bytes with 16-bit RGBA, the rest is room for filter bytes.*/
-  if(numpixels > 268435455) CERROR_RETURN(state->error, 92);
+  if(lodepng_pixel_overflow(*w, *h, &state->info_png.color, &state->info_raw)) {
+    CERROR_RETURN(state->error, 92); /*overflow possible due to amount of pixels*/
+  }
 
   ucvector_init(&idat);
   chunk = &in[33]; /*first byte of the first chunk after the header*/
 
   /*loop through the chunks, ignoring unknown chunks and stopping at IEND chunk.
   IDAT data is put at the start of the in buffer*/
-  while(!IEND && !state->error)
-  {
+  while(!IEND && !state->error) {
     unsigned chunkLength;
     const unsigned char* data; /*the data in the chunk*/
 
     /*error: size of the in buffer too small to contain next chunk*/
-    if((size_t)((chunk - in) + 12) > insize || chunk < in) CERROR_BREAK(state->error, 30);
+    if((size_t)((chunk - in) + 12) > insize || chunk < in) {
+      if(state->decoder.ignore_end) break; /*other errors may still happen though*/
+      CERROR_BREAK(state->error, 30);
+    }
 
     /*length of the data of the chunk, excluding the length bytes, chunk type and CRC bytes*/
     chunkLength = lodepng_chunk_length(chunk);
     /*error: chunk length larger than the max PNG chunk size*/
-    if(chunkLength > 2147483647) CERROR_BREAK(state->error, 63);
+    if(chunkLength > 2147483647) {
+      if(state->decoder.ignore_end) break; /*other errors may still happen though*/
+      CERROR_BREAK(state->error, 63);
+    }
 
-    if((size_t)((chunk - in) + chunkLength + 12) > insize || (chunk + chunkLength + 12) < in)
-    {
+    if((size_t)((chunk - in) + chunkLength + 12) > insize || (chunk + chunkLength + 12) < in) {
       CERROR_BREAK(state->error, 64); /*error: size of the in buffer too small to contain next chunk*/
     }
 
     data = lodepng_chunk_data_const(chunk);
 
+    unknown = 0;
+
     /*IDAT chunk, containing compressed image data*/
-    if(lodepng_chunk_type_equals(chunk, "IDAT"))
-    {
+    if(lodepng_chunk_type_equals(chunk, "IDAT")) {
       size_t oldsize = idat.size;
-      if(!ucvector_resize(&idat, oldsize + chunkLength)) CERROR_BREAK(state->error, 83 /*alloc fail*/);
+      size_t newsize;
+      if(lodepng_addofl(oldsize, chunkLength, &newsize)) CERROR_BREAK(state->error, 95);
+      if(!ucvector_resize(&idat, newsize)) CERROR_BREAK(state->error, 83 /*alloc fail*/);
       for(i = 0; i != chunkLength; ++i) idat.data[oldsize + i] = data[i];
 #ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS
       critical_pos = 3;
 #endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/
-    }
-    /*IEND chunk*/
-    else if(lodepng_chunk_type_equals(chunk, "IEND"))
-    {
+    } else if(lodepng_chunk_type_equals(chunk, "IEND")) {
+      /*IEND chunk*/
       IEND = 1;
-    }
-    /*palette chunk (PLTE)*/
-    else if(lodepng_chunk_type_equals(chunk, "PLTE"))
-    {
+    } else if(lodepng_chunk_type_equals(chunk, "PLTE")) {
+      /*palette chunk (PLTE)*/
       state->error = readChunk_PLTE(&state->info_png.color, data, chunkLength);
       if(state->error) break;
 #ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS
       critical_pos = 2;
 #endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/
-    }
-    /*palette transparency chunk (tRNS)*/
-    else if(lodepng_chunk_type_equals(chunk, "tRNS"))
-    {
+    } else if(lodepng_chunk_type_equals(chunk, "tRNS")) {
+      /*palette transparency chunk (tRNS). Even though this one is an ancillary chunk , it is still compiled
+      in without 'LODEPNG_COMPILE_ANCILLARY_CHUNKS' because it contains essential color information that
+      affects the alpha channel of pixels. */
       state->error = readChunk_tRNS(&state->info_png.color, data, chunkLength);
       if(state->error) break;
-    }
 #ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS
-    /*background color chunk (bKGD)*/
-    else if(lodepng_chunk_type_equals(chunk, "bKGD"))
-    {
+      /*background color chunk (bKGD)*/
+    } else if(lodepng_chunk_type_equals(chunk, "bKGD")) {
       state->error = readChunk_bKGD(&state->info_png, data, chunkLength);
       if(state->error) break;
-    }
-    /*text chunk (tEXt)*/
-    else if(lodepng_chunk_type_equals(chunk, "tEXt"))
-    {
-      if(state->decoder.read_text_chunks)
-      {
+    } else if(lodepng_chunk_type_equals(chunk, "tEXt")) {
+      /*text chunk (tEXt)*/
+      if(state->decoder.read_text_chunks) {
         state->error = readChunk_tEXt(&state->info_png, data, chunkLength);
         if(state->error) break;
       }
-    }
-    /*compressed text chunk (zTXt)*/
-    else if(lodepng_chunk_type_equals(chunk, "zTXt"))
-    {
-      if(state->decoder.read_text_chunks)
-      {
+    } else if(lodepng_chunk_type_equals(chunk, "zTXt")) {
+      /*compressed text chunk (zTXt)*/
+      if(state->decoder.read_text_chunks) {
         state->error = readChunk_zTXt(&state->info_png, &state->decoder.zlibsettings, data, chunkLength);
         if(state->error) break;
       }
-    }
-    /*international text chunk (iTXt)*/
-    else if(lodepng_chunk_type_equals(chunk, "iTXt"))
-    {
-      if(state->decoder.read_text_chunks)
-      {
+    } else if(lodepng_chunk_type_equals(chunk, "iTXt")) {
+      /*international text chunk (iTXt)*/
+      if(state->decoder.read_text_chunks) {
         state->error = readChunk_iTXt(&state->info_png, &state->decoder.zlibsettings, data, chunkLength);
         if(state->error) break;
       }
-    }
-    else if(lodepng_chunk_type_equals(chunk, "tIME"))
-    {
+    } else if(lodepng_chunk_type_equals(chunk, "tIME")) {
       state->error = readChunk_tIME(&state->info_png, data, chunkLength);
       if(state->error) break;
-    }
-    else if(lodepng_chunk_type_equals(chunk, "pHYs"))
-    {
+    } else if(lodepng_chunk_type_equals(chunk, "pHYs")) {
       state->error = readChunk_pHYs(&state->info_png, data, chunkLength);
       if(state->error) break;
-    }
+    } else if(lodepng_chunk_type_equals(chunk, "gAMA")) {
+      state->error = readChunk_gAMA(&state->info_png, data, chunkLength);
+      if(state->error) break;
+    } else if(lodepng_chunk_type_equals(chunk, "cHRM")) {
+      state->error = readChunk_cHRM(&state->info_png, data, chunkLength);
+      if(state->error) break;
+    } else if(lodepng_chunk_type_equals(chunk, "sRGB")) {
+      state->error = readChunk_sRGB(&state->info_png, data, chunkLength);
+      if(state->error) break;
+    } else if(lodepng_chunk_type_equals(chunk, "iCCP")) {
+      state->error = readChunk_iCCP(&state->info_png, &state->decoder.zlibsettings, data, chunkLength);
+      if(state->error) break;
 #endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/
-    else /*it's not an implemented chunk type, so ignore it: skip over the data*/
-    {
+    } else /*it's not an implemented chunk type, so ignore it: skip over the data*/ {
       /*error: unknown critical chunk (5th bit of first byte of chunk type is 0)*/
-      if(!lodepng_chunk_ancillary(chunk)) CERROR_BREAK(state->error, 69);
+      if(!state->decoder.ignore_critical && !lodepng_chunk_ancillary(chunk)) {
+        CERROR_BREAK(state->error, 69);
+      }
 
       unknown = 1;
 #ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS
-      if(state->decoder.remember_unknown_chunks)
-      {
+      if(state->decoder.remember_unknown_chunks) {
         state->error = lodepng_chunk_append(&state->info_png.unknown_chunks_data[critical_pos - 1],
                                             &state->info_png.unknown_chunks_size[critical_pos - 1], chunk);
         if(state->error) break;
@@ -4644,94 +4807,86 @@ static void decodeGeneric(unsigned char** out, unsigned* w, unsigned* h,
 #endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/
     }
 
-    if(!state->decoder.ignore_crc && !unknown) /*check CRC if wanted, only on known chunk types*/
-    {
+    if(!state->decoder.ignore_crc && !unknown) /*check CRC if wanted, only on known chunk types*/ {
       if(lodepng_chunk_check_crc(chunk)) CERROR_BREAK(state->error, 57); /*invalid CRC*/
     }
 
     if(!IEND) chunk = lodepng_chunk_next_const(chunk);
   }
 
-  ucvector_init(&scanlines);
   /*predict output size, to allocate exact size for output buffer to avoid more dynamic allocation.
   If the decompressed size does not match the prediction, the image must be corrupt.*/
-  if(state->info_png.interlace_method == 0)
-  {
-    /*The extra *h is added because this are the filter bytes every scanline starts with*/
-    predict = lodepng_get_raw_size_idat(*w, *h, &state->info_png.color) + *h;
-  }
-  else
-  {
-    /*Adam-7 interlaced: predicted size is the sum of the 7 sub-images sizes*/
+  if(state->info_png.interlace_method == 0) {
+    expected_size = lodepng_get_raw_size_idat(*w, *h, &state->info_png.color);
+  } else {
+    /*Adam-7 interlaced: expected size is the sum of the 7 sub-images sizes*/
     const LodePNGColorMode* color = &state->info_png.color;
-    predict = 0;
-    predict += lodepng_get_raw_size_idat((*w + 7) >> 3, (*h + 7) >> 3, color) + ((*h + 7) >> 3);
-    if(*w > 4) predict += lodepng_get_raw_size_idat((*w + 3) >> 3, (*h + 7) >> 3, color) + ((*h + 7) >> 3);
-    predict += lodepng_get_raw_size_idat((*w + 3) >> 2, (*h + 3) >> 3, color) + ((*h + 3) >> 3);
-    if(*w > 2) predict += lodepng_get_raw_size_idat((*w + 1) >> 2, (*h + 3) >> 2, color) + ((*h + 3) >> 2);
-    predict += lodepng_get_raw_size_idat((*w + 1) >> 1, (*h + 1) >> 2, color) + ((*h + 1) >> 2);
-    if(*w > 1) predict += lodepng_get_raw_size_idat((*w + 0) >> 1, (*h + 1) >> 1, color) + ((*h + 1) >> 1);
-    predict += lodepng_get_raw_size_idat((*w + 0), (*h + 0) >> 1, color) + ((*h + 0) >> 1);
-  }
-  if(!state->error && !ucvector_reserve(&scanlines, predict)) state->error = 83; /*alloc fail*/
-  if(!state->error)
-  {
-    state->error = zlib_decompress(&scanlines.data, &scanlines.size, idat.data,
+    expected_size = 0;
+    expected_size += lodepng_get_raw_size_idat((*w + 7) >> 3, (*h + 7) >> 3, color);
+    if(*w > 4) expected_size += lodepng_get_raw_size_idat((*w + 3) >> 3, (*h + 7) >> 3, color);
+    expected_size += lodepng_get_raw_size_idat((*w + 3) >> 2, (*h + 3) >> 3, color);
+    if(*w > 2) expected_size += lodepng_get_raw_size_idat((*w + 1) >> 2, (*h + 3) >> 2, color);
+    expected_size += lodepng_get_raw_size_idat((*w + 1) >> 1, (*h + 1) >> 2, color);
+    if(*w > 1) expected_size += lodepng_get_raw_size_idat((*w + 0) >> 1, (*h + 1) >> 1, color);
+    expected_size += lodepng_get_raw_size_idat((*w + 0), (*h + 0) >> 1, color);
+  }
+  if(!state->error) {
+    /* This allocated data will be realloced by zlib_decompress, initially at
+    smaller size again. But the fact that it's already allocated at full size
+    here speeds the multiple reallocs up. TODO: make zlib_decompress support
+    receiving already allocated buffer with expected size instead. */
+    scanlines = (unsigned char*)lodepng_malloc(expected_size);
+    if(!scanlines) state->error = 83; /*alloc fail*/
+    scanlines_size = 0;
+  }
+  if(!state->error) {
+    state->error = zlib_decompress(&scanlines, &scanlines_size, idat.data,
                                    idat.size, &state->decoder.zlibsettings);
-    if(!state->error && scanlines.size != predict) state->error = 91; /*decompressed size doesn't match prediction*/
+    if(!state->error && scanlines_size != expected_size) state->error = 91; /*decompressed size doesn't match prediction*/
   }
   ucvector_cleanup(&idat);
 
-  if(!state->error)
-  {
+  if(!state->error) {
     outsize = lodepng_get_raw_size(*w, *h, &state->info_png.color);
     *out = (unsigned char*)lodepng_malloc(outsize);
     if(!*out) state->error = 83; /*alloc fail*/
   }
-  if(!state->error)
-  {
+  if(!state->error) {
     for(i = 0; i < outsize; i++) (*out)[i] = 0;
-    state->error = postProcessScanlines(*out, scanlines.data, *w, *h, &state->info_png);
+    state->error = postProcessScanlines(*out, scanlines, *w, *h, &state->info_png);
   }
-  ucvector_cleanup(&scanlines);
+  lodepng_free(scanlines);
 }
 
 unsigned lodepng_decode(unsigned char** out, unsigned* w, unsigned* h,
                         LodePNGState* state,
-                        const unsigned char* in, size_t insize)
-{
+                        const unsigned char* in, size_t insize) {
   *out = 0;
   decodeGeneric(out, w, h, state, in, insize);
   if(state->error) return state->error;
-  if(!state->decoder.color_convert || lodepng_color_mode_equal(&state->info_raw, &state->info_png.color))
-  {
+  if(!state->decoder.color_convert || lodepng_color_mode_equal(&state->info_raw, &state->info_png.color)) {
     /*same color type, no copying or converting of data needed*/
     /*store the info_png color settings on the info_raw so that the info_raw still reflects what colortype
     the raw image has to the end user*/
-    if(!state->decoder.color_convert)
-    {
+    if(!state->decoder.color_convert) {
       state->error = lodepng_color_mode_copy(&state->info_raw, &state->info_png.color);
       if(state->error) return state->error;
     }
-  }
-  else
-  {
+  } else {
     /*color conversion needed; sort of copy of the data*/
     unsigned char* data = *out;
     size_t outsize;
 
     /*TODO: check if this works according to the statement in the documentation: "The converter can convert
-    from greyscale input color type, to 8-bit greyscale or greyscale with alpha"*/
+    from grayscale input color type, to 8-bit grayscale or grayscale with alpha"*/
     if(!(state->info_raw.colortype == LCT_RGB || state->info_raw.colortype == LCT_RGBA)
-       && !(state->info_raw.bitdepth == 8))
-    {
+       && !(state->info_raw.bitdepth == 8)) {
       return 56; /*unsupported color mode conversion*/
     }
 
     outsize = lodepng_get_raw_size(*w, *h, &state->info_raw);
     *out = (unsigned char*)lodepng_malloc(outsize);
-    if(!(*out))
-    {
+    if(!(*out)) {
       state->error = 83; /*alloc fail*/
     }
     else state->error = lodepng_convert(*out, data, &state->info_raw,
@@ -4742,8 +4897,7 @@ unsigned lodepng_decode(unsigned char** out, unsigned* w, unsigned* h,
 }
 
 unsigned lodepng_decode_memory(unsigned char** out, unsigned* w, unsigned* h, const unsigned char* in,
-                               size_t insize, LodePNGColorType colortype, unsigned bitdepth)
-{
+                               size_t insize, LodePNGColorType colortype, unsigned bitdepth) {
   unsigned error;
   LodePNGState state;
   lodepng_state_init(&state);
@@ -4754,48 +4908,47 @@ unsigned lodepng_decode_memory(unsigned char** out, unsigned* w, unsigned* h, co
   return error;
 }
 
-unsigned lodepng_decode32(unsigned char** out, unsigned* w, unsigned* h, const unsigned char* in, size_t insize)
-{
+unsigned lodepng_decode32(unsigned char** out, unsigned* w, unsigned* h, const unsigned char* in, size_t insize) {
   return lodepng_decode_memory(out, w, h, in, insize, LCT_RGBA, 8);
 }
 
-unsigned lodepng_decode24(unsigned char** out, unsigned* w, unsigned* h, const unsigned char* in, size_t insize)
-{
+unsigned lodepng_decode24(unsigned char** out, unsigned* w, unsigned* h, const unsigned char* in, size_t insize) {
   return lodepng_decode_memory(out, w, h, in, insize, LCT_RGB, 8);
 }
 
 #ifdef LODEPNG_COMPILE_DISK
 unsigned lodepng_decode_file(unsigned char** out, unsigned* w, unsigned* h, const char* filename,
-                             LodePNGColorType colortype, unsigned bitdepth)
-{
+                             LodePNGColorType colortype, unsigned bitdepth) {
   unsigned char* buffer = 0;
   size_t buffersize;
   unsigned error;
+  /* safe output values in case error happens */
+  *out = 0;
+  *w = *h = 0;
   error = lodepng_load_file(&buffer, &buffersize, filename);
   if(!error) error = lodepng_decode_memory(out, w, h, buffer, buffersize, colortype, bitdepth);
   lodepng_free(buffer);
   return error;
 }
 
-unsigned lodepng_decode32_file(unsigned char** out, unsigned* w, unsigned* h, const char* filename)
-{
+unsigned lodepng_decode32_file(unsigned char** out, unsigned* w, unsigned* h, const char* filename) {
   return lodepng_decode_file(out, w, h, filename, LCT_RGBA, 8);
 }
 
-unsigned lodepng_decode24_file(unsigned char** out, unsigned* w, unsigned* h, const char* filename)
-{
+unsigned lodepng_decode24_file(unsigned char** out, unsigned* w, unsigned* h, const char* filename) {
   return lodepng_decode_file(out, w, h, filename, LCT_RGB, 8);
 }
 #endif /*LODEPNG_COMPILE_DISK*/
 
-void lodepng_decoder_settings_init(LodePNGDecoderSettings* settings)
-{
+void lodepng_decoder_settings_init(LodePNGDecoderSettings* settings) {
   settings->color_convert = 1;
 #ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS
   settings->read_text_chunks = 1;
   settings->remember_unknown_chunks = 0;
 #endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/
   settings->ignore_crc = 0;
+  settings->ignore_critical = 0;
+  settings->ignore_end = 0;
   lodepng_decompress_settings_init(&settings->zlibsettings);
 }
 
@@ -4803,8 +4956,7 @@ void lodepng_decoder_settings_init(LodePNGDecoderSettings* settings)
 
 #if defined(LODEPNG_COMPILE_DECODER) || defined(LODEPNG_COMPILE_ENCODER)
 
-void lodepng_state_init(LodePNGState* state)
-{
+void lodepng_state_init(LodePNGState* state) {
 #ifdef LODEPNG_COMPILE_DECODER
   lodepng_decoder_settings_init(&state->decoder);
 #endif /*LODEPNG_COMPILE_DECODER*/
@@ -4816,14 +4968,12 @@ void lodepng_state_init(LodePNGState* state)
   state->error = 1;
 }
 
-void lodepng_state_cleanup(LodePNGState* state)
-{
+void lodepng_state_cleanup(LodePNGState* state) {
   lodepng_color_mode_cleanup(&state->info_raw);
   lodepng_info_cleanup(&state->info_png);
 }
 
-void lodepng_state_copy(LodePNGState* dest, const LodePNGState* source)
-{
+void lodepng_state_copy(LodePNGState* dest, const LodePNGState* source) {
   lodepng_state_cleanup(dest);
   *dest = *source;
   lodepng_color_mode_init(&dest->info_raw);
@@ -4841,15 +4991,13 @@ void lodepng_state_copy(LodePNGState* dest, const LodePNGState* source)
 /* ////////////////////////////////////////////////////////////////////////// */
 
 /*chunkName must be string of 4 characters*/
-static unsigned addChunk(ucvector* out, const char* chunkName, const unsigned char* data, size_t length)
-{
+static unsigned addChunk(ucvector* out, const char* chunkName, const unsigned char* data, size_t length) {
   CERROR_TRY_RETURN(lodepng_chunk_create(&out->data, &out->size, (unsigned)length, chunkName, data));
   out->allocsize = out->size; /*fix the allocsize again*/
   return 0;
 }
 
-static void writeSignature(ucvector* out)
-{
+static void writeSignature(ucvector* out) {
   /*8 bytes PNG signature, aka the magic bytes*/
   ucvector_push_back(out, 137);
   ucvector_push_back(out, 80);
@@ -4862,34 +5010,26 @@ static void writeSignature(ucvector* out)
 }
 
 static unsigned addChunk_IHDR(ucvector* out, unsigned w, unsigned h,
-                              LodePNGColorType colortype, unsigned bitdepth, unsigned interlace_method)
-{
-  unsigned error = 0;
-  ucvector header;
-  ucvector_init(&header);
-
-  lodepng_add32bitInt(&header, w); /*width*/
-  lodepng_add32bitInt(&header, h); /*height*/
-  ucvector_push_back(&header, (unsigned char)bitdepth); /*bit depth*/
-  ucvector_push_back(&header, (unsigned char)colortype); /*color type*/
-  ucvector_push_back(&header, 0); /*compression method*/
-  ucvector_push_back(&header, 0); /*filter method*/
-  ucvector_push_back(&header, interlace_method); /*interlace method*/
+                              LodePNGColorType colortype, unsigned bitdepth, unsigned interlace_method) {
+  unsigned char data[13];
 
-  error = addChunk(out, "IHDR", header.data, header.size);
-  ucvector_cleanup(&header);
+  lodepng_set32bitInt(data + 0, w); /*width*/
+  lodepng_set32bitInt(data + 4, h); /*height*/
+  data[8] = (unsigned char)bitdepth; /*bit depth*/
+  data[9] = (unsigned char)colortype; /*color type*/
+  data[10] = 0; /*compression method*/
+  data[11] = 0; /*filter method*/
+  data[12] = interlace_method; /*interlace method*/
 
-  return error;
+  return addChunk(out, "IHDR", data, sizeof(data));
 }
 
-static unsigned addChunk_PLTE(ucvector* out, const LodePNGColorMode* info)
-{
+static unsigned addChunk_PLTE(ucvector* out, const LodePNGColorMode* info) {
   unsigned error = 0;
   size_t i;
   ucvector PLTE;
   ucvector_init(&PLTE);
-  for(i = 0; i != info->palettesize * 4; ++i)
-  {
+  for(i = 0; i != info->palettesize * 4; ++i) {
     /*add all channels except alpha channel*/
     if(i % 4 != 3) ucvector_push_back(&PLTE, info->palette[i]);
   }
@@ -4899,36 +5039,27 @@ static unsigned addChunk_PLTE(ucvector* out, const LodePNGColorMode* info)
   return error;
 }
 
-static unsigned addChunk_tRNS(ucvector* out, const LodePNGColorMode* info)
-{
+static unsigned addChunk_tRNS(ucvector* out, const LodePNGColorMode* info) {
   unsigned error = 0;
   size_t i;
   ucvector tRNS;
   ucvector_init(&tRNS);
-  if(info->colortype == LCT_PALETTE)
-  {
+  if(info->colortype == LCT_PALETTE) {
     size_t amount = info->palettesize;
     /*the tail of palette values that all have 255 as alpha, does not have to be encoded*/
-    for(i = info->palettesize; i != 0; --i)
-    {
+    for(i = info->palettesize; i != 0; --i) {
       if(info->palette[4 * (i - 1) + 3] == 255) --amount;
       else break;
     }
     /*add only alpha channel*/
     for(i = 0; i != amount; ++i) ucvector_push_back(&tRNS, info->palette[4 * i + 3]);
-  }
-  else if(info->colortype == LCT_GREY)
-  {
-    if(info->key_defined)
-    {
+  } else if(info->colortype == LCT_GREY) {
+    if(info->key_defined) {
       ucvector_push_back(&tRNS, (unsigned char)(info->key_r >> 8));
       ucvector_push_back(&tRNS, (unsigned char)(info->key_r & 255));
     }
-  }
-  else if(info->colortype == LCT_RGB)
-  {
-    if(info->key_defined)
-    {
+  } else if(info->colortype == LCT_RGB) {
+    if(info->key_defined) {
       ucvector_push_back(&tRNS, (unsigned char)(info->key_r >> 8));
       ucvector_push_back(&tRNS, (unsigned char)(info->key_r & 255));
       ucvector_push_back(&tRNS, (unsigned char)(info->key_g >> 8));
@@ -4945,8 +5076,7 @@ static unsigned addChunk_tRNS(ucvector* out, const LodePNGColorMode* info)
 }
 
 static unsigned addChunk_IDAT(ucvector* out, const unsigned char* data, size_t datasize,
-                              LodePNGCompressSettings* zlibsettings)
-{
+                              LodePNGCompressSettings* zlibsettings) {
   ucvector zlibdata;
   unsigned error = 0;
 
@@ -4959,8 +5089,7 @@ static unsigned addChunk_IDAT(ucvector* out, const unsigned char* data, size_t d
   return error;
 }
 
-static unsigned addChunk_IEND(ucvector* out)
-{
+static unsigned addChunk_IEND(ucvector* out) {
   unsigned error = 0;
   error = addChunk(out, "IEND", 0, 0);
   return error;
@@ -4968,8 +5097,7 @@ static unsigned addChunk_IEND(ucvector* out)
 
 #ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS
 
-static unsigned addChunk_tEXt(ucvector* out, const char* keyword, const char* textstring)
-{
+static unsigned addChunk_tEXt(ucvector* out, const char* keyword, const char* textstring) {
   unsigned error = 0;
   size_t i;
   ucvector text;
@@ -4985,11 +5113,10 @@ static unsigned addChunk_tEXt(ucvector* out, const char* keyword, const char* te
 }
 
 static unsigned addChunk_zTXt(ucvector* out, const char* keyword, const char* textstring,
-                              LodePNGCompressSettings* zlibsettings)
-{
+                              LodePNGCompressSettings* zlibsettings) {
   unsigned error = 0;
   ucvector data, compressed;
-  size_t i, textsize = strlen(textstring);
+  size_t i, textsize = lodepng_strlen(textstring);
 
   ucvector_init(&data);
   ucvector_init(&compressed);
@@ -4999,9 +5126,8 @@ static unsigned addChunk_zTXt(ucvector* out, const char* keyword, const char* te
   ucvector_push_back(&data, 0); /*compression method: 0*/
 
   error = zlib_compress(&compressed.data, &compressed.size,
-                        (unsigned char*)textstring, textsize, zlibsettings);
-  if(!error)
-  {
+                        (const unsigned char*)textstring, textsize, zlibsettings);
+  if(!error) {
     for(i = 0; i != compressed.size; ++i) ucvector_push_back(&data, compressed.data[i]);
     error = addChunk(out, "zTXt", data.data, data.size);
   }
@@ -5012,11 +5138,10 @@ static unsigned addChunk_zTXt(ucvector* out, const char* keyword, const char* te
 }
 
 static unsigned addChunk_iTXt(ucvector* out, unsigned compressed, const char* keyword, const char* langtag,
-                              const char* transkey, const char* textstring, LodePNGCompressSettings* zlibsettings)
-{
+                              const char* transkey, const char* textstring, LodePNGCompressSettings* zlibsettings) {
   unsigned error = 0;
   ucvector data;
-  size_t i, textsize = strlen(textstring);
+  size_t i, textsize = lodepng_strlen(textstring);
 
   ucvector_init(&data);
 
@@ -5030,20 +5155,16 @@ static unsigned addChunk_iTXt(ucvector* out, unsigned compressed, const char* ke
   for(i = 0; transkey[i] != 0; ++i) ucvector_push_back(&data, (unsigned char)transkey[i]);
   ucvector_push_back(&data, 0); /*null termination char*/
 
-  if(compressed)
-  {
+  if(compressed) {
     ucvector compressed_data;
     ucvector_init(&compressed_data);
     error = zlib_compress(&compressed_data.data, &compressed_data.size,
-                          (unsigned char*)textstring, textsize, zlibsettings);
-    if(!error)
-    {
+                          (const unsigned char*)textstring, textsize, zlibsettings);
+    if(!error) {
       for(i = 0; i != compressed_data.size; ++i) ucvector_push_back(&data, compressed_data.data[i]);
     }
     ucvector_cleanup(&compressed_data);
-  }
-  else /*not compressed*/
-  {
+  } else /*not compressed*/ {
     for(i = 0; textstring[i] != 0; ++i) ucvector_push_back(&data, (unsigned char)textstring[i]);
   }
 
@@ -5052,41 +5173,30 @@ static unsigned addChunk_iTXt(ucvector* out, unsigned compressed, const char* ke
   return error;
 }
 
-static unsigned addChunk_bKGD(ucvector* out, const LodePNGInfo* info)
-{
-  unsigned error = 0;
-  ucvector bKGD;
-  ucvector_init(&bKGD);
-  if(info->color.colortype == LCT_GREY || info->color.colortype == LCT_GREY_ALPHA)
-  {
-    ucvector_push_back(&bKGD, (unsigned char)(info->background_r >> 8));
-    ucvector_push_back(&bKGD, (unsigned char)(info->background_r & 255));
-  }
-  else if(info->color.colortype == LCT_RGB || info->color.colortype == LCT_RGBA)
-  {
-    ucvector_push_back(&bKGD, (unsigned char)(info->background_r >> 8));
-    ucvector_push_back(&bKGD, (unsigned char)(info->background_r & 255));
-    ucvector_push_back(&bKGD, (unsigned char)(info->background_g >> 8));
-    ucvector_push_back(&bKGD, (unsigned char)(info->background_g & 255));
-    ucvector_push_back(&bKGD, (unsigned char)(info->background_b >> 8));
-    ucvector_push_back(&bKGD, (unsigned char)(info->background_b & 255));
-  }
-  else if(info->color.colortype == LCT_PALETTE)
-  {
-    ucvector_push_back(&bKGD, (unsigned char)(info->background_r & 255)); /*palette index*/
-  }
-
-  error = addChunk(out, "bKGD", bKGD.data, bKGD.size);
-  ucvector_cleanup(&bKGD);
-
-  return error;
-}
-
-static unsigned addChunk_tIME(ucvector* out, const LodePNGTime* time)
-{
-  unsigned error = 0;
-  unsigned char* data = (unsigned char*)lodepng_malloc(7);
-  if(!data) return 83; /*alloc fail*/
+static unsigned addChunk_bKGD(ucvector* out, const LodePNGInfo* info) {
+  unsigned char data[6];
+  size_t size = 0;
+  if(info->color.colortype == LCT_GREY || info->color.colortype == LCT_GREY_ALPHA) {
+    data[0] = (unsigned char)(info->background_r >> 8);
+    data[1] = (unsigned char)(info->background_r & 255);
+    size = 2;
+  } else if(info->color.colortype == LCT_RGB || info->color.colortype == LCT_RGBA) {
+    data[0] = (unsigned char)(info->background_r >> 8);
+    data[1] = (unsigned char)(info->background_r & 255);
+    data[2] = (unsigned char)(info->background_g >> 8);
+    data[3] = (unsigned char)(info->background_g & 255);
+    data[4] = (unsigned char)(info->background_b >> 8);
+    data[5] = (unsigned char)(info->background_b & 255);
+    size = 6;
+  } else if(info->color.colortype == LCT_PALETTE) {
+    data[0] =(unsigned char)(info->background_r & 255); /*palette index*/
+    size = 1;
+  }
+  return addChunk(out, "bKGD", data, size);
+}
+
+static unsigned addChunk_tIME(ucvector* out, const LodePNGTime* time) {
+  unsigned char data[7];
   data[0] = (unsigned char)(time->year >> 8);
   data[1] = (unsigned char)(time->year & 255);
   data[2] = (unsigned char)time->month;
@@ -5094,35 +5204,70 @@ static unsigned addChunk_tIME(ucvector* out, const LodePNGTime* time)
   data[4] = (unsigned char)time->hour;
   data[5] = (unsigned char)time->minute;
   data[6] = (unsigned char)time->second;
-  error = addChunk(out, "tIME", data, 7);
-  lodepng_free(data);
-  return error;
+  return addChunk(out, "tIME", data, sizeof(data));
+}
+
+static unsigned addChunk_pHYs(ucvector* out, const LodePNGInfo* info) {
+  unsigned char data[9];
+  lodepng_set32bitInt(data + 0, info->phys_x);
+  lodepng_set32bitInt(data + 4, info->phys_y);  data[8] = info->phys_unit;
+  return addChunk(out, "pHYs", data, sizeof(data));
 }
 
-static unsigned addChunk_pHYs(ucvector* out, const LodePNGInfo* info)
-{
+static unsigned addChunk_gAMA(ucvector* out, const LodePNGInfo* info) {
+  unsigned char data[4];
+  lodepng_set32bitInt(data, info->gama_gamma);
+  return addChunk(out, "gAMA", data, sizeof(data));
+}
+
+static unsigned addChunk_cHRM(ucvector* out, const LodePNGInfo* info) {
+  unsigned char data[32];
+  lodepng_set32bitInt(data + 0, info->chrm_white_x);
+  lodepng_set32bitInt(data + 4, info->chrm_white_y);
+  lodepng_set32bitInt(data + 8, info->chrm_red_x);
+  lodepng_set32bitInt(data + 12, info->chrm_red_y);
+  lodepng_set32bitInt(data + 16, info->chrm_green_x);
+  lodepng_set32bitInt(data + 20, info->chrm_green_y);
+  lodepng_set32bitInt(data + 24, info->chrm_blue_x);
+  lodepng_set32bitInt(data + 28, info->chrm_blue_y);
+  return addChunk(out, "cHRM", data, sizeof(data));
+}
+
+static unsigned addChunk_sRGB(ucvector* out, const LodePNGInfo* info) {
+  unsigned char data = info->srgb_intent;
+  return addChunk(out, "sRGB", &data, 1);
+}
+
+static unsigned addChunk_iCCP(ucvector* out, const LodePNGInfo* info, LodePNGCompressSettings* zlibsettings) {
   unsigned error = 0;
-  ucvector data;
+  ucvector data, compressed;
+  size_t i;
+
   ucvector_init(&data);
+  ucvector_init(&compressed);
+  for(i = 0; info->iccp_name[i] != 0; ++i) ucvector_push_back(&data, (unsigned char)info->iccp_name[i]);
+  if(i < 1 || i > 79) return 89; /*error: invalid keyword size*/
+  ucvector_push_back(&data, 0); /*0 termination char*/
+  ucvector_push_back(&data, 0); /*compression method: 0*/
 
-  lodepng_add32bitInt(&data, info->phys_x);
-  lodepng_add32bitInt(&data, info->phys_y);
-  ucvector_push_back(&data, info->phys_unit);
+  error = zlib_compress(&compressed.data, &compressed.size,
+                        info->iccp_profile, info->iccp_profile_size, zlibsettings);
+  if(!error) {
+    for(i = 0; i != compressed.size; ++i) ucvector_push_back(&data, compressed.data[i]);
+    error = addChunk(out, "iCCP", data.data, data.size);
+  }
 
-  error = addChunk(out, "pHYs", data.data, data.size);
+  ucvector_cleanup(&compressed);
   ucvector_cleanup(&data);
-
   return error;
 }
 
 #endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/
 
 static void filterScanline(unsigned char* out, const unsigned char* scanline, const unsigned char* prevline,
-                           size_t length, size_t bytewidth, unsigned char filterType)
-{
+                           size_t length, size_t bytewidth, unsigned char filterType) {
   size_t i;
-  switch(filterType)
-  {
+  switch(filterType) {
     case 0: /*None*/
       for(i = 0; i != length; ++i) out[i] = scanline[i];
       break;
@@ -5131,71 +5276,61 @@ static void filterScanline(unsigned char* out, const unsigned char* scanline, co
       for(i = bytewidth; i < length; ++i) out[i] = scanline[i] - scanline[i - bytewidth];
       break;
     case 2: /*Up*/
-      if(prevline)
-      {
+      if(prevline) {
         for(i = 0; i != length; ++i) out[i] = scanline[i] - prevline[i];
-      }
-      else
-      {
+      } else {
         for(i = 0; i != length; ++i) out[i] = scanline[i];
       }
       break;
     case 3: /*Average*/
-      if(prevline)
-      {
+      if(prevline) {
         for(i = 0; i != bytewidth; ++i) out[i] = scanline[i] - (prevline[i] >> 1);
         for(i = bytewidth; i < length; ++i) out[i] = scanline[i] - ((scanline[i - bytewidth] + prevline[i]) >> 1);
-      }
-      else
-      {
+      } else {
         for(i = 0; i != bytewidth; ++i) out[i] = scanline[i];
         for(i = bytewidth; i < length; ++i) out[i] = scanline[i] - (scanline[i - bytewidth] >> 1);
       }
       break;
     case 4: /*Paeth*/
-      if(prevline)
-      {
+      if(prevline) {
         /*paethPredictor(0, prevline[i], 0) is always prevline[i]*/
         for(i = 0; i != bytewidth; ++i) out[i] = (scanline[i] - prevline[i]);
-        for(i = bytewidth; i < length; ++i)
-        {
+        for(i = bytewidth; i < length; ++i) {
           out[i] = (scanline[i] - paethPredictor(scanline[i - bytewidth], prevline[i], prevline[i - bytewidth]));
         }
-      }
-      else
-      {
+      } else {
         for(i = 0; i != bytewidth; ++i) out[i] = scanline[i];
         /*paethPredictor(scanline[i - bytewidth], 0, 0) is always scanline[i - bytewidth]*/
         for(i = bytewidth; i < length; ++i) out[i] = (scanline[i] - scanline[i - bytewidth]);
       }
       break;
-    default: return; /*unexisting filter type given*/
+    default: return; /*nonexistent filter type given*/
   }
 }
 
-/* log2 approximation. A slight bit faster than std::log. */
-static float flog2(float f)
-{
-  float result = 0;
-  while(f > 32) { result += 4; f /= 16; }
-  while(f > 2) { ++result; f /= 2; }
-  return result + 1.442695f * (f * f * f / 3 - 3 * f * f / 2 + 3 * f - 1.83333f);
+/* integer binary logarithm */
+static size_t ilog2(size_t i) {
+  size_t result = 0;
+  while(i >= 65536) { result += 16; i >>= 16; }
+  while(i >= 256) { result += 8; i >>= 8; }
+  while(i >= 16) { result += 4; i >>= 4; }
+  while(i >= 2) { result += 1; i >>= 1; }
+  return result;
 }
 
 static unsigned filter(unsigned char* out, const unsigned char* in, unsigned w, unsigned h,
-                       const LodePNGColorMode* info, const LodePNGEncoderSettings* settings)
-{
+                       const LodePNGColorMode* info, const LodePNGEncoderSettings* settings) {
   /*
   For PNG filter method 0
-  out must be a buffer with as size: h + (w * h * bpp + 7) / 8, because there are
+  out must be a buffer with as size: h + (w * h * bpp + 7u) / 8u, because there are
   the scanlines with 1 extra byte per scanline
   */
 
   unsigned bpp = lodepng_get_bpp(info);
   /*the width of a scanline in bytes, not including the filter type*/
-  size_t linebytes = (w * bpp + 7) / 8;
+  size_t linebytes = (w * bpp + 7u) / 8u;
   /*bytewidth is used for filtering, is 1 when bpp < 8, number of bytes per pixel otherwise*/
-  size_t bytewidth = (bpp + 7) / 8;
+  size_t bytewidth = (bpp + 7u) / 8u;
   const unsigned char* prevline = 0;
   unsigned x, y;
   unsigned error = 0;
@@ -5219,50 +5354,39 @@ static unsigned filter(unsigned char* out, const unsigned char* in, unsigned w,
 
   if(bpp == 0) return 31; /*error: invalid color type*/
 
-  if(strategy == LFS_ZERO)
-  {
-    for(y = 0; y != h; ++y)
-    {
+  if(strategy >= LFS_ZERO && strategy <= LFS_FOUR) {
+    unsigned char type = (unsigned char)strategy;
+    for(y = 0; y != h; ++y) {
       size_t outindex = (1 + linebytes) * y; /*the extra filterbyte added to each row*/
       size_t inindex = linebytes * y;
-      out[outindex] = 0; /*filter type byte*/
-      filterScanline(&out[outindex + 1], &in[inindex], prevline, linebytes, bytewidth, 0);
+      out[outindex] = type; /*filter type byte*/
+      filterScanline(&out[outindex + 1], &in[inindex], prevline, linebytes, bytewidth, type);
       prevline = &in[inindex];
     }
-  }
-  else if(strategy == LFS_MINSUM)
-  {
+  } else if(strategy == LFS_MINSUM) {
     /*adaptive filtering*/
     size_t sum[5];
     unsigned char* attempt[5]; /*five filtering attempts, one for each filter type*/
     size_t smallest = 0;
     unsigned char type, bestType = 0;
 
-    for(type = 0; type != 5; ++type)
-    {
+    for(type = 0; type != 5; ++type) {
       attempt[type] = (unsigned char*)lodepng_malloc(linebytes);
       if(!attempt[type]) return 83; /*alloc fail*/
     }
 
-    if(!error)
-    {
-      for(y = 0; y != h; ++y)
-      {
+    if(!error) {
+      for(y = 0; y != h; ++y) {
         /*try the 5 filter types*/
-        for(type = 0; type != 5; ++type)
-        {
+        for(type = 0; type != 5; ++type) {
           filterScanline(attempt[type], &in[y * linebytes], prevline, linebytes, bytewidth, type);
 
           /*calculate the sum of the result*/
           sum[type] = 0;
-          if(type == 0)
-          {
+          if(type == 0) {
             for(x = 0; x != linebytes; ++x) sum[type] += (unsigned char)(attempt[type][x]);
-          }
-          else
-          {
-            for(x = 0; x != linebytes; ++x)
-            {
+          } else {
+            for(x = 0; x != linebytes; ++x) {
               /*For differences, each byte should be treated as signed, values above 127 are negative
               (converted to signed char). Filtertype 0 isn't a difference though, so use unsigned there.
               This means filtertype 0 is almost never chosen, but that is justified.*/
@@ -5272,8 +5396,7 @@ static unsigned filter(unsigned char* out, const unsigned char* in, unsigned w,
           }
 
           /*check if this is smallest sum (or if type == 0 it's the first case so always store the values)*/
-          if(type == 0 || sum[type] < smallest)
-          {
+          if(type == 0 || sum[type] < smallest) {
             bestType = type;
             smallest = sum[type];
           }
@@ -5288,41 +5411,33 @@ static unsigned filter(unsigned char* out, const unsigned char* in, unsigned w,
     }
 
     for(type = 0; type != 5; ++type) lodepng_free(attempt[type]);
-  }
-  else if(strategy == LFS_ENTROPY)
-  {
-    float sum[5];
+  } else if(strategy == LFS_ENTROPY) {
+    size_t sum[5];
     unsigned char* attempt[5]; /*five filtering attempts, one for each filter type*/
-    float smallest = 0;
+    size_t bestSum = 0;
     unsigned type, bestType = 0;
     unsigned count[256];
 
-    for(type = 0; type != 5; ++type)
-    {
+    for(type = 0; type != 5; ++type) {
       attempt[type] = (unsigned char*)lodepng_malloc(linebytes);
       if(!attempt[type]) return 83; /*alloc fail*/
     }
 
-    for(y = 0; y != h; ++y)
-    {
+    for(y = 0; y != h; ++y) {
       /*try the 5 filter types*/
-      for(type = 0; type != 5; ++type)
-      {
+      for(type = 0; type != 5; ++type) {
         filterScanline(attempt[type], &in[y * linebytes], prevline, linebytes, bytewidth, type);
         for(x = 0; x != 256; ++x) count[x] = 0;
         for(x = 0; x != linebytes; ++x) ++count[attempt[type][x]];
         ++count[type]; /*the filter type itself is part of the scanline*/
         sum[type] = 0;
-        for(x = 0; x != 256; ++x)
-        {
-          float p = count[x] / (float)(linebytes + 1);
-          sum[type] += count[x] == 0 ? 0 : flog2(1 / p) * p;
+        for(x = 0; x != 256; ++x) {
+          sum[type] += count[x] == 0 ? 0 : ilog2(count[x]) * count[x];
         }
         /*check if this is smallest sum (or if type == 0 it's the first case so always store the values)*/
-        if(type == 0 || sum[type] < smallest)
-        {
+        if(type == 0 || sum[type] > bestSum) {
           bestType = type;
-          smallest = sum[type];
+          bestSum = sum[type];
         }
       }
 
@@ -5334,11 +5449,8 @@ static unsigned filter(unsigned char* out, const unsigned char* in, unsigned w,
     }
 
     for(type = 0; type != 5; ++type) lodepng_free(attempt[type]);
-  }
-  else if(strategy == LFS_PREDEFINED)
-  {
-    for(y = 0; y != h; ++y)
-    {
+  } else if(strategy == LFS_PREDEFINED) {
+    for(y = 0; y != h; ++y) {
       size_t outindex = (1 + linebytes) * y; /*the extra filterbyte added to each row*/
       size_t inindex = linebytes * y;
       unsigned char type = settings->predefined_filters[y];
@@ -5346,9 +5458,7 @@ static unsigned filter(unsigned char* out, const unsigned char* in, unsigned w,
       filterScanline(&out[outindex + 1], &in[inindex], prevline, linebytes, bytewidth, type);
       prevline = &in[inindex];
     }
-  }
-  else if(strategy == LFS_BRUTE_FORCE)
-  {
+  } else if(strategy == LFS_BRUTE_FORCE) {
     /*brute force filter chooser.
     deflate the scanline after every filter attempt to see which one deflates best.
     This is very slow and gives only slightly smaller, sometimes even larger, result*/
@@ -5367,16 +5477,13 @@ static unsigned filter(unsigned char* out, const unsigned char* in, unsigned w,
     images only, so disable it*/
     zlibsettings.custom_zlib = 0;
     zlibsettings.custom_deflate = 0;
-    for(type = 0; type != 5; ++type)
-    {
+    for(type = 0; type != 5; ++type) {
       attempt[type] = (unsigned char*)lodepng_malloc(linebytes);
       if(!attempt[type]) return 83; /*alloc fail*/
     }
-    for(y = 0; y != h; ++y) /*try the 5 filter types*/
-    {
-      for(type = 0; type != 5; ++type)
-      {
-        unsigned testsize = linebytes;
+    for(y = 0; y != h; ++y) /*try the 5 filter types*/ {
+      for(type = 0; type != 5; ++type) {
+        unsigned testsize = (unsigned)linebytes;
         /*if(testsize > 8) testsize /= 8;*/ /*it already works good enough by testing a part of the row*/
 
         filterScanline(attempt[type], &in[y * linebytes], prevline, linebytes, bytewidth, type);
@@ -5385,8 +5492,7 @@ static unsigned filter(unsigned char* out, const unsigned char* in, unsigned w,
         zlib_compress(&dummy, &size[type], attempt[type], testsize, &zlibsettings);
         lodepng_free(dummy);
         /*check if this is smallest size (or if type == 0 it's the first case so always store the values)*/
-        if(type == 0 || size[type] < smallest)
-        {
+        if(type == 0 || size[type] < smallest) {
           bestType = type;
           smallest = size[type];
         }
@@ -5403,18 +5509,15 @@ static unsigned filter(unsigned char* out, const unsigned char* in, unsigned w,
 }
 
 static void addPaddingBits(unsigned char* out, const unsigned char* in,
-                           size_t olinebits, size_t ilinebits, unsigned h)
-{
+                           size_t olinebits, size_t ilinebits, unsigned h) {
   /*The opposite of the removePaddingBits function
   olinebits must be >= ilinebits*/
   unsigned y;
   size_t diff = olinebits - ilinebits;
   size_t obp = 0, ibp = 0; /*bit pointers*/
-  for(y = 0; y != h; ++y)
-  {
+  for(y = 0; y != h; ++y) {
     size_t x;
-    for(x = 0; x < ilinebits; ++x)
-    {
+    for(x = 0; x < ilinebits; ++x) {
       unsigned char bit = readBitFromReversedStream(&ibp, in);
       setBitOfReversedStream(&obp, out, bit);
     }
@@ -5435,47 +5538,37 @@ in has the following size in bits: w * h * bpp.
 out is possibly bigger due to padding bits between reduced images
 NOTE: comments about padding bits are only relevant if bpp < 8
 */
-static void Adam7_interlace(unsigned char* out, const unsigned char* in, unsigned w, unsigned h, unsigned bpp)
-{
+static void Adam7_interlace(unsigned char* out, const unsigned char* in, unsigned w, unsigned h, unsigned bpp) {
   unsigned passw[7], passh[7];
   size_t filter_passstart[8], padded_passstart[8], passstart[8];
   unsigned i;
 
   Adam7_getpassvalues(passw, passh, filter_passstart, padded_passstart, passstart, w, h, bpp);
 
-  if(bpp >= 8)
-  {
-    for(i = 0; i != 7; ++i)
-    {
+  if(bpp >= 8) {
+    for(i = 0; i != 7; ++i) {
       unsigned x, y, b;
-      size_t bytewidth = bpp / 8;
+      size_t bytewidth = bpp / 8u;
       for(y = 0; y < passh[i]; ++y)
-      for(x = 0; x < passw[i]; ++x)
-      {
+      for(x = 0; x < passw[i]; ++x) {
         size_t pixelinstart = ((ADAM7_IY[i] + y * ADAM7_DY[i]) * w + ADAM7_IX[i] + x * ADAM7_DX[i]) * bytewidth;
         size_t pixeloutstart = passstart[i] + (y * passw[i] + x) * bytewidth;
-        for(b = 0; b < bytewidth; ++b)
-        {
+        for(b = 0; b < bytewidth; ++b) {
           out[pixeloutstart + b] = in[pixelinstart + b];
         }
       }
     }
-  }
-  else /*bpp < 8: Adam7 with pixels < 8 bit is a bit trickier: with bit pointers*/
-  {
-    for(i = 0; i != 7; ++i)
-    {
+  } else /*bpp < 8: Adam7 with pixels < 8 bit is a bit trickier: with bit pointers*/ {
+    for(i = 0; i != 7; ++i) {
       unsigned x, y, b;
       unsigned ilinebits = bpp * passw[i];
       unsigned olinebits = bpp * w;
       size_t obp, ibp; /*bit pointers (for out and in buffer)*/
       for(y = 0; y < passh[i]; ++y)
-      for(x = 0; x < passw[i]; ++x)
-      {
+      for(x = 0; x < passw[i]; ++x) {
         ibp = (ADAM7_IY[i] + y * ADAM7_DY[i]) * olinebits + (ADAM7_IX[i] + x * ADAM7_DX[i]) * bpp;
         obp = (8 * passstart[i]) + (y * ilinebits + x * bpp);
-        for(b = 0; b < bpp; ++b)
-        {
+        for(b = 0; b < bpp; ++b) {
           unsigned char bit = readBitFromReversedStream(&ibp, in);
           setBitOfReversedStream(&obp, out, bit);
         }
@@ -5488,45 +5581,36 @@ static void Adam7_interlace(unsigned char* out, const unsigned char* in, unsigne
 return value is error**/
 static unsigned preProcessScanlines(unsigned char** out, size_t* outsize, const unsigned char* in,
                                     unsigned w, unsigned h,
-                                    const LodePNGInfo* info_png, const LodePNGEncoderSettings* settings)
-{
+                                    const LodePNGInfo* info_png, const LodePNGEncoderSettings* settings) {
   /*
   This function converts the pure 2D image with the PNG's colortype, into filtered-padded-interlaced data. Steps:
-  *) if no Adam7: 1) add padding bits (= posible extra bits per scanline if bpp < 8) 2) filter
+  *) if no Adam7: 1) add padding bits (= possible extra bits per scanline if bpp < 8) 2) filter
   *) if adam7: 1) Adam7_interlace 2) 7x add padding bits 3) 7x filter
   */
   unsigned bpp = lodepng_get_bpp(&info_png->color);
   unsigned error = 0;
 
-  if(info_png->interlace_method == 0)
-  {
-    *outsize = h + (h * ((w * bpp + 7) / 8)); /*image size plus an extra byte per scanline + possible padding bits*/
+  if(info_png->interlace_method == 0) {
+    *outsize = h + (h * ((w * bpp + 7u) / 8u)); /*image size plus an extra byte per scanline + possible padding bits*/
     *out = (unsigned char*)lodepng_malloc(*outsize);
     if(!(*out) && (*outsize)) error = 83; /*alloc fail*/
 
-    if(!error)
-    {
+    if(!error) {
       /*non multiple of 8 bits per scanline, padding bits needed per scanline*/
-      if(bpp < 8 && w * bpp != ((w * bpp + 7) / 8) * 8)
-      {
-        unsigned char* padded = (unsigned char*)lodepng_malloc(h * ((w * bpp + 7) / 8));
+      if(bpp < 8 && w * bpp != ((w * bpp + 7u) / 8u) * 8u) {
+        unsigned char* padded = (unsigned char*)lodepng_malloc(h * ((w * bpp + 7u) / 8u));
         if(!padded) error = 83; /*alloc fail*/
-        if(!error)
-        {
-          addPaddingBits(padded, in, ((w * bpp + 7) / 8) * 8, w * bpp, h);
+        if(!error) {
+          addPaddingBits(padded, in, ((w * bpp + 7u) / 8u) * 8u, w * bpp, h);
           error = filter(*out, padded, w, h, &info_png->color, settings);
         }
         lodepng_free(padded);
-      }
-      else
-      {
+      } else {
         /*we can immediately filter into the out buffer, no other steps needed*/
         error = filter(*out, in, w, h, &info_png->color, settings);
       }
     }
-  }
-  else /*interlace_method is 1 (Adam7)*/
-  {
+  } else /*interlace_method is 1 (Adam7)*/ {
     unsigned passw[7], passh[7];
     size_t filter_passstart[8], padded_passstart[8], passstart[8];
     unsigned char* adam7;
@@ -5540,25 +5624,20 @@ static unsigned preProcessScanlines(unsigned char** out, size_t* outsize, const
     adam7 = (unsigned char*)lodepng_malloc(passstart[7]);
     if(!adam7 && passstart[7]) error = 83; /*alloc fail*/
 
-    if(!error)
-    {
+    if(!error) {
       unsigned i;
 
       Adam7_interlace(adam7, in, w, h, bpp);
-      for(i = 0; i != 7; ++i)
-      {
-        if(bpp < 8)
-        {
+      for(i = 0; i != 7; ++i) {
+        if(bpp < 8) {
           unsigned char* padded = (unsigned char*)lodepng_malloc(padded_passstart[i + 1] - padded_passstart[i]);
           if(!padded) ERROR_BREAK(83); /*alloc fail*/
           addPaddingBits(padded, &adam7[passstart[i]],
-                         ((passw[i] * bpp + 7) / 8) * 8, passw[i] * bpp, passh[i]);
+                         ((passw[i] * bpp + 7u) / 8u) * 8u, passw[i] * bpp, passh[i]);
           error = filter(&(*out)[filter_passstart[i]], padded,
                          passw[i], passh[i], &info_png->color, settings);
           lodepng_free(padded);
-        }
-        else
-        {
+        } else {
           error = filter(&(*out)[filter_passstart[i]], &adam7[padded_passstart[i]],
                          passw[i], passh[i], &info_png->color, settings);
         }
@@ -5579,15 +5658,12 @@ returns 0 if the palette is opaque,
 returns 1 if the palette has a single color with alpha 0 ==> color key
 returns 2 if the palette is semi-translucent.
 */
-static unsigned getPaletteTranslucency(const unsigned char* palette, size_t palettesize)
-{
+static unsigned getPaletteTranslucency(const unsigned char* palette, size_t palettesize) {
   size_t i;
   unsigned key = 0;
   unsigned r = 0, g = 0, b = 0; /*the value of the color with alpha 0, so long as color keying is possible*/
-  for(i = 0; i != palettesize; ++i)
-  {
-    if(!key && palette[4 * i + 3] == 0)
-    {
+  for(i = 0; i != palettesize; ++i) {
+    if(!key && palette[4 * i + 3] == 0) {
       r = palette[4 * i + 0]; g = palette[4 * i + 1]; b = palette[4 * i + 2];
       key = 1;
       i = (size_t)(-1); /*restart from beginning, to detect earlier opaque colors with key's value*/
@@ -5600,82 +5676,147 @@ static unsigned getPaletteTranslucency(const unsigned char* palette, size_t pale
 }
 
 #ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS
-static unsigned addUnknownChunks(ucvector* out, unsigned char* data, size_t datasize)
-{
+static unsigned addUnknownChunks(ucvector* out, unsigned char* data, size_t datasize) {
   unsigned char* inchunk = data;
-  while((size_t)(inchunk - data) < datasize)
-  {
+  while((size_t)(inchunk - data) < datasize) {
     CERROR_TRY_RETURN(lodepng_chunk_append(&out->data, &out->size, inchunk));
     out->allocsize = out->size; /*fix the allocsize again*/
     inchunk = lodepng_chunk_next(inchunk);
   }
   return 0;
 }
+
+static unsigned isGrayICCProfile(const unsigned char* profile, unsigned size) {
+  /*
+  It is a gray profile if bytes 16-19 are "GRAY", rgb profile if bytes 16-19
+  are "RGB ". We do not perform any full parsing of the ICC profile here, other
+  than check those 4 bytes to grayscale profile. Other than that, validity of
+  the profile is not checked. This is needed only because the PNG specification
+  requires using a non-gray color model if there is an ICC profile with "RGB "
+  (sadly limiting compression opportunities if the input data is grayscale RGB
+  data), and requires using a gray color model if it is "GRAY".
+  */
+  if(size < 20) return 0;
+  return profile[16] == 'G' &&  profile[17] == 'R' &&  profile[18] == 'A' &&  profile[19] == 'Y';
+}
+
+static unsigned isRGBICCProfile(const unsigned char* profile, unsigned size) {
+  /* See comment in isGrayICCProfile*/
+  if(size < 20) return 0;
+  return profile[16] == 'R' &&  profile[17] == 'G' &&  profile[18] == 'B' &&  profile[19] == ' ';
+}
 #endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/
 
 unsigned lodepng_encode(unsigned char** out, size_t* outsize,
                         const unsigned char* image, unsigned w, unsigned h,
-                        LodePNGState* state)
-{
-  LodePNGInfo info;
-  ucvector outv;
+                        LodePNGState* state) {
   unsigned char* data = 0; /*uncompressed version of the IDAT chunk data*/
   size_t datasize = 0;
+  ucvector outv;
+  LodePNGInfo info;
+  const LodePNGInfo* info_png = &state->info_png;
+
+  ucvector_init(&outv);
+  lodepng_info_init(&info);
 
   /*provide some proper output values if error will happen*/
   *out = 0;
   *outsize = 0;
   state->error = 0;
 
-  lodepng_info_init(&info);
-  lodepng_info_copy(&info, &state->info_png);
-
-  if((info.color.colortype == LCT_PALETTE || state->encoder.force_palette)
-      && (info.color.palettesize == 0 || info.color.palettesize > 256))
-  {
+  /*check input values validity*/
+  if((info_png->color.colortype == LCT_PALETTE || state->encoder.force_palette)
+      && (info_png->color.palettesize == 0 || info_png->color.palettesize > 256)) {
     state->error = 68; /*invalid palette size, it is only allowed to be 1-256*/
-    return state->error;
+    goto cleanup;
   }
-
-  if(state->encoder.auto_convert)
-  {
-    state->error = lodepng_auto_choose_color(&info.color, image, w, h, &state->info_raw);
+  if(state->encoder.zlibsettings.btype > 2) {
+    state->error = 61; /*error: nonexistent btype*/
+    goto cleanup;
   }
-  if(state->error) return state->error;
-
-  if(state->encoder.zlibsettings.btype > 2)
-  {
-    CERROR_RETURN_ERROR(state->error, 61); /*error: unexisting btype*/
-  }
-  if(state->info_png.interlace_method > 1)
-  {
-    CERROR_RETURN_ERROR(state->error, 71); /*error: unexisting interlace mode*/
+  if(info_png->interlace_method > 1) {
+    state->error = 71; /*error: nonexistent interlace mode*/
+    goto cleanup;
   }
-
-  state->error = checkColorValidity(info.color.colortype, info.color.bitdepth);
-  if(state->error) return state->error; /*error: unexisting color type given*/
+  state->error = checkColorValidity(info_png->color.colortype, info_png->color.bitdepth);
+  if(state->error) goto cleanup; /*error: nonexistent color type given*/
   state->error = checkColorValidity(state->info_raw.colortype, state->info_raw.bitdepth);
-  if(state->error) return state->error; /*error: unexisting color type given*/
+  if(state->error) goto cleanup; /*error: nonexistent color type given*/
 
-  if(!lodepng_color_mode_equal(&state->info_raw, &info.color))
-  {
+  /* color convert and compute scanline filter types */
+  lodepng_info_copy(&info, &state->info_png);
+  if(state->encoder.auto_convert) {
+    LodePNGColorStats stats;
+    lodepng_color_stats_init(&stats);
+#ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS
+    if(info_png->iccp_defined &&
+        isGrayICCProfile(info_png->iccp_profile, info_png->iccp_profile_size)) {
+      /*the PNG specification does not allow to use palette with a GRAY ICC profile, even
+      if the palette has only gray colors, so disallow it.*/
+      stats.allow_palette = 0;
+    }
+    if(info_png->iccp_defined &&
+        isRGBICCProfile(info_png->iccp_profile, info_png->iccp_profile_size)) {
+      /*the PNG specification does not allow to use grayscale color with RGB ICC profile, so disallow gray.*/
+      stats.allow_greyscale = 0;
+    }
+#endif /* LODEPNG_COMPILE_ANCILLARY_CHUNKS */
+    lodepng_compute_color_stats(&stats, image, w, h, &state->info_raw);
+#ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS
+    if(info_png->background_defined) {
+      /*the background chunk's color must be taken into account as well*/
+      unsigned r = 0, g = 0, b = 0;
+      LodePNGColorMode mode16 = lodepng_color_mode_make(LCT_RGB, 16);
+      lodepng_convert_rgb(&r, &g, &b, info_png->background_r, info_png->background_g, info_png->background_b, &mode16, &info_png->color);
+      lodepng_color_stats_add(&stats, r, g, b, 65535);
+    }
+#endif /* LODEPNG_COMPILE_ANCILLARY_CHUNKS */
+    state->error = auto_choose_color(&info.color, &state->info_raw, &stats);
+    if(state->error) goto cleanup;
+#ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS
+    /*also convert the background chunk*/
+    if(info_png->background_defined) {
+      if(lodepng_convert_rgb(&info.background_r, &info.background_g, &info.background_b,
+          info_png->background_r, info_png->background_g, info_png->background_b, &info.color, &info_png->color)) {
+        state->error = 104;
+        goto cleanup;
+      }
+    }
+#endif /* LODEPNG_COMPILE_ANCILLARY_CHUNKS */
+  }
+#ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS
+  if(info_png->iccp_defined) {
+    unsigned gray_icc = isGrayICCProfile(info_png->iccp_profile, info_png->iccp_profile_size);
+    unsigned rgb_icc = isRGBICCProfile(info_png->iccp_profile, info_png->iccp_profile_size);
+    unsigned gray_png = info.color.colortype == LCT_GREY || info.color.colortype == LCT_GREY_ALPHA;
+    if(!gray_icc && !rgb_icc) {
+      state->error = 100; /* Disallowed profile color type for PNG */
+      goto cleanup;
+    }
+    if(gray_icc != gray_png) {
+      /*Not allowed to use RGB/RGBA/palette with GRAY ICC profile or vice versa,
+      or in case of auto_convert, it wasn't possible to find appropriate model*/
+      state->error = state->encoder.auto_convert ? 102 : 101;
+      goto cleanup;
+    }
+  }
+#endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/
+  if(!lodepng_color_mode_equal(&state->info_raw, &info.color)) {
     unsigned char* converted;
-    size_t size = (w * h * lodepng_get_bpp(&info.color) + 7) / 8;
+    size_t size = ((size_t)w * (size_t)h * (size_t)lodepng_get_bpp(&info.color) + 7u) / 8u;
 
     converted = (unsigned char*)lodepng_malloc(size);
     if(!converted && size) state->error = 83; /*alloc fail*/
-    if(!state->error)
-    {
+    if(!state->error) {
       state->error = lodepng_convert(converted, image, &info.color, &state->info_raw, w, h);
     }
     if(!state->error) preProcessScanlines(&data, &datasize, converted, w, h, &info, &state->encoder);
     lodepng_free(converted);
+    if(state->error) goto cleanup;
   }
   else preProcessScanlines(&data, &datasize, image, w, h, &info, &state->encoder);
 
-  ucvector_init(&outv);
-  while(!state->error) /*while only executed once, to break on error*/
-  {
+  /* output all PNG chunks */ {
 #ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS
     size_t i;
 #endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/
@@ -5685,100 +5826,92 @@ unsigned lodepng_encode(unsigned char** out, size_t* outsize,
     addChunk_IHDR(&outv, w, h, info.color.colortype, info.color.bitdepth, info.interlace_method);
 #ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS
     /*unknown chunks between IHDR and PLTE*/
-    if(info.unknown_chunks_data[0])
-    {
+    if(info.unknown_chunks_data[0]) {
       state->error = addUnknownChunks(&outv, info.unknown_chunks_data[0], info.unknown_chunks_size[0]);
-      if(state->error) break;
+      if(state->error) goto cleanup;
     }
+    /*color profile chunks must come before PLTE */
+    if(info.iccp_defined) addChunk_iCCP(&outv, &info, &state->encoder.zlibsettings);
+    if(info.srgb_defined) addChunk_sRGB(&outv, &info);
+    if(info.gama_defined) addChunk_gAMA(&outv, &info);
+    if(info.chrm_defined) addChunk_cHRM(&outv, &info);
 #endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/
     /*PLTE*/
-    if(info.color.colortype == LCT_PALETTE)
-    {
+    if(info.color.colortype == LCT_PALETTE) {
       addChunk_PLTE(&outv, &info.color);
     }
-    if(state->encoder.force_palette && (info.color.colortype == LCT_RGB || info.color.colortype == LCT_RGBA))
-    {
+    if(state->encoder.force_palette && (info.color.colortype == LCT_RGB || info.color.colortype == LCT_RGBA)) {
       addChunk_PLTE(&outv, &info.color);
     }
     /*tRNS*/
-    if(info.color.colortype == LCT_PALETTE && getPaletteTranslucency(info.color.palette, info.color.palettesize) != 0)
-    {
+    if(info.color.colortype == LCT_PALETTE && getPaletteTranslucency(info.color.palette, info.color.palettesize) != 0) {
       addChunk_tRNS(&outv, &info.color);
     }
-    if((info.color.colortype == LCT_GREY || info.color.colortype == LCT_RGB) && info.color.key_defined)
-    {
+    if((info.color.colortype == LCT_GREY || info.color.colortype == LCT_RGB) && info.color.key_defined) {
       addChunk_tRNS(&outv, &info.color);
     }
 #ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS
     /*bKGD (must come between PLTE and the IDAt chunks*/
-    if(info.background_defined) addChunk_bKGD(&outv, &info);
+    if(info.background_defined) {
+      state->error = addChunk_bKGD(&outv, &info);
+      if(state->error) goto cleanup;
+    }
     /*pHYs (must come before the IDAT chunks)*/
     if(info.phys_defined) addChunk_pHYs(&outv, &info);
 
     /*unknown chunks between PLTE and IDAT*/
-    if(info.unknown_chunks_data[1])
-    {
+    if(info.unknown_chunks_data[1]) {
       state->error = addUnknownChunks(&outv, info.unknown_chunks_data[1], info.unknown_chunks_size[1]);
-      if(state->error) break;
+      if(state->error) goto cleanup;
     }
 #endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/
     /*IDAT (multiple IDAT chunks must be consecutive)*/
     state->error = addChunk_IDAT(&outv, data, datasize, &state->encoder.zlibsettings);
-    if(state->error) break;
+    if(state->error) goto cleanup;
 #ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS
     /*tIME*/
     if(info.time_defined) addChunk_tIME(&outv, &info.time);
     /*tEXt and/or zTXt*/
-    for(i = 0; i != info.text_num; ++i)
-    {
-      if(strlen(info.text_keys[i]) > 79)
-      {
+    for(i = 0; i != info.text_num; ++i) {
+      if(lodepng_strlen(info.text_keys[i]) > 79) {
         state->error = 66; /*text chunk too large*/
-        break;
+        goto cleanup;
       }
-      if(strlen(info.text_keys[i]) < 1)
-      {
+      if(lodepng_strlen(info.text_keys[i]) < 1) {
         state->error = 67; /*text chunk too small*/
-        break;
+        goto cleanup;
       }
-      if(state->encoder.text_compression)
-      {
+      if(state->encoder.text_compression) {
         addChunk_zTXt(&outv, info.text_keys[i], info.text_strings[i], &state->encoder.zlibsettings);
-      }
-      else
-      {
+      } else {
         addChunk_tEXt(&outv, info.text_keys[i], info.text_strings[i]);
       }
     }
     /*LodePNG version id in text chunk*/
-    if(state->encoder.add_id)
-    {
-      unsigned alread_added_id_text = 0;
-      for(i = 0; i != info.text_num; ++i)
-      {
-        if(!strcmp(info.text_keys[i], "LodePNG"))
-        {
-          alread_added_id_text = 1;
+    if(state->encoder.add_id) {
+      unsigned already_added_id_text = 0;
+      for(i = 0; i != info.text_num; ++i) {
+        const char* k = info.text_keys[i];
+        /* Could use strcmp, but we're not calling or reimplementing this C library function for this use only */
+        if(k[0] == 'L' && k[1] == 'o' && k[2] == 'd' && k[3] == 'e' &&
+           k[4] == 'P' && k[5] == 'N' && k[6] == 'G' && k[7] == '\0') {
+          already_added_id_text = 1;
           break;
         }
       }
-      if(alread_added_id_text == 0)
-      {
+      if(already_added_id_text == 0) {
         addChunk_tEXt(&outv, "LodePNG", LODEPNG_VERSION_STRING); /*it's shorter as tEXt than as zTXt chunk*/
       }
     }
     /*iTXt*/
-    for(i = 0; i != info.itext_num; ++i)
-    {
-      if(strlen(info.itext_keys[i]) > 79)
-      {
+    for(i = 0; i != info.itext_num; ++i) {
+      if(lodepng_strlen(info.itext_keys[i]) > 79) {
         state->error = 66; /*text chunk too large*/
-        break;
+        goto cleanup;
       }
-      if(strlen(info.itext_keys[i]) < 1)
-      {
+      if(lodepng_strlen(info.itext_keys[i]) < 1) {
         state->error = 67; /*text chunk too small*/
-        break;
+        goto cleanup;
       }
       addChunk_iTXt(&outv, state->encoder.text_compression,
                     info.itext_keys[i], info.itext_langtags[i], info.itext_transkeys[i], info.itext_strings[i],
@@ -5786,19 +5919,18 @@ unsigned lodepng_encode(unsigned char** out, size_t* outsize,
     }
 
     /*unknown chunks between IDAT and IEND*/
-    if(info.unknown_chunks_data[2])
-    {
+    if(info.unknown_chunks_data[2]) {
       state->error = addUnknownChunks(&outv, info.unknown_chunks_data[2], info.unknown_chunks_size[2]);
-      if(state->error) break;
+      if(state->error) goto cleanup;
     }
 #endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/
     addChunk_IEND(&outv);
-
-    break; /*this isn't really a while loop; no error happened so break out now!*/
   }
 
+cleanup:
   lodepng_info_cleanup(&info);
   lodepng_free(data);
+
   /*instead of cleaning the vector up, give it to the output*/
   *out = outv.data;
   *outsize = outv.size;
@@ -5807,8 +5939,7 @@ unsigned lodepng_encode(unsigned char** out, size_t* outsize,
 }
 
 unsigned lodepng_encode_memory(unsigned char** out, size_t* outsize, const unsigned char* image,
-                               unsigned w, unsigned h, LodePNGColorType colortype, unsigned bitdepth)
-{
+                               unsigned w, unsigned h, LodePNGColorType colortype, unsigned bitdepth) {
   unsigned error;
   LodePNGState state;
   lodepng_state_init(&state);
@@ -5822,20 +5953,17 @@ unsigned lodepng_encode_memory(unsigned char** out, size_t* outsize, const unsig
   return error;
 }
 
-unsigned lodepng_encode32(unsigned char** out, size_t* outsize, const unsigned char* image, unsigned w, unsigned h)
-{
+unsigned lodepng_encode32(unsigned char** out, size_t* outsize, const unsigned char* image, unsigned w, unsigned h) {
   return lodepng_encode_memory(out, outsize, image, w, h, LCT_RGBA, 8);
 }
 
-unsigned lodepng_encode24(unsigned char** out, size_t* outsize, const unsigned char* image, unsigned w, unsigned h)
-{
+unsigned lodepng_encode24(unsigned char** out, size_t* outsize, const unsigned char* image, unsigned w, unsigned h) {
   return lodepng_encode_memory(out, outsize, image, w, h, LCT_RGB, 8);
 }
 
 #ifdef LODEPNG_COMPILE_DISK
 unsigned lodepng_encode_file(const char* filename, const unsigned char* image, unsigned w, unsigned h,
-                             LodePNGColorType colortype, unsigned bitdepth)
-{
+                             LodePNGColorType colortype, unsigned bitdepth) {
   unsigned char* buffer;
   size_t buffersize;
   unsigned error = lodepng_encode_memory(&buffer, &buffersize, image, w, h, colortype, bitdepth);
@@ -5844,19 +5972,16 @@ unsigned lodepng_encode_file(const char* filename, const unsigned char* image, u
   return error;
 }
 
-unsigned lodepng_encode32_file(const char* filename, const unsigned char* image, unsigned w, unsigned h)
-{
+unsigned lodepng_encode32_file(const char* filename, const unsigned char* image, unsigned w, unsigned h) {
   return lodepng_encode_file(filename, image, w, h, LCT_RGBA, 8);
 }
 
-unsigned lodepng_encode24_file(const char* filename, const unsigned char* image, unsigned w, unsigned h)
-{
+unsigned lodepng_encode24_file(const char* filename, const unsigned char* image, unsigned w, unsigned h) {
   return lodepng_encode_file(filename, image, w, h, LCT_RGB, 8);
 }
 #endif /*LODEPNG_COMPILE_DISK*/
 
-void lodepng_encoder_settings_init(LodePNGEncoderSettings* settings)
-{
+void lodepng_encoder_settings_init(LodePNGEncoderSettings* settings) {
   lodepng_compress_settings_init(&settings->zlibsettings);
   settings->filter_palette_zero = 1;
   settings->filter_strategy = LFS_MINSUM;
@@ -5877,10 +6002,8 @@ void lodepng_encoder_settings_init(LodePNGEncoderSettings* settings)
 This returns the description of a numerical error code in English. This is also
 the documentation of all the error codes.
 */
-const char* lodepng_error_text(unsigned code)
-{
-  switch(code)
-  {
+const char* lodepng_error_text(unsigned code) {
+  switch(code) {
     case 0: return "no error, everything went ok";
     case 1: return "nothing done yet"; /*the Encoder/Decoder has done nothing yet, error checking makes no sense yet*/
     case 10: return "end of input memory reached without huffman end code"; /*while huffman decoding*/
@@ -5888,16 +6011,17 @@ const char* lodepng_error_text(unsigned code)
     case 13: return "problem while processing dynamic deflate block";
     case 14: return "problem while processing dynamic deflate block";
     case 15: return "problem while processing dynamic deflate block";
-    case 16: return "unexisting code while processing dynamic deflate block";
+    case 16: return "nonexistent code while processing dynamic deflate block";
     case 17: return "end of out buffer memory reached while inflating";
     case 18: return "invalid distance code while inflating";
     case 19: return "end of out buffer memory reached while inflating";
     case 20: return "invalid deflate block BTYPE encountered while decoding";
     case 21: return "NLEN is not ones complement of LEN in a deflate block";
-     /*end of out buffer memory reached while inflating:
-     This can happen if the inflated deflate data is longer than the amount of bytes required to fill up
-     all the pixels of the image, given the color depth and image dimensions. Something that doesn't
-     happen in a normal, well encoded, PNG image.*/
+
+    /*end of out buffer memory reached while inflating:
+    This can happen if the inflated deflate data is longer than the amount of bytes required to fill up
+    all the pixels of the image, given the color depth and image dimensions. Something that doesn't
+    happen in a normal, well encoded, PNG image.*/
     case 22: return "end of out buffer memory reached while inflating";
     case 23: return "end of in buffer memory reached while inflating";
     case 24: return "invalid FCHECK in zlib header";
@@ -5915,13 +6039,13 @@ const char* lodepng_error_text(unsigned code)
     case 35: return "chunk length of a chunk is too large or the chunk too small";
     case 36: return "illegal PNG filter type encountered";
     case 37: return "illegal bit depth for this color type given";
-    case 38: return "the palette is too big"; /*more than 256 colors*/
-    case 39: return "more palette alpha values given in tRNS chunk than there are colors in the palette";
-    case 40: return "tRNS chunk has wrong size for greyscale image";
+    case 38: return "the palette is too small or too big"; /*0, or more than 256 colors*/
+    case 39: return "tRNS chunk before PLTE or has more entries than palette size";
+    case 40: return "tRNS chunk has wrong size for grayscale image";
     case 41: return "tRNS chunk has wrong size for RGB image";
     case 42: return "tRNS chunk appeared while it was not allowed for this color type";
     case 43: return "bKGD chunk has wrong size for palette image";
-    case 44: return "bKGD chunk has wrong size for greyscale image";
+    case 44: return "bKGD chunk has wrong size for grayscale image";
     case 45: return "bKGD chunk has wrong size for RGB image";
     case 48: return "empty input buffer given to decoder. Maybe caused by non-existing file?";
     case 49: return "jumped past memory while generating dynamic huffman tree";
@@ -5932,7 +6056,7 @@ const char* lodepng_error_text(unsigned code)
     case 54: return "repeat symbol in tree while there was no value symbol yet";
     /*jumped past tree while generating huffman tree, this could be when the
     tree will have more leaves than symbols after generating it out of the
-    given lenghts. They call this an oversubscribed dynamic bit lengths tree in zlib.*/
+    given lengths. They call this an oversubscribed dynamic bit lengths tree in zlib.*/
     case 55: return "jumped past tree while generating huffman tree";
     case 56: return "given output image colortype or bitdepth not supported for color conversion";
     case 57: return "invalid CRC encountered (checking CRC can be disabled)";
@@ -5940,17 +6064,18 @@ const char* lodepng_error_text(unsigned code)
     case 59: return "requested color conversion not supported";
     case 60: return "invalid window size given in the settings of the encoder (must be 0-32768)";
     case 61: return "invalid BTYPE given in the settings of the encoder (only 0, 1 and 2 are allowed)";
-    /*LodePNG leaves the choice of RGB to greyscale conversion formula to the user.*/
-    case 62: return "conversion from color to greyscale not supported";
-    case 63: return "length of a chunk too long, max allowed for PNG is 2147483647 bytes per chunk"; /*(2^31-1)*/
+    /*LodePNG leaves the choice of RGB to grayscale conversion formula to the user.*/
+    case 62: return "conversion from color to grayscale not supported";
+    /*(2^31-1)*/
+    case 63: return "length of a chunk too long, max allowed for PNG is 2147483647 bytes per chunk";
     /*this would result in the inability of a deflated block to ever contain an end code. It must be at least 1.*/
     case 64: return "the length of the END symbol 256 in the Huffman tree is 0";
     case 66: return "the length of a text chunk keyword given to the encoder is longer than the maximum of 79 bytes";
     case 67: return "the length of a text chunk keyword given to the encoder is smaller than the minimum of 1 byte";
     case 68: return "tried to encode a PLTE chunk with a palette that has less than 1 or more than 256 colors";
     case 69: return "unknown chunk type with 'critical' flag encountered by the decoder";
-    case 71: return "unexisting interlace mode given to encoder (must be 0 or 1)";
-    case 72: return "while decoding, unexisting compression method encountering in zTXt or iTXt chunk (it must be 0)";
+    case 71: return "nonexistent interlace mode given to encoder (must be 0 or 1)";
+    case 72: return "while decoding, nonexistent compression method encountering in zTXt or iTXt chunk (it must be 0)";
     case 73: return "invalid tIME chunk size";
     case 74: return "invalid pHYs chunk size";
     /*length could be wrong, or data chopped off*/
@@ -5961,7 +6086,7 @@ const char* lodepng_error_text(unsigned code)
     case 79: return "failed to open file for writing";
     case 80: return "tried creating a tree of 0 symbols";
     case 81: return "lazy matching at pos 0 is impossible";
-    case 82: return "color conversion to palette requested while a color isn't in palette";
+    case 82: return "color conversion to palette requested while a color isn't in palette, or index out of bounds";
     case 83: return "memory allocation failed";
     case 84: return "given image too small to contain all pixels to be encoded";
     case 86: return "impossible offset in lz77 encoding (internal bug)";
@@ -5971,9 +6096,20 @@ const char* lodepng_error_text(unsigned code)
     /*the windowsize in the LodePNGCompressSettings. Requiring POT(==> & instead of %) makes encoding 12% faster.*/
     case 90: return "windowsize must be a power of two";
     case 91: return "invalid decompressed idat size";
-    case 92: return "too many pixels, not supported";
+    case 92: return "integer overflow due to too many pixels";
     case 93: return "zero width or height is invalid";
     case 94: return "header chunk must have a size of 13 bytes";
+    case 95: return "integer overflow with combined idat chunk size";
+    case 96: return "invalid gAMA chunk size";
+    case 97: return "invalid cHRM chunk size";
+    case 98: return "invalid sRGB chunk size";
+    case 99: return "invalid sRGB rendering intent";
+    case 100: return "invalid ICC profile color type, the PNG specification only allows RGB or GRAY";
+    case 101: return "PNG specification does not allow RGB ICC profile on gray color types and vice versa";
+    case 102: return "not allowed to set grayscale ICC profile with colored pixels by PNG specification";
+    case 103: return "invalid palette index in bKGD chunk. Maybe it came before PLTE chunk?";
+    case 104: return "invalid bKGD color while encoding (e.g. palette index out of range)";
+    case 105: return "integer overflow of bitsize";
   }
   return "unknown error code";
 }
@@ -5986,12 +6122,10 @@ const char* lodepng_error_text(unsigned code)
 /* ////////////////////////////////////////////////////////////////////////// */
 
 #ifdef LODEPNG_COMPILE_CPP
-namespace lodepng
-{
+namespace lodepng {
 
 #ifdef LODEPNG_COMPILE_DISK
-unsigned load_file(std::vector<unsigned char>& buffer, const std::string& filename)
-{
+unsigned load_file(std::vector<unsigned char>& buffer, const std::string& filename) {
   long size = lodepng_filesize(filename.c_str());
   if(size < 0) return 78;
   buffer.resize((size_t)size);
@@ -5999,8 +6133,7 @@ unsigned load_file(std::vector<unsigned char>& buffer, const std::string& filena
 }
 
 /*write given buffer to the file, overwriting the file, it doesn't append to it.*/
-unsigned save_file(const std::vector<unsigned char>& buffer, const std::string& filename)
-{
+unsigned save_file(const std::vector<unsigned char>& buffer, const std::string& filename) {
   return lodepng_save_file(buffer.empty() ? 0 : &buffer[0], buffer.size(), filename.c_str());
 }
 #endif /* LODEPNG_COMPILE_DISK */
@@ -6008,13 +6141,11 @@ unsigned save_file(const std::vector<unsigned char>& buffer, const std::string&
 #ifdef LODEPNG_COMPILE_ZLIB
 #ifdef LODEPNG_COMPILE_DECODER
 unsigned decompress(std::vector<unsigned char>& out, const unsigned char* in, size_t insize,
-                    const LodePNGDecompressSettings& settings)
-{
+                    const LodePNGDecompressSettings& settings) {
   unsigned char* buffer = 0;
   size_t buffersize = 0;
   unsigned error = zlib_decompress(&buffer, &buffersize, in, insize, &settings);
-  if(buffer)
-  {
+  if(buffer) {
     out.insert(out.end(), &buffer[0], &buffer[buffersize]);
     lodepng_free(buffer);
   }
@@ -6022,21 +6153,18 @@ unsigned decompress(std::vector<unsigned char>& out, const unsigned char* in, si
 }
 
 unsigned decompress(std::vector<unsigned char>& out, const std::vector<unsigned char>& in,
-                    const LodePNGDecompressSettings& settings)
-{
+                    const LodePNGDecompressSettings& settings) {
   return decompress(out, in.empty() ? 0 : &in[0], in.size(), settings);
 }
 #endif /* LODEPNG_COMPILE_DECODER */
 
 #ifdef LODEPNG_COMPILE_ENCODER
 unsigned compress(std::vector<unsigned char>& out, const unsigned char* in, size_t insize,
-                  const LodePNGCompressSettings& settings)
-{
+                  const LodePNGCompressSettings& settings) {
   unsigned char* buffer = 0;
   size_t buffersize = 0;
   unsigned error = zlib_compress(&buffer, &buffersize, in, insize, &settings);
-  if(buffer)
-  {
+  if(buffer) {
     out.insert(out.end(), &buffer[0], &buffer[buffersize]);
     lodepng_free(buffer);
   }
@@ -6044,8 +6172,7 @@ unsigned compress(std::vector<unsigned char>& out, const unsigned char* in, size
 }
 
 unsigned compress(std::vector<unsigned char>& out, const std::vector<unsigned char>& in,
-                  const LodePNGCompressSettings& settings)
-{
+                  const LodePNGCompressSettings& settings) {
   return compress(out, in.empty() ? 0 : &in[0], in.size(), settings);
 }
 #endif /* LODEPNG_COMPILE_ENCODER */
@@ -6054,24 +6181,20 @@ unsigned compress(std::vector<unsigned char>& out, const std::vector<unsigned ch
 
 #ifdef LODEPNG_COMPILE_PNG
 
-State::State()
-{
+State::State() {
   lodepng_state_init(this);
 }
 
-State::State(const State& other)
-{
+State::State(const State& other) {
   lodepng_state_init(this);
   lodepng_state_copy(this, &other);
 }
 
-State::~State()
-{
+State::~State() {
   lodepng_state_cleanup(this);
 }
 
-State& State::operator=(const State& other)
-{
+State& State::operator=(const State& other) {
   lodepng_state_copy(this, &other);
   return *this;
 }
@@ -6079,12 +6202,10 @@ State& State::operator=(const State& other)
 #ifdef LODEPNG_COMPILE_DECODER
 
 unsigned decode(std::vector<unsigned char>& out, unsigned& w, unsigned& h, const unsigned char* in,
-                size_t insize, LodePNGColorType colortype, unsigned bitdepth)
-{
+                size_t insize, LodePNGColorType colortype, unsigned bitdepth) {
   unsigned char* buffer;
   unsigned error = lodepng_decode_memory(&buffer, &w, &h, in, insize, colortype, bitdepth);
-  if(buffer && !error)
-  {
+  if(buffer && !error) {
     State state;
     state.info_raw.colortype = colortype;
     state.info_raw.bitdepth = bitdepth;
@@ -6096,19 +6217,16 @@ unsigned decode(std::vector<unsigned char>& out, unsigned& w, unsigned& h, const
 }
 
 unsigned decode(std::vector<unsigned char>& out, unsigned& w, unsigned& h,
-                const std::vector<unsigned char>& in, LodePNGColorType colortype, unsigned bitdepth)
-{
+                const std::vector<unsigned char>& in, LodePNGColorType colortype, unsigned bitdepth) {
   return decode(out, w, h, in.empty() ? 0 : &in[0], (unsigned)in.size(), colortype, bitdepth);
 }
 
 unsigned decode(std::vector<unsigned char>& out, unsigned& w, unsigned& h,
                 State& state,
-                const unsigned char* in, size_t insize)
-{
+                const unsigned char* in, size_t insize) {
   unsigned char* buffer = NULL;
   unsigned error = lodepng_decode(&buffer, &w, &h, &state, in, insize);
-  if(buffer && !error)
-  {
+  if(buffer && !error) {
     size_t buffersize = lodepng_get_raw_size(w, h, &state.info_raw);
     out.insert(out.end(), &buffer[0], &buffer[buffersize]);
   }
@@ -6118,16 +6236,16 @@ unsigned decode(std::vector<unsigned char>& out, unsigned& w, unsigned& h,
 
 unsigned decode(std::vector<unsigned char>& out, unsigned& w, unsigned& h,
                 State& state,
-                const std::vector<unsigned char>& in)
-{
+                const std::vector<unsigned char>& in) {
   return decode(out, w, h, state, in.empty() ? 0 : &in[0], in.size());
 }
 
 #ifdef LODEPNG_COMPILE_DISK
 unsigned decode(std::vector<unsigned char>& out, unsigned& w, unsigned& h, const std::string& filename,
-                LodePNGColorType colortype, unsigned bitdepth)
-{
+                LodePNGColorType colortype, unsigned bitdepth) {
   std::vector<unsigned char> buffer;
+  /* safe output values in case error happens */
+  w = h = 0;
   unsigned error = load_file(buffer, filename);
   if(error) return error;
   return decode(out, w, h, buffer, colortype, bitdepth);
@@ -6137,13 +6255,11 @@ unsigned decode(std::vector<unsigned char>& out, unsigned& w, unsigned& h, const
 
 #ifdef LODEPNG_COMPILE_ENCODER
 unsigned encode(std::vector<unsigned char>& out, const unsigned char* in, unsigned w, unsigned h,
-                LodePNGColorType colortype, unsigned bitdepth)
-{
+                LodePNGColorType colortype, unsigned bitdepth) {
   unsigned char* buffer;
   size_t buffersize;
   unsigned error = lodepng_encode_memory(&buffer, &buffersize, in, w, h, colortype, bitdepth);
-  if(buffer)
-  {
+  if(buffer) {
     out.insert(out.end(), &buffer[0], &buffer[buffersize]);
     lodepng_free(buffer);
   }
@@ -6152,21 +6268,18 @@ unsigned encode(std::vector<unsigned char>& out, const unsigned char* in, unsign
 
 unsigned encode(std::vector<unsigned char>& out,
                 const std::vector<unsigned char>& in, unsigned w, unsigned h,
-                LodePNGColorType colortype, unsigned bitdepth)
-{
+                LodePNGColorType colortype, unsigned bitdepth) {
   if(lodepng_get_raw_size_lct(w, h, colortype, bitdepth) > in.size()) return 84;
   return encode(out, in.empty() ? 0 : &in[0], w, h, colortype, bitdepth);
 }
 
 unsigned encode(std::vector<unsigned char>& out,
                 const unsigned char* in, unsigned w, unsigned h,
-                State& state)
-{
+                State& state) {
   unsigned char* buffer;
   size_t buffersize;
   unsigned error = lodepng_encode(&buffer, &buffersize, in, w, h, &state);
-  if(buffer)
-  {
+  if(buffer) {
     out.insert(out.end(), &buffer[0], &buffer[buffersize]);
     lodepng_free(buffer);
   }
@@ -6175,8 +6288,7 @@ unsigned encode(std::vector<unsigned char>& out,
 
 unsigned encode(std::vector<unsigned char>& out,
                 const std::vector<unsigned char>& in, unsigned w, unsigned h,
-                State& state)
-{
+                State& state) {
   if(lodepng_get_raw_size(w, h, &state.info_raw) > in.size()) return 84;
   return encode(out, in.empty() ? 0 : &in[0], w, h, state);
 }
@@ -6184,8 +6296,7 @@ unsigned encode(std::vector<unsigned char>& out,
 #ifdef LODEPNG_COMPILE_DISK
 unsigned encode(const std::string& filename,
                 const unsigned char* in, unsigned w, unsigned h,
-                LodePNGColorType colortype, unsigned bitdepth)
-{
+                LodePNGColorType colortype, unsigned bitdepth) {
   std::vector<unsigned char> buffer;
   unsigned error = encode(buffer, in, w, h, colortype, bitdepth);
   if(!error) error = save_file(buffer, filename);
@@ -6194,8 +6305,7 @@ unsigned encode(const std::string& filename,
 
 unsigned encode(const std::string& filename,
                 const std::vector<unsigned char>& in, unsigned w, unsigned h,
-                LodePNGColorType colortype, unsigned bitdepth)
-{
+                LodePNGColorType colortype, unsigned bitdepth) {
   if(lodepng_get_raw_size_lct(w, h, colortype, bitdepth) > in.size()) return 84;
   return encode(filename, in.empty() ? 0 : &in[0], w, h, colortype, bitdepth);
 }
diff --git a/src/zopflipng/lodepng/lodepng.h b/src/zopflipng/lodepng/lodepng.h
index 33f1051..9f21210 100644
--- a/src/zopflipng/lodepng/lodepng.h
+++ b/src/zopflipng/lodepng/lodepng.h
@@ -1,7 +1,7 @@
 /*
-LodePNG version 20160409
+LodePNG version 20190914
 
-Copyright (c) 2005-2016 Lode Vandevenne
+Copyright (c) 2005-2019 Lode Vandevenne
 
 This software is provided 'as-is', without any express or implied
 warranty. In no event will the authors be held liable for any damages
@@ -44,36 +44,44 @@ the custom_zlib field of the compress and decompress settings*/
 #ifndef LODEPNG_NO_COMPILE_ZLIB
 #define LODEPNG_COMPILE_ZLIB
 #endif
+
 /*png encoder and png decoder*/
 #ifndef LODEPNG_NO_COMPILE_PNG
 #define LODEPNG_COMPILE_PNG
 #endif
+
 /*deflate&zlib decoder and png decoder*/
 #ifndef LODEPNG_NO_COMPILE_DECODER
 #define LODEPNG_COMPILE_DECODER
 #endif
+
 /*deflate&zlib encoder and png encoder*/
 #ifndef LODEPNG_NO_COMPILE_ENCODER
 #define LODEPNG_COMPILE_ENCODER
 #endif
+
 /*the optional built in harddisk file loading and saving functions*/
 #ifndef LODEPNG_NO_COMPILE_DISK
 #define LODEPNG_COMPILE_DISK
 #endif
+
 /*support for chunks other than IHDR, IDAT, PLTE, tRNS, IEND: ancillary and unknown chunks*/
 #ifndef LODEPNG_NO_COMPILE_ANCILLARY_CHUNKS
 #define LODEPNG_COMPILE_ANCILLARY_CHUNKS
 #endif
+
 /*ability to convert error numerical codes to English text string*/
 #ifndef LODEPNG_NO_COMPILE_ERROR_TEXT
 #define LODEPNG_COMPILE_ERROR_TEXT
 #endif
+
 /*Compile the default allocators (C's free, malloc and realloc). If you disable this,
 you can define the functions lodepng_free, lodepng_malloc and lodepng_realloc in your
 source files with custom allocators.*/
 #ifndef LODEPNG_NO_COMPILE_ALLOCATORS
 #define LODEPNG_COMPILE_ALLOCATORS
 #endif
+
 /*compile the C++ version (you can disable the C++ wrapper here even when compiling for C++)*/
 #ifdef __cplusplus
 #ifndef LODEPNG_NO_COMPILE_CPP
@@ -87,14 +95,19 @@ source files with custom allocators.*/
 #endif /*LODEPNG_COMPILE_CPP*/
 
 #ifdef LODEPNG_COMPILE_PNG
-/*The PNG color types (also used for raw).*/
-typedef enum LodePNGColorType
-{
-  LCT_GREY = 0, /*greyscale: 1,2,4,8,16 bit*/
+/*The PNG color types (also used for raw image).*/
+typedef enum LodePNGColorType {
+  LCT_GREY = 0, /*grayscale: 1,2,4,8,16 bit*/
   LCT_RGB = 2, /*RGB: 8,16 bit*/
   LCT_PALETTE = 3, /*palette: 1,2,4,8 bit*/
-  LCT_GREY_ALPHA = 4, /*greyscale with alpha: 8,16 bit*/
-  LCT_RGBA = 6 /*RGB with alpha: 8,16 bit*/
+  LCT_GREY_ALPHA = 4, /*grayscale with alpha: 8,16 bit*/
+  LCT_RGBA = 6, /*RGB with alpha: 8,16 bit*/
+  /*LCT_MAX_OCTET_VALUE lets the compiler allow this enum to represent any invalid
+  byte value from 0 to 255 that could be present in an invalid PNG file header. Do
+  not use, compare with or set the name LCT_MAX_OCTET_VALUE, instead either use
+  the valid color type names above, or numeric values like 1 or 7 when checking for
+  particular disallowed color type byte values, or cast to integer to print it.*/
+  LCT_MAX_OCTET_VALUE = 255
 } LodePNGColorType;
 
 #ifdef LODEPNG_COMPILE_DECODER
@@ -196,8 +209,7 @@ unsigned lodepng_encode24_file(const char* filename,
 
 
 #ifdef LODEPNG_COMPILE_CPP
-namespace lodepng
-{
+namespace lodepng {
 #ifdef LODEPNG_COMPILE_DECODER
 /*Same as lodepng_decode_memory, but decodes to an std::vector. The colortype
 is the format to output the pixels to. Default is RGBA 8-bit per channel.*/
@@ -253,17 +265,17 @@ const char* lodepng_error_text(unsigned code);
 #ifdef LODEPNG_COMPILE_DECODER
 /*Settings for zlib decompression*/
 typedef struct LodePNGDecompressSettings LodePNGDecompressSettings;
-struct LodePNGDecompressSettings
-{
+struct LodePNGDecompressSettings {
+  /* Check LodePNGDecoderSettings for more ignorable errors such as ignore_crc */
   unsigned ignore_adler32; /*if 1, continue and don't give an error message if the Adler32 checksum is corrupted*/
+  unsigned ignore_nlen; /*ignore complement of len checksum in uncompressed blocks*/
 
   /*use custom zlib decoder instead of built in one (default: null)*/
   unsigned (*custom_zlib)(unsigned char**, size_t*,
                           const unsigned char*, size_t,
                           const LodePNGDecompressSettings*);
   /*use custom deflate decoder instead of built in one (default: null)
-  if custom_zlib is used, custom_deflate is ignored since only the built in
-  zlib function will call custom_deflate*/
+  if custom_zlib is not null, custom_inflate is ignored (the zlib format uses deflate)*/
   unsigned (*custom_inflate)(unsigned char**, size_t*,
                              const unsigned char*, size_t,
                              const LodePNGDecompressSettings*);
@@ -281,13 +293,12 @@ Settings for zlib compression. Tweaking these settings tweaks the balance
 between speed and compression ratio.
 */
 typedef struct LodePNGCompressSettings LodePNGCompressSettings;
-struct LodePNGCompressSettings /*deflate = compress*/
-{
+struct LodePNGCompressSettings /*deflate = compress*/ {
   /*LZ77 related settings*/
   unsigned btype; /*the block type for LZ (0, 1, 2 or 3, see zlib standard). Should be 2 for proper compression.*/
   unsigned use_lz77; /*whether or not to use LZ77. Should be 1 for proper compression.*/
   unsigned windowsize; /*must be a power of two <= 32768. higher compresses more but is slower. Default value: 2048.*/
-  unsigned minmatch; /*mininum lz77 length. 3 is normally best, 6 can be better for some PNGs. Default: 0*/
+  unsigned minmatch; /*minimum lz77 length. 3 is normally best, 6 can be better for some PNGs. Default: 0*/
   unsigned nicematch; /*stop searching if >= this length found. Set to 258 for best compression. Default: 128*/
   unsigned lazymatching; /*use lazy matching: better compression but a bit slower. Default: true*/
 
@@ -315,8 +326,7 @@ Color mode of an image. Contains all information required to decode the pixel
 bits to RGBA colors. This information is the same as used in the PNG file
 format, and is used both for PNG and raw image data in LodePNG.
 */
-typedef struct LodePNGColorMode
-{
+typedef struct LodePNGColorMode {
   /*header (IHDR)*/
   LodePNGColorType colortype; /*color type, see PNG standard or documentation further in this header file*/
   unsigned bitdepth;  /*bits per sample, see PNG standard or documentation further in this header file*/
@@ -341,7 +351,7 @@ typedef struct LodePNGColorMode
   transparent color key (tRNS)
 
   This color uses the same bit depth as the bitdepth value in this struct, which can be 1-bit to 16-bit.
-  For greyscale PNGs, r, g and b will all 3 be set to the same.
+  For grayscale PNGs, r, g and b will all 3 be set to the same.
 
   When decoding, by default you can ignore this information, since LodePNG sets
   pixels with this key to transparent already in the raw RGBA output.
@@ -349,7 +359,7 @@ typedef struct LodePNGColorMode
   The color key is only supported for color types 0 and 2.
   */
   unsigned key_defined; /*is a transparent color key given? 0 = false, 1 = true*/
-  unsigned key_r;       /*red/greyscale component of color key*/
+  unsigned key_r;       /*red/grayscale component of color key*/
   unsigned key_g;       /*green component of color key*/
   unsigned key_b;       /*blue component of color key*/
 } LodePNGColorMode;
@@ -359,6 +369,8 @@ void lodepng_color_mode_init(LodePNGColorMode* info);
 void lodepng_color_mode_cleanup(LodePNGColorMode* info);
 /*return value is error code (0 means no error)*/
 unsigned lodepng_color_mode_copy(LodePNGColorMode* dest, const LodePNGColorMode* source);
+/* Makes a temporary LodePNGColorMode that does not need cleanup (no palette) */
+LodePNGColorMode lodepng_color_mode_make(LodePNGColorType colortype, unsigned bitdepth);
 
 void lodepng_palette_clear(LodePNGColorMode* info);
 /*add 1 color to the palette*/
@@ -370,7 +382,7 @@ unsigned lodepng_get_bpp(const LodePNGColorMode* info);
 /*get the amount of color channels used, based on colortype in the struct.
 If a palette is used, it counts as 1 channel.*/
 unsigned lodepng_get_channels(const LodePNGColorMode* info);
-/*is it a greyscale type? (only colortype 0 or 4)*/
+/*is it a grayscale type? (only colortype 0 or 4)*/
 unsigned lodepng_is_greyscale_type(const LodePNGColorMode* info);
 /*has it got an alpha channel? (only colortype 2 or 6)*/
 unsigned lodepng_is_alpha_type(const LodePNGColorMode* info);
@@ -392,8 +404,7 @@ size_t lodepng_get_raw_size(unsigned w, unsigned h, const LodePNGColorMode* colo
 
 #ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS
 /*The information of a Time chunk in PNG.*/
-typedef struct LodePNGTime
-{
+typedef struct LodePNGTime {
   unsigned year;    /*2 bytes used (0-65535)*/
   unsigned month;   /*1-12*/
   unsigned day;     /*1-31*/
@@ -404,28 +415,39 @@ typedef struct LodePNGTime
 #endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/
 
 /*Information about the PNG image, except pixels, width and height.*/
-typedef struct LodePNGInfo
-{
+typedef struct LodePNGInfo {
   /*header (IHDR), palette (PLTE) and transparency (tRNS) chunks*/
   unsigned compression_method;/*compression method of the original file. Always 0.*/
   unsigned filter_method;     /*filter method of the original file*/
-  unsigned interlace_method;  /*interlace method of the original file*/
+  unsigned interlace_method;  /*interlace method of the original file: 0=none, 1=Adam7*/
   LodePNGColorMode color;     /*color type and bits, palette and transparency of the PNG file*/
 
 #ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS
   /*
-  suggested background color chunk (bKGD)
-  This color uses the same color mode as the PNG (except alpha channel), which can be 1-bit to 16-bit.
+  Suggested background color chunk (bKGD)
+
+  This uses the same color mode and bit depth as the PNG (except no alpha channel),
+  with values truncated to the bit depth in the unsigned integer.
+
+  For grayscale and palette PNGs, the value is stored in background_r. The values
+  in background_g and background_b are then unused.
 
-  For greyscale PNGs, r, g and b will all 3 be set to the same. When encoding
-  the encoder writes the red one. For palette PNGs: When decoding, the RGB value
-  will be stored, not a palette index. But when encoding, specify the index of
-  the palette in background_r, the other two are then ignored.
+  So when decoding, you may get these in a different color mode than the one you requested
+  for the raw pixels.
 
-  The decoder does not use this background color to edit the color of pixels.
+  When encoding with auto_convert, you must use the color model defined in info_png.color for
+  these values. The encoder normally ignores info_png.color when auto_convert is on, but will
+  use it to interpret these values (and convert copies of them to its chosen color model).
+
+  When encoding, avoid setting this to an expensive color, such as a non-gray value
+  when the image is gray, or the compression will be worse since it will be forced to
+  write the PNG with a more expensive color mode (when auto_convert is on).
+
+  The decoder does not use this background color to edit the color of pixels. This is a
+  completely optional metadata feature.
   */
   unsigned background_defined; /*is a suggested background color given?*/
-  unsigned background_r;       /*red component of suggested background color*/
+  unsigned background_r;       /*red/gray/palette component of suggested background color*/
   unsigned background_g;       /*green component of suggested background color*/
   unsigned background_b;       /*blue component of suggested background color*/
 
@@ -436,6 +458,10 @@ typedef struct LodePNGInfo
   text_strings, while text_keys are keywords that give a short description what
   the actual text represents, e.g. Title, Author, Description, or anything else.
 
+  All the string fields below including keys, names and language tags are null terminated.
+  The PNG specification uses null characters for the keys, names and tags, and forbids null
+  characters to appear in the main text which is why we can use null termination everywhere here.
+
   A keyword is minimum 1 character and maximum 79 characters long. It's
   discouraged to use a single line length longer than 79 characters for texts.
 
@@ -468,11 +494,86 @@ typedef struct LodePNGInfo
   unsigned phys_unit; /*may be 0 (unknown unit) or 1 (metre)*/
 
   /*
-  unknown chunks
-  There are 3 buffers, one for each position in the PNG where unknown chunks can appear
-  each buffer contains all unknown chunks for that position consecutively
-  The 3 buffers are the unknown chunks between certain critical chunks:
-  0: IHDR-PLTE, 1: PLTE-IDAT, 2: IDAT-IEND
+  Color profile related chunks: gAMA, cHRM, sRGB, iCPP
+
+  LodePNG does not apply any color conversions on pixels in the encoder or decoder and does not interpret these color
+  profile values. It merely passes on the information. If you wish to use color profiles and convert colors, please
+  use these values with a color management library.
+
+  See the PNG, ICC and sRGB specifications for more information about the meaning of these values.
+  */
+
+  /* gAMA chunk: optional, overridden by sRGB or iCCP if those are present. */
+  unsigned gama_defined; /* Whether a gAMA chunk is present (0 = not present, 1 = present). */
+  unsigned gama_gamma;   /* Gamma exponent times 100000 */
+
+  /* cHRM chunk: optional, overridden by sRGB or iCCP if those are present. */
+  unsigned chrm_defined; /* Whether a cHRM chunk is present (0 = not present, 1 = present). */
+  unsigned chrm_white_x; /* White Point x times 100000 */
+  unsigned chrm_white_y; /* White Point y times 100000 */
+  unsigned chrm_red_x;   /* Red x times 100000 */
+  unsigned chrm_red_y;   /* Red y times 100000 */
+  unsigned chrm_green_x; /* Green x times 100000 */
+  unsigned chrm_green_y; /* Green y times 100000 */
+  unsigned chrm_blue_x;  /* Blue x times 100000 */
+  unsigned chrm_blue_y;  /* Blue y times 100000 */
+
+  /*
+  sRGB chunk: optional. May not appear at the same time as iCCP.
+  If gAMA is also present gAMA must contain value 45455.
+  If cHRM is also present cHRM must contain respectively 31270,32900,64000,33000,30000,60000,15000,6000.
+  */
+  unsigned srgb_defined; /* Whether an sRGB chunk is present (0 = not present, 1 = present). */
+  unsigned srgb_intent;  /* Rendering intent: 0=perceptual, 1=rel. colorimetric, 2=saturation, 3=abs. colorimetric */
+
+  /*
+  iCCP chunk: optional. May not appear at the same time as sRGB.
+
+  LodePNG does not parse or use the ICC profile (except its color space header field for an edge case), a
+  separate library to handle the ICC data (not included in LodePNG) format is needed to use it for color
+  management and conversions.
+
+  For encoding, if iCCP is present, gAMA and cHRM are recommended to be added as well with values that match the ICC
+  profile as closely as possible, if you wish to do this you should provide the correct values for gAMA and cHRM and
+  enable their '_defined' flags since LodePNG will not automatically compute them from the ICC profile.
+
+  For encoding, the ICC profile is required by the PNG specification to be an "RGB" profile for non-gray
+  PNG color types and a "GRAY" profile for gray PNG color types. If you disable auto_convert, you must ensure
+  the ICC profile type matches your requested color type, else the encoder gives an error. If auto_convert is
+  enabled (the default), and the ICC profile is not a good match for the pixel data, this will result in an encoder
+  error if the pixel data has non-gray pixels for a GRAY profile, or a silent less-optimal compression of the pixel
+  data if the pixels could be encoded as grayscale but the ICC profile is RGB.
+
+  To avoid this do not set an ICC profile in the image unless there is a good reason for it, and when doing so
+  make sure you compute it carefully to avoid the above problems.
+  */
+  unsigned iccp_defined;      /* Whether an iCCP chunk is present (0 = not present, 1 = present). */
+  char* iccp_name;            /* Null terminated string with profile name, 1-79 bytes */
+  /*
+  The ICC profile in iccp_profile_size bytes.
+  Don't allocate this buffer yourself. Use the init/cleanup functions
+  correctly and use lodepng_set_icc and lodepng_clear_icc.
+  */
+  unsigned char* iccp_profile;
+  unsigned iccp_profile_size; /* The size of iccp_profile in bytes */
+
+  /* End of color profile related chunks */
+
+
+  /*
+  unknown chunks: chunks not known by LodePNG, passed on byte for byte.
+
+  There are 3 buffers, one for each position in the PNG where unknown chunks can appear.
+  Each buffer contains all unknown chunks for that position consecutively.
+  The 3 positions are:
+  0: between IHDR and PLTE, 1: between PLTE and IDAT, 2: between IDAT and IEND.
+
+  For encoding, do not store critical chunks or known chunks that are enabled with a "_defined" flag
+  above in here, since the encoder will blindly follow this and could then encode an invalid PNG file
+  (such as one with two IHDR chunks or the disallowed combination of sRGB with iCCP). But do use
+  this if you wish to store an ancillary chunk that is not supported by LodePNG (such as sPLT or hIST),
+  or any non-standard PNG chunk.
+
   Do not allocate or traverse this data yourself. Use the chunk traversing functions declared
   later, such as lodepng_chunk_next and lodepng_chunk_append, to read/write this struct.
   */
@@ -488,12 +589,16 @@ void lodepng_info_cleanup(LodePNGInfo* info);
 unsigned lodepng_info_copy(LodePNGInfo* dest, const LodePNGInfo* source);
 
 #ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS
-void lodepng_clear_text(LodePNGInfo* info); /*use this to clear the texts again after you filled them in*/
 unsigned lodepng_add_text(LodePNGInfo* info, const char* key, const char* str); /*push back both texts at once*/
+void lodepng_clear_text(LodePNGInfo* info); /*use this to clear the texts again after you filled them in*/
 
-void lodepng_clear_itext(LodePNGInfo* info); /*use this to clear the itexts again after you filled them in*/
 unsigned lodepng_add_itext(LodePNGInfo* info, const char* key, const char* langtag,
                            const char* transkey, const char* str); /*push back the 4 texts of 1 chunk at once*/
+void lodepng_clear_itext(LodePNGInfo* info); /*use this to clear the itexts again after you filled them in*/
+
+/*replaces if exists*/
+unsigned lodepng_set_icc(LodePNGInfo* info, const char* name, const unsigned char* profile, unsigned profile_size);
+void lodepng_clear_icc(LodePNGInfo* info); /*use this to clear the texts again after you filled them in*/
 #endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/
 
 /*
@@ -516,11 +621,17 @@ unsigned lodepng_convert(unsigned char* out, const unsigned char* in,
 Settings for the decoder. This contains settings for the PNG and the Zlib
 decoder, but not the Info settings from the Info structs.
 */
-typedef struct LodePNGDecoderSettings
-{
+typedef struct LodePNGDecoderSettings {
   LodePNGDecompressSettings zlibsettings; /*in here is the setting to ignore Adler32 checksums*/
 
+  /* Check LodePNGDecompressSettings for more ignorable errors such as ignore_adler32 */
   unsigned ignore_crc; /*ignore CRC checksums*/
+  unsigned ignore_critical; /*ignore unknown critical chunks*/
+  unsigned ignore_end; /*ignore issues at end of file if possible (missing IEND chunk, too large chunk, ...)*/
+  /* TODO: make a system involving warnings with levels and a strict mode instead. Other potentially recoverable
+     errors: srgb rendering intent value, size of content of ancillary chunks, more than 79 characters for some
+     strings, placement/combination rules for ancillary chunks, crc of unknown chunks, allowed characters
+     in string keys, etc... */
 
   unsigned color_convert; /*whether to convert the PNG to the color type you want. Default: yes*/
 
@@ -536,10 +647,14 @@ void lodepng_decoder_settings_init(LodePNGDecoderSettings* settings);
 
 #ifdef LODEPNG_COMPILE_ENCODER
 /*automatically use color type with less bits per pixel if losslessly possible. Default: AUTO*/
-typedef enum LodePNGFilterStrategy
-{
+typedef enum LodePNGFilterStrategy {
   /*every filter at zero*/
-  LFS_ZERO,
+  LFS_ZERO = 0,
+  /*every filter at 1, 2, 3 or 4 (paeth), unlike LFS_ZERO not a good choice, but for testing*/
+  LFS_ONE = 1,
+  LFS_TWO = 2,
+  LFS_THREE = 3,
+  LFS_FOUR = 4,
   /*Use filter that gives minimum sum, as described in the official PNG filter heuristic.*/
   LFS_MINSUM,
   /*Use the filter type that gives smallest Shannon entropy for this scanline. Depending
@@ -554,36 +669,45 @@ typedef enum LodePNGFilterStrategy
   LFS_PREDEFINED
 } LodePNGFilterStrategy;
 
-/*Gives characteristics about the colors of the image, which helps decide which color model to use for encoding.
+/*Gives characteristics about the integer RGBA colors of the image (count, alpha channel usage, bit depth, ...),
+which helps decide which color model to use for encoding.
 Used internally by default if "auto_convert" is enabled. Public because it's useful for custom algorithms.*/
-typedef struct LodePNGColorProfile
-{
-  unsigned colored; /*not greyscale*/
-  unsigned key; /*if true, image is not opaque. Only if true and alpha is false, color key is possible.*/
-  unsigned short key_r; /*these values are always in 16-bit bitdepth in the profile*/
+typedef struct LodePNGColorStats {
+  unsigned colored; /*not grayscale*/
+  unsigned key; /*image is not opaque and color key is possible instead of full alpha*/
+  unsigned short key_r; /*key values, always as 16-bit, in 8-bit case the byte is duplicated, e.g. 65535 means 255*/
   unsigned short key_g;
   unsigned short key_b;
-  unsigned alpha; /*alpha channel or alpha palette required*/
-  unsigned numcolors; /*amount of colors, up to 257. Not valid if bits == 16.*/
-  unsigned char palette[1024]; /*Remembers up to the first 256 RGBA colors, in no particular order*/
-  unsigned bits; /*bits per channel (not for palette). 1,2 or 4 for greyscale only. 16 if 16-bit per channel required.*/
-} LodePNGColorProfile;
-
-void lodepng_color_profile_init(LodePNGColorProfile* profile);
-
-/*Get a LodePNGColorProfile of the image.*/
-unsigned lodepng_get_color_profile(LodePNGColorProfile* profile,
-                                   const unsigned char* image, unsigned w, unsigned h,
-                                   const LodePNGColorMode* mode_in);
-/*The function LodePNG uses internally to decide the PNG color with auto_convert.
-Chooses an optimal color model, e.g. grey if only grey pixels, palette if < 256 colors, ...*/
+  unsigned alpha; /*image is not opaque and alpha channel or alpha palette required*/
+  unsigned numcolors; /*amount of colors, up to 257. Not valid if bits == 16 or allow_palette is disabled.*/
+  unsigned char palette[1024]; /*Remembers up to the first 256 RGBA colors, in no particular order, only valid when numcolors is valid*/
+  unsigned bits; /*bits per channel (not for palette). 1,2 or 4 for grayscale only. 16 if 16-bit per channel required.*/
+  size_t numpixels;
+
+  /*user settings for computing/using the stats*/
+  unsigned allow_palette; /*default 1. if 0, disallow choosing palette colortype in auto_choose_color, and don't count numcolors*/
+  unsigned allow_greyscale; /*default 1. if 0, choose RGB or RGBA even if the image only has gray colors*/
+} LodePNGColorStats;
+
+void lodepng_color_stats_init(LodePNGColorStats* stats);
+
+/*Get a LodePNGColorStats of the image. The stats must already have been inited.*/
+void lodepng_compute_color_stats(LodePNGColorStats* stats,
+                                 const unsigned char* image, unsigned w, unsigned h,
+                                 const LodePNGColorMode* mode_in);
+/*Computes a minimal PNG color model that can contain all colors as indicated by the stats and it settings.
+The stats should be computed with lodepng_compute_color_stats.
+mode_in is raw color profile of the image the stats were computed on, to copy palette order from when relevant.
+Minimal PNG color model means the color type and bit depth that gives smallest amount of bits in the output image,
+e.g. gray if only grayscale pixels, palette if less than 256 colors, color key if only single transparent color, ...
+LodePNG uses this function internally if auto_convert is enabled (it is by default).
+*/
 unsigned lodepng_auto_choose_color(LodePNGColorMode* mode_out,
-                                   const unsigned char* image, unsigned w, unsigned h,
-                                   const LodePNGColorMode* mode_in);
+                                   const LodePNGColorMode* mode_in,
+                                   const LodePNGColorMode* stats);
 
 /*Settings for the encoder.*/
-typedef struct LodePNGEncoderSettings
-{
+typedef struct LodePNGEncoderSettings {
   LodePNGCompressSettings zlibsettings; /*settings for the zlib encoder, such as window size, ...*/
 
   unsigned auto_convert; /*automatically choose output PNG color type. Default: true*/
@@ -619,8 +743,7 @@ void lodepng_encoder_settings_init(LodePNGEncoderSettings* settings);
 
 #if defined(LODEPNG_COMPILE_DECODER) || defined(LODEPNG_COMPILE_ENCODER)
 /*The settings, state and information for extended encoding and decoding.*/
-typedef struct LodePNGState
-{
+typedef struct LodePNGState {
 #ifdef LODEPNG_COMPILE_DECODER
   LodePNGDecoderSettings decoder; /*the decoding settings*/
 #endif /*LODEPNG_COMPILE_DECODER*/
@@ -653,7 +776,7 @@ unsigned lodepng_decode(unsigned char** out, unsigned* w, unsigned* h,
 
 /*
 Read the PNG header, but not the actual data. This returns only the information
-that is in the header chunk of the PNG, such as width, height and color type. The
+that is in the IHDR chunk of the PNG, such as width, height and color type. The
 information is placed in the info_png field of the LodePNGState.
 */
 unsigned lodepng_inspect(unsigned* w, unsigned* h,
@@ -661,6 +784,20 @@ unsigned lodepng_inspect(unsigned* w, unsigned* h,
                          const unsigned char* in, size_t insize);
 #endif /*LODEPNG_COMPILE_DECODER*/
 
+/*
+Reads one metadata chunk (other than IHDR) of the PNG file and outputs what it
+read in the state. Returns error code on failure.
+Use lodepng_inspect first with a new state, then e.g. lodepng_chunk_find_const
+to find the desired chunk type, and if non null use lodepng_inspect_chunk (with
+chunk_pointer - start_of_file as pos).
+Supports most metadata chunks from the PNG standard (gAMA, bKGD, tEXt, ...).
+Ignores unsupported, unknown, non-metadata or IHDR chunks (without error).
+Requirements: &in[pos] must point to start of a chunk, must use regular
+lodepng_inspect first since format of most other chunks depends on IHDR, and if
+there is a PLTE chunk, that one must be inspected before tRNS or bKGD.
+*/
+unsigned lodepng_inspect_chunk(LodePNGState* state, size_t pos,
+                               const unsigned char* in, size_t insize);
 
 #ifdef LODEPNG_COMPILE_ENCODER
 /*This function allocates the out buffer with standard malloc and stores the size in *outsize.*/
@@ -674,11 +811,23 @@ The lodepng_chunk functions are normally not needed, except to traverse the
 unknown chunks stored in the LodePNGInfo struct, or add new ones to it.
 It also allows traversing the chunks of an encoded PNG file yourself.
 
-PNG standard chunk naming conventions:
-First byte: uppercase = critical, lowercase = ancillary
-Second byte: uppercase = public, lowercase = private
-Third byte: must be uppercase
-Fourth byte: uppercase = unsafe to copy, lowercase = safe to copy
+The chunk pointer always points to the beginning of the chunk itself, that is
+the first byte of the 4 length bytes.
+
+In the PNG file format, chunks have the following format:
+-4 bytes length: length of the data of the chunk in bytes (chunk itself is 12 bytes longer)
+-4 bytes chunk type (ASCII a-z,A-Z only, see below)
+-length bytes of data (may be 0 bytes if length was 0)
+-4 bytes of CRC, computed on chunk name + data
+
+The first chunk starts at the 8th byte of the PNG file, the entire rest of the file
+exists out of concatenated chunks with the above format.
+
+PNG standard chunk ASCII naming conventions:
+-First byte: uppercase = critical, lowercase = ancillary
+-Second byte: uppercase = public, lowercase = private
+-Third byte: must be uppercase
+-Fourth byte: uppercase = unsafe to copy, lowercase = safe to copy
 */
 
 /*
@@ -713,10 +862,24 @@ unsigned lodepng_chunk_check_crc(const unsigned char* chunk);
 /*generates the correct CRC from the data and puts it in the last 4 bytes of the chunk*/
 void lodepng_chunk_generate_crc(unsigned char* chunk);
 
-/*iterate to next chunks. don't use on IEND chunk, as there is no next chunk then*/
+/*
+Iterate to next chunks, allows iterating through all chunks of the PNG file.
+Input must be at the beginning of a chunk (result of a previous lodepng_chunk_next call,
+or the 8th byte of a PNG file which always has the first chunk), or alternatively may
+point to the first byte of the PNG file (which is not a chunk but the magic header, the
+function will then skip over it and return the first real chunk).
+Expects at least 8 readable bytes of memory in the input pointer.
+Will output pointer to the start of the next chunk or the end of the file if there
+is no more chunk after this. Start this process at the 8th byte of the PNG file.
+In a non-corrupt PNG file, the last chunk should have name "IEND".
+*/
 unsigned char* lodepng_chunk_next(unsigned char* chunk);
 const unsigned char* lodepng_chunk_next_const(const unsigned char* chunk);
 
+/*Finds the first chunk with the given type in the range [chunk, end), or returns NULL if not found.*/
+unsigned char* lodepng_chunk_find(unsigned char* chunk, const unsigned char* end, const char type[5]);
+const unsigned char* lodepng_chunk_find_const(const unsigned char* chunk, const unsigned char* end, const char type[5]);
+
 /*
 Appends chunk to the data in out. The given chunk should already have its chunk header.
 The out variable and outlength are updated to reflect the new reallocated buffer.
@@ -814,11 +977,9 @@ unsigned lodepng_save_file(const unsigned char* buffer, size_t buffersize, const
 
 #ifdef LODEPNG_COMPILE_CPP
 /* The LodePNG C++ wrapper uses std::vectors instead of manually allocated memory buffers. */
-namespace lodepng
-{
+namespace lodepng {
 #ifdef LODEPNG_COMPILE_PNG
-class State : public LodePNGState
-{
+class State : public LodePNGState {
   public:
     State();
     State(const State& other);
@@ -890,15 +1051,22 @@ TODO:
 [.] test if there are no memory leaks or security exploits - done a lot but needs to be checked often
 [.] check compatibility with various compilers  - done but needs to be redone for every newer version
 [X] converting color to 16-bit per channel types
-[ ] read all public PNG chunk types (but never let the color profile and gamma ones touch RGB values)
+[X] support color profile chunk types (but never let them touch RGB values by default)
+[ ] support all public PNG chunk types (almost done except sBIT, sPLT and hIST)
 [ ] make sure encoder generates no chunks with size > (2^31)-1
 [ ] partial decoding (stream processing)
 [X] let the "isFullyOpaque" function check color keys and transparent palettes too
 [X] better name for the variables "codes", "codesD", "codelengthcodes", "clcl" and "lldl"
-[ ] don't stop decoding on errors like 69, 57, 58 (make warnings)
+[ ] allow treating some errors like warnings, when image is recoverable (e.g. 69, 57, 58)
+[ ] make warnings like: oob palette, checksum fail, data after iend, wrong/unknown crit chunk, no null terminator in text, ...
+[ ] error messages with line numbers (and version)
+[ ] errors in state instead of as return code?
+[ ] new errors/warnings like suspiciously big decompressed ztxt or iccp chunk
 [ ] let the C++ wrapper catch exceptions coming from the standard library and return LodePNG error codes
 [ ] allow user to provide custom color conversion functions, e.g. for premultiplied alpha, padding bits or not, ...
 [ ] allow user to give data (void*) to custom allocator
+[ ] provide alternatives for C library functions not present on some platforms (memcpy, ...)
+[ ] rename "grey" to "gray" everywhere since "color" also uses US spelling (keep "grey" copies for backwards compatibility)
 */
 
 #endif /*LODEPNG_H inclusion guard*/
@@ -993,8 +1161,10 @@ The following features are supported by the decoder:
 *) zlib decompression (inflate)
 *) zlib compression (deflate)
 *) CRC32 and ADLER32 checksums
+*) colorimetric color profile conversions: currently experimentally available in lodepng_util.cpp only,
+   plus alternatively ability to pass on chroma/gamma/ICC profile information to other color management system.
 *) handling of unknown chunks, allowing making a PNG editor that stores custom and unknown chunks.
-*) the following chunks are supported (generated/interpreted) by both encoder and decoder:
+*) the following chunks are supported by both encoder and decoder:
     IHDR: header information
     PLTE: color palette
     IDAT: pixel data
@@ -1006,6 +1176,10 @@ The following features are supported by the decoder:
     bKGD: suggested background color
     pHYs: physical dimensions
     tIME: modification time
+    cHRM: RGB chromaticities
+    gAMA: RGB gamma correction
+    iCCP: ICC color profile
+    sRGB: rendering intent
 
 1.2. features not supported
 ---------------------------
@@ -1014,10 +1188,10 @@ The following features are _not_ supported:
 
 *) some features needed to make a conformant PNG-Editor might be still missing.
 *) partial loading/stream processing. All data must be available and is processed in one call.
-*) The following public chunks are not supported but treated as unknown chunks by LodePNG
-    cHRM, gAMA, iCCP, sRGB, sBIT, hIST, sPLT
-   Some of these are not supported on purpose: LodePNG wants to provide the RGB values
-   stored in the pixels, not values modified by system dependent gamma or color models.
+*) The following public chunks are not (yet) supported but treated as unknown chunks by LodePNG:
+    sBIT
+    hIST
+    sPLT
 
 
 2. C and C++ version
@@ -1091,7 +1265,7 @@ LodePNGColorMode info_raw
 When decoding, here you can specify which color type you want
 the resulting raw image to be. If this is different from the colortype of the
 PNG, then the decoder will automatically convert the result. This conversion
-always works, except if you want it to convert a color PNG to greyscale or to
+always works, except if you want it to convert a color PNG to grayscale or to
 a palette with missing colors.
 
 By default, 32-bit color is used for the result.
@@ -1187,7 +1361,7 @@ can encode the colors of all pixels without information loss.
 An important thing to note about LodePNG, is that the color type of the PNG, and
 the color type of the raw image, are completely independent. By default, when
 you decode a PNG, you get the result as a raw image in the color type you want,
-no matter whether the PNG was encoded with a palette, greyscale or RGBA color.
+no matter whether the PNG was encoded with a palette, grayscale or RGBA color.
 And if you encode an image, by default LodePNG will automatically choose the PNG
 color type that gives good compression based on the values of colors and amount
 of colors in the image. It can be configured to let you control it instead as
@@ -1195,10 +1369,10 @@ well, though.
 
 To be able to do this, LodePNG does conversions from one color mode to another.
 It can convert from almost any color type to any other color type, except the
-following conversions: RGB to greyscale is not supported, and converting to a
+following conversions: RGB to grayscale is not supported, and converting to a
 palette when the palette doesn't have a required color is not supported. This is
 not supported on purpose: this is information loss which requires a color
-reduction algorithm that is beyong the scope of a PNG encoder (yes, RGB to grey
+reduction algorithm that is beyond the scope of a PNG encoder (yes, RGB to gray
 is easy, but there are multiple ways if you want to give some channels more
 weight).
 
@@ -1219,10 +1393,10 @@ decoding to have another color type, a conversion is done by LodePNG.
 
 The PNG specification gives the following color types:
 
-0: greyscale, bit depths 1, 2, 4, 8, 16
+0: grayscale, bit depths 1, 2, 4, 8, 16
 2: RGB, bit depths 8 and 16
 3: palette, bit depths 1, 2, 4 and 8
-4: greyscale with alpha, bit depths 8 and 16
+4: grayscale with alpha, bit depths 8 and 16
 6: RGBA, bit depths 8 and 16
 
 Bit depth is the amount of bits per pixel per color channel. So the total amount
@@ -1271,15 +1445,22 @@ To avoid some confusion:
  the raw image correctly before encoding.
 -both encoder and decoder use the same color converter.
 
+The function lodepng_convert does the color conversion. It is available in the
+interface but normally isn't needed since the encoder and decoder already call
+it.
+
 Non supported color conversions:
--color to greyscale: no error is thrown, but the result will look ugly because
-only the red channel is taken
--anything to palette when that palette does not have that color in it: in this
-case an error is thrown
+-color to grayscale when non-gray pixels are present: no error is thrown, but
+the result will look ugly because only the red channel is taken (it assumes all
+three channels are the same in this case so ignores green and blue). The reason
+no error is given is to allow converting from three-channel grayscale images to
+one-channel even if there are numerical imprecisions.
+-anything to palette when the palette does not have an exact match for a from-color
+in it: in this case an error is thrown
 
 Supported color conversions:
 -anything to 8-bit RGB, 8-bit RGBA, 16-bit RGB, 16-bit RGBA
--any grey or grey+alpha, to grey or grey+alpha
+-any gray or gray+alpha, to gray or gray+alpha
 -anything to a palette, as long as the palette has the requested colors in it
 -removing alpha channel
 -higher to smaller bitdepth, and vice versa
@@ -1292,10 +1473,6 @@ false.
 as the PNG has, by setting the color_convert setting to false. Settings in
 info_raw are then ignored.
 
-The function lodepng_convert does the color conversion. It is available in the
-interface but normally isn't needed since the encoder and decoder already call
-it.
-
 6.3. padding bits
 -----------------
 
@@ -1304,7 +1481,7 @@ have a bit amount that isn't a multiple of 8, then padding bits are used so that
 scanline starts at a fresh byte. But that is NOT true for the LodePNG raw input and output.
 The raw input image you give to the encoder, and the raw output image you get from the decoder
 will NOT have these padding bits, e.g. in the case of a 1-bit image with a width
-of 7 pixels, the first pixel of the second scanline will the the 8th bit of the first byte,
+of 7 pixels, the first pixel of the second scanline will the 8th bit of the first byte,
 not the first bit of a new byte.
 
 6.4. A note about 16-bits per channel and endianness
@@ -1421,7 +1598,7 @@ The LodePNGInfo struct contains fields with the unknown chunk in it. It has 3
 buffers (each with size) to contain 3 types of unknown chunks:
 the ones that come before the PLTE chunk, the ones that come between the PLTE
 and the IDAT chunks, and the ones that come after the IDAT chunks.
-It's necessary to make the distionction between these 3 cases because the PNG
+It's necessary to make the distinction between these 3 cases because the PNG
 standard forces to keep the ordering of unknown chunks compared to the critical
 chunks, but does not force any other ordering rules.
 
@@ -1504,7 +1681,7 @@ C and C++.
 *) Other Compilers
 
 If you encounter problems on any compilers, feel free to let me know and I may
-try to fix it if the compiler is modern and standards complient.
+try to fix it if the compiler is modern and standards compliant.
 
 
 10. examples
@@ -1519,8 +1696,7 @@ examples can be found on the LodePNG website.
 #include "lodepng.h"
 #include <iostream>
 
-int main(int argc, char *argv[])
-{
+int main(int argc, char *argv[]) {
   const char* filename = argc > 1 ? argv[1] : "test.png";
 
   //load and decode
@@ -1539,8 +1715,7 @@ int main(int argc, char *argv[])
 
 #include "lodepng.h"
 
-int main(int argc, char *argv[])
-{
+int main(int argc, char *argv[]) {
   unsigned error;
   unsigned char* image;
   size_t width, height;
@@ -1566,6 +1741,8 @@ For decoding:
 state.decoder.zlibsettings.ignore_adler32: ignore ADLER32 checksums
 state.decoder.zlibsettings.custom_...: use custom inflate function
 state.decoder.ignore_crc: ignore CRC checksums
+state.decoder.ignore_critical: ignore unknown critical chunks
+state.decoder.ignore_end: ignore missing IEND chunk. May fail if this corruption causes other errors
 state.decoder.color_convert: convert internal PNG color to chosen one
 state.decoder.read_text_chunks: whether to read in text metadata chunks
 state.decoder.remember_unknown_chunks: whether to read in unknown chunks
@@ -1607,11 +1784,29 @@ yyyymmdd.
 Some changes aren't backwards compatible. Those are indicated with a (!)
 symbol.
 
+Not all changes are listed here, the commit history in github lists more:
+https://github.com/lvandeve/lodepng
+
+*) 14 aug 2019: around 25% faster decoding thanks to huffman lookup tables.
+*) 15 jun 2019 (!): auto_choose_color API changed (for bugfix: don't use palette
+   if gray ICC profile) and non-ICC LodePNGColorProfile renamed to LodePNGColorStats.
+*) 30 dec 2018: code style changes only: removed newlines before opening braces.
+*) 10 sep 2018: added way to inspect metadata chunks without full decoding.
+*) 19 aug 2018 (!): fixed color mode bKGD is encoded with and made it use
+   palette index in case of palette.
+*) 10 aug 2018 (!): added support for gAMA, cHRM, sRGB and iCCP chunks. This
+   change is backwards compatible unless you relied on unknown_chunks for those.
+*) 11 jun 2018: less restrictive check for pixel size integer overflow
+*) 14 jan 2018: allow optionally ignoring a few more recoverable errors
+*) 17 sep 2017: fix memory leak for some encoder input error cases
+*) 27 nov 2016: grey+alpha auto color model detection bugfix
+*) 18 apr 2016: Changed qsort to custom stable sort (for platforms w/o qsort).
 *) 09 apr 2016: Fixed colorkey usage detection, and better file loading (within
    the limits of pure C90).
 *) 08 dec 2015: Made load_file function return error if file can't be opened.
 *) 24 okt 2015: Bugfix with decoding to palette output.
 *) 18 apr 2015: Boundary PM instead of just package-merge for faster encoding.
+*) 24 aug 2014: Moved to github
 *) 23 aug 2014: Reduced needless memory usage of decoder.
 *) 28 jun 2014: Removed fix_png setting, always support palette OOB for
     simplicity. Made ColorProfile public.
@@ -1754,5 +1949,5 @@ Domain: gmail dot com.
 Account: lode dot vandevenne.
 
 
-Copyright (c) 2005-2016 Lode Vandevenne
+Copyright (c) 2005-2019 Lode Vandevenne
 */
diff --git a/src/zopflipng/lodepng/lodepng_util.cpp b/src/zopflipng/lodepng/lodepng_util.cpp
index 76efdea..9ceebe7 100644
--- a/src/zopflipng/lodepng/lodepng_util.cpp
+++ b/src/zopflipng/lodepng/lodepng_util.cpp
@@ -1,7 +1,7 @@
 /*
 LodePNG Utils
 
-Copyright (c) 2005-2014 Lode Vandevenne
+Copyright (c) 2005-2019 Lode Vandevenne
 
 This software is provided 'as-is', without any express or implied
 warranty. In no event will the authors be held liable for any damages
@@ -24,13 +24,12 @@ freely, subject to the following restrictions:
 */
 
 #include "lodepng_util.h"
-#include <iostream>
+#include <iostream>  // TODO: remove, don't print stuff from here, return errors instead
+#include <stdlib.h> /* allocations */
 
-namespace lodepng
-{
+namespace lodepng {
 
-LodePNGInfo getPNGHeaderInfo(const std::vector<unsigned char>& png)
-{
+LodePNGInfo getPNGHeaderInfo(const std::vector<unsigned char>& png) {
   unsigned w, h;
   lodepng::State state;
   lodepng_inspect(&w, &h, &state, &png[0], png.size());
@@ -38,23 +37,21 @@ LodePNGInfo getPNGHeaderInfo(const std::vector<unsigned char>& png)
 }
 
 unsigned getChunkInfo(std::vector<std::string>& names, std::vector<size_t>& sizes,
-                      const std::vector<unsigned char>& png)
-{
+                      const std::vector<unsigned char>& png) {
   // Listing chunks is based on the original file, not the decoded png info.
   const unsigned char *chunk, *begin, *end, *next;
   end = &png.back() + 1;
   begin = chunk = &png.front() + 8;
 
-  while(chunk + 8 < end && chunk >= begin)
-  {
+  while(chunk + 8 < end && chunk >= begin) {
     char type[5];
     lodepng_chunk_type(type, chunk);
     if(std::string(type).size() != 4) return 1;
 
     unsigned length = lodepng_chunk_length(chunk);
-    if(chunk + length + 12 > end) return 1;
     names.push_back(type);
     sizes.push_back(length);
+    if(chunk + length + 12 > end) return 1;
 
     next = lodepng_chunk_next_const(chunk);
     if (next <= chunk) return 1; // integer overflow
@@ -65,16 +62,14 @@ unsigned getChunkInfo(std::vector<std::string>& names, std::vector<size_t>& size
 
 unsigned getChunks(std::vector<std::string> names[3],
                    std::vector<std::vector<unsigned char> > chunks[3],
-                   const std::vector<unsigned char>& png)
-{
+                   const std::vector<unsigned char>& png) {
   const unsigned char *chunk, *next, *begin, *end;
   end = &png.back() + 1;
   begin = chunk = &png.front() + 8;
 
   int location = 0;
 
-  while(chunk + 8 < end && chunk >= begin)
-  {
+  while(chunk + 8 < end && chunk >= begin) {
     char type[5];
     lodepng_chunk_type(type, chunk);
     std::string name(type);
@@ -83,24 +78,15 @@ unsigned getChunks(std::vector<std::string> names[3],
     next = lodepng_chunk_next_const(chunk);
     if (next <= chunk) return 1; // integer overflow
 
-    if(name == "IHDR")
-    {
+    if(name == "IHDR") {
       location = 0;
-    }
-    else if(name == "PLTE")
-    {
+    } else if(name == "PLTE") {
       location = 1;
-    }
-    else if(name == "IDAT")
-    {
+    } else if(name == "IDAT") {
       location = 2;
-    }
-    else if(name == "IEND")
-    {
+    } else if(name == "IEND") {
       break; // anything after IEND is not part of the PNG or the 3 groups here.
-    }
-    else
-    {
+    } else {
       if(next > end) return 1; // invalid chunk, content too far
       names[location].push_back(name);
       chunks[location].push_back(std::vector<unsigned char>(chunk, next));
@@ -113,8 +99,7 @@ unsigned getChunks(std::vector<std::string> names[3],
 
 
 unsigned insertChunks(std::vector<unsigned char>& png,
-                      const std::vector<std::vector<unsigned char> > chunks[3])
-{
+                      const std::vector<std::vector<unsigned char> > chunks[3]) {
   const unsigned char *chunk, *next, *begin, *end;
   end = &png.back() + 1;
   begin = chunk = &png.front() + 8;
@@ -123,8 +108,7 @@ unsigned insertChunks(std::vector<unsigned char>& png,
   long l1 = 0; //location 1: PLTE-l1-IDAT (or IHDR-l0-l1-IDAT)
   long l2 = 0; //location 2: IDAT-l2-IEND
 
-  while(chunk + 8 < end && chunk >= begin)
-  {
+  while(chunk + 8 < end && chunk >= begin) {
     char type[5];
     lodepng_chunk_type(type, chunk);
     std::string name(type);
@@ -133,17 +117,12 @@ unsigned insertChunks(std::vector<unsigned char>& png,
     next = lodepng_chunk_next_const(chunk);
     if (next <= chunk) return 1; // integer overflow
 
-    if(name == "PLTE")
-    {
+    if(name == "PLTE") {
       if(l0 == 0) l0 = chunk - begin + 8;
-    }
-    else if(name == "IDAT")
-    {
+    } else if(name == "IDAT") {
       if(l0 == 0) l0 = chunk - begin + 8;
       if(l1 == 0) l1 = chunk - begin + 8;
-    }
-    else if(name == "IEND")
-    {
+    } else if(name == "IEND") {
       if(l2 == 0) l2 = chunk - begin + 8;
     }
 
@@ -164,8 +143,7 @@ unsigned insertChunks(std::vector<unsigned char>& png,
 }
 
 unsigned getFilterTypesInterlaced(std::vector<std::vector<unsigned char> >& filterTypes,
-                                  const std::vector<unsigned char>& png)
-{
+                                  const std::vector<unsigned char>& png) {
   //Get color type and interlace type
   lodepng::State state;
   unsigned w, h;
@@ -181,14 +159,12 @@ unsigned getFilterTypesInterlaced(std::vector<std::vector<unsigned char> >& filt
 
   std::vector<unsigned char> zdata;
 
-  while(chunk + 8 < end && chunk >= begin)
-  {
+  while(chunk + 8 < end && chunk >= begin) {
     char type[5];
     lodepng_chunk_type(type, chunk);
-    if(std::string(type).size() != 4) return 1; //Probably not a PNG file
+    if(std::string(type).size() != 4) break; //Probably not a PNG file
 
-    if(std::string(type) == "IDAT")
-    {
+    if(std::string(type) == "IDAT") {
       const unsigned char* cdata = lodepng_chunk_data_const(chunk);
       unsigned clength = lodepng_chunk_length(chunk);
       if(chunk + clength + 12 > end || clength > png.size() || chunk + clength + 12 < begin) {
@@ -196,37 +172,32 @@ unsigned getFilterTypesInterlaced(std::vector<std::vector<unsigned char> >& filt
         return 1;
       }
 
-      for(unsigned i = 0; i < clength; i++)
-      {
+      for(unsigned i = 0; i < clength; i++) {
         zdata.push_back(cdata[i]);
       }
     }
 
     next = lodepng_chunk_next_const(chunk);
-    if (next <= chunk) return 1; // integer overflow
+    if (next <= chunk) break; // integer overflow
     chunk = next;
   }
 
-  //Decompress all IDAT data
+  //Decompress all IDAT data (if the while loop ended early, this might fail)
   std::vector<unsigned char> data;
   error = lodepng::decompress(data, &zdata[0], zdata.size());
 
   if(error) return 1;
 
-  if(state.info_png.interlace_method == 0)
-  {
+  if(state.info_png.interlace_method == 0) {
     filterTypes.resize(1);
 
     //A line is 1 filter byte + all pixels
     size_t linebytes = 1 + lodepng_get_raw_size(w, 1, &state.info_png.color);
 
-    for(size_t i = 0; i < data.size(); i += linebytes)
-    {
+    for(size_t i = 0; i < data.size(); i += linebytes) {
       filterTypes[0].push_back(data[i]);
     }
-  }
-  else
-  {
+  } else {
     //Interlaced
     filterTypes.resize(7);
     static const unsigned ADAM7_IX[7] = { 0, 4, 0, 2, 0, 1, 0 }; /*x start values*/
@@ -234,15 +205,13 @@ unsigned getFilterTypesInterlaced(std::vector<std::vector<unsigned char> >& filt
     static const unsigned ADAM7_DX[7] = { 8, 8, 4, 4, 2, 2, 1 }; /*x delta values*/
     static const unsigned ADAM7_DY[7] = { 8, 8, 8, 4, 4, 2, 2 }; /*y delta values*/
     size_t pos = 0;
-    for(size_t j = 0; j < 7; j++)
-    {
+    for(size_t j = 0; j < 7; j++) {
       unsigned w2 = (w - ADAM7_IX[j] + ADAM7_DX[j] - 1) / ADAM7_DX[j];
       unsigned h2 = (h - ADAM7_IY[j] + ADAM7_DY[j] - 1) / ADAM7_DY[j];
       if(ADAM7_IX[j] >= w) w2 = 0;
       if(ADAM7_IY[j] >= h) h2 = 0;
       size_t linebytes = 1 + lodepng_get_raw_size(w2, 1, &state.info_png.color);
-      for(size_t i = 0; i < h2; i++)
-      {
+      for(size_t i = 0; i < h2; i++) {
         filterTypes[j].push_back(data[pos]);
         pos += linebytes;
       }
@@ -252,18 +221,14 @@ unsigned getFilterTypesInterlaced(std::vector<std::vector<unsigned char> >& filt
 }
 
 
-unsigned getFilterTypes(std::vector<unsigned char>& filterTypes, const std::vector<unsigned char>& png)
-{
+unsigned getFilterTypes(std::vector<unsigned char>& filterTypes, const std::vector<unsigned char>& png) {
   std::vector<std::vector<unsigned char> > passes;
   unsigned error = getFilterTypesInterlaced(passes, png);
   if(error) return error;
 
-  if(passes.size() == 1)
-  {
+  if(passes.size() == 1) {
     filterTypes.swap(passes[0]);
-  }
-  else
-  {
+  } else {
     lodepng::State state;
     unsigned w, h;
     lodepng_inspect(&w, &h, &state, &png[0], png.size());
@@ -273,16 +238,14 @@ unsigned getFilterTypes(std::vector<unsigned char>& filterTypes, const std::vect
     filter corresponding the closest to what it would be for non-interlaced
     image.
     */
-    for(size_t i = 0; i < h; i++)
-    {
+    for(size_t i = 0; i < h; i++) {
       filterTypes.push_back(i % 2 == 0 ? passes[5][i / 2] : passes[6][i / 2]);
     }
   }
   return 0; /* OK */
 }
 
-int getPaletteValue(const unsigned char* data, size_t i, int bits)
-{
+int getPaletteValue(const unsigned char* data, size_t i, int bits) {
   if(bits == 8) return data[i];
   else if(bits == 4) return (data[i / 2] >> ((i % 2) * 4)) & 15;
   else if(bits == 2) return (data[i / 4] >> ((i % 4) * 2)) & 3;
@@ -290,68 +253,1229 @@ int getPaletteValue(const unsigned char* data, size_t i, int bits)
   else return 0;
 }
 
+
+////////////////////////////////////////////////////////////////////////////////
+
+#ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS
+
+
+
+// Only temporarily here until this is integrated into lodepng.c(pp)
+#define LODEPNG_MAX(a, b) (((a) > (b)) ? (a) : (b))
+#define LODEPNG_MIN(a, b) (((a) < (b)) ? (a) : (b))
+
+// Only temporarily here until this is integrated into lodepng.c(pp)
+#ifdef LODEPNG_COMPILE_ALLOCATORS
+static void* lodepng_malloc(size_t size) {
+  return malloc(size);
+}
+static void lodepng_free(void* ptr) {
+  free(ptr);
+}
+#else /*LODEPNG_COMPILE_ALLOCATORS*/
+void* lodepng_malloc(size_t size);
+void lodepng_free(void* ptr);
+#endif /*LODEPNG_COMPILE_ALLOCATORS*/
+
+/* avoid needing <float.h> for FLT_MAX */
+static const float lodepng_flt_max = 3.40282346638528859811704183484516925e38f;
+
+/* powf polyfill, 5-6 digits accurate, 33% slower than powf, assumes IEEE
+32-bit float, but other than that multiplatform and no math lib needed
+(note: powf also isn't in ISO C90, and pow is slower). */
+static float lodepng_powf(float x, float y) {
+  float j, t0, t1;
+  int i = 0;
+  /* handle all the special floating point rules */
+  if(x == 1 || y == 0) return 1;
+  if(!(x > 0 && x <= lodepng_flt_max && y == y && y <= lodepng_flt_max && y >= -lodepng_flt_max)) {
+    if(y == 1) return x; /* preserves negative-0 */
+    if(x != x || y != y) return x + y; /* nan */
+    if(x > 0) {
+      if(x > lodepng_flt_max) return y <= 0 ? (y == 0 ? 1 : 0) : x; /* x = +infinity */
+    } else {
+      if(!(y < -1073741824.0f || y > 1073741824.0f)) { /* large y always even integer, but cast would overflow */
+        i = (int)y;
+        if(i != y) return (x < -lodepng_flt_max) ? (y < 0 ? 0 : (1 / 0.0f)) : (x == 0 ? (y < 0 ? 1 / 0.0f : 0) : (0 / 0.0f));
+        if(i & 1) return x == 0 ? (y < 0 ? (1 / x) : x) : -lodepng_powf(-x, y);
+      }
+      if(x == 0) return y <= 0 ? (1 / 0.0f) : 0;
+      if(x < -lodepng_flt_max) return y <= 0 ? (y == 0 ? 1 : 0) : ((i & 1) ? (-1 / 0.0f) : (1 / 0.0f)); /* x = -infinity */
+      x = -x;
+      if(x == 1) return 1;
+    }
+    if(y < -lodepng_flt_max || y > lodepng_flt_max) return ((x < 1) != (y > 0)) ? (y < 0 ? -y : y) : 0;
+  }
+
+  j = 0;
+  while(x < (1.0f / 65536)) { j -= 16; x *= 65536.0f; }
+  while(x > 65536) { j += 16; x *= (1.0f / 65536); }
+  while(x < 1) { j--; x *= 2.0f; }
+  while(x > 2) { j++; x *= 0.5f; }
+  /* polynomial to approximate log2(x) with x in range 1..2 */
+  t0 = -0.393118410458557f + x * (-0.0883639468229365f + x * (0.466142650227994f + x * 0.0153397331014276f));
+  t1 = 0.0907447971403586f + x * (0.388892024755479f + x * 0.137228280305862f);
+  x = t0 / t1 + j;
+
+  x *= y; /* using the formula exp2(y * log2(x)) */
+
+  if(!(x > -128.0f && x < 128.0f)) return x > 0 ? (1 / 0.0f) : 0; /* prevent int overflow */
+  i = (int)x;
+  x -= i;
+  /* polynomial to approximate exp2(x) with x in range -1..1 */
+  t0 = 1.0f + x * (0.41777833582744256f + x * (0.0728482595347711f + x * 0.005635023478609625f));
+  t1 = 1.0f + x * (-0.27537016151408167f + x * 0.023501446055084033f);
+  while(i <= -31) { t0 *= (1.0f / 2147483648.0f); i += 31; }
+  while(i >= 31) { t0 *= 2147483648.0f; i -= 31; }
+  return (i < 0) ? (t0 / (t1 * (1 << -i))) : ((t0 * (1 << i)) / t1);
+}
+
+/* Parameters of a tone reproduction curve, either with a power law formula or with a lookup table. */
+typedef struct {
+  unsigned type; /* 0=linear, 1=lut, 2 = simple gamma, 3-6 = parametric (matches ICC parametric types 1-4) */
+  float* lut; /* for type 1 */
+  size_t lut_size;
+  float gamma; /* for type 2 and more */
+  float a, b, c, d, e, f; /* parameters for type 3-7 */
+} LodePNGICCCurve;
+
+void lodepng_icc_curve_init(LodePNGICCCurve* curve) {
+  curve->lut = 0;
+  curve->lut_size = 0;
+}
+
+void lodepng_icc_curve_cleanup(LodePNGICCCurve* curve) {
+  lodepng_free(curve->lut);
+}
+
+/* Values parsed from ICC profile, see parseICC for more information about this subset.*/
+typedef struct {
+  /* 0 = color model not supported by PNG (CMYK, Lab, ...), 1 = gray, 2 = RGB */
+  int inputspace;
+  int version_major;
+  int version_minor;
+  int version_bugfix;
+
+  /* The whitepoint of the profile connection space (PCS). Should always be D50, but parsed and used anyway.
+  (to be clear, whitepoint and illuminant are synonyms in practice, but here field "illuminant" is ICC's
+  "global" whitepoint that is always D50, and the field "white" below allows deriving the whitepoint of
+  the particular RGB space represented here) */
+  float illuminant[3];
+
+  /* if true, has chromatic adaptation matrix that must be used. If false, you must compute a chromatic adaptation
+  matrix yourself from "illuminant" and "white". */
+  unsigned has_chad;
+  float chad[9]; /* chromatic adaptation matrix, if given */
+
+  /* The whitepoint of the RGB color space as stored in the ICC file. If has_chad, must be adapted with the
+  chad matrix to become the one we need to go to absolute XYZ (in fact ICC implies it should then be
+  exactly D50 in the file, redundantly, before this transformation with chad), else use as-is (then its
+  values can actually be something else than D50, and are the ones we need). */
+  unsigned has_whitepoint;
+  float white[3];
+  /* Chromaticities of the RGB space in XYZ color space, but given such that you must still
+  whitepoint adapt them from D50 to the RGB space whitepoint to go to absolute XYZ (if has_chad,
+  with chad, else with bradford adaptation matrix from illuminant to white). */
+  unsigned has_chromaticity;
+  float red[3];
+  float green[3];
+  float blue[3];
+
+  unsigned has_trc; /* TRC = tone reproduction curve (aka "gamma correction") */
+
+  /* TRC's for the three channels (only first one used if grayscale) */
+  LodePNGICCCurve trc[3];
+} LodePNGICC;
+
+void lodepng_icc_init(LodePNGICC* icc) {
+  lodepng_icc_curve_init(&icc->trc[0]);
+  lodepng_icc_curve_init(&icc->trc[1]);
+  lodepng_icc_curve_init(&icc->trc[2]);
+}
+
+void lodepng_icc_cleanup(LodePNGICC* icc) {
+  lodepng_icc_curve_cleanup(&icc->trc[0]);
+  lodepng_icc_curve_cleanup(&icc->trc[1]);
+  lodepng_icc_curve_cleanup(&icc->trc[2]);
+}
+
+/* ICC tone response curve, nonlinear (encoded) to linear.
+Input and output in range 0-1. If color was integer 0-255, multiply with (1.0f/255)
+to get the correct floating point behavior.
+Outside of range 0-1, will not clip but either return x itself, or in cases
+where it makes sense, a value defined by the same function.
+NOTE: ICC requires clipping, but we do that only later when converting float to integer.*/
+static float iccForwardTRC(const LodePNGICCCurve* curve, float x) {
+  if(curve->type == 0) {
+    return x;
+  }
+  if(curve->type == 1) { /* Lookup table */
+    float v0, v1, fraction;
+    size_t index;
+    if(!curve->lut) return 0; /* error */
+    if(x < 0) return x;
+    index = (size_t)(x * (curve->lut_size - 1));
+    if(index >= curve->lut_size) return x;
+
+    /* LERP */
+    v0 = curve->lut[index];
+    v1 = (index + 1 < curve->lut_size) ? curve->lut[index + 1] : 1.0f;
+    fraction = (x * (curve->lut_size - 1)) - index;
+    return v0 * (1 - fraction) + v1 * fraction;
+  }
+  if(curve->type == 2) {
+    /* Gamma expansion */
+    return (x > 0) ? lodepng_powf(x, curve->gamma) : x;
+  }
+  /* TODO: all the ones below are untested */
+  if(curve->type == 3) {
+    if(x < 0) return x;
+    return x >= (-curve->b / curve->a) ? (lodepng_powf(curve->a * x + curve->b, curve->gamma) + curve->c) : 0;
+  }
+  if(curve->type == 4) {
+    if(x < 0) return x;
+    return x >= (-curve->b / curve->a) ? (lodepng_powf(curve->a * x + curve->b, curve->gamma) + curve->c) : curve->c;
+  }
+  if(curve->type == 5) {
+    return x >= curve->d ? (lodepng_powf(curve->a * x + curve->b, curve->gamma)) : (curve->c * x);
+  }
+  if(curve->type == 6) {
+    return x >= curve->d ? (lodepng_powf(curve->a * x + curve->b, curve->gamma) + curve->c) : (curve->c * x + curve->f);
+  }
+  return 0;
+}
+
+/* ICC tone response curve, linear to nonlinear (encoded).
+Input and output in range 0-1. Outside of that range, will not clip but either
+return x itself, or in cases where it makes sense, a value defined by the same function.
+NOTE: ICC requires clipping, but we do that only later when converting float to integer.*/
+static float iccBackwardTRC(const LodePNGICCCurve* curve, float x) {
+  if(curve->type == 0) {
+    return x;
+  }
+  if(curve->type == 1) {
+    size_t a, b, m;
+    float v;
+    if(x <= 0) return x;
+    if(x >= 1) return x;
+    /* binary search in the table */
+    /* TODO: use faster way of inverting the lookup table */
+    a = 0;
+    b = curve->lut_size;
+    for(;;) {
+      if(a == b) return curve->lut[a];
+      if(a + 1 == b) {
+        /* LERP */
+        float v0 = curve->lut[a];
+        float v1 = curve->lut[b];
+        float fraction;
+        if(v0 == v1) return v0;
+        fraction = (x - v0) / (v1 - v0);
+        return v0 * (1 - fraction) + v1 * fraction;
+      }
+      m = (a + b) / 2u;
+      v = curve->lut[m];
+      if(v > x) {
+        b = m;
+      } else {
+        a = m;
+      }
+    }
+    return 0;
+  }
+  if(curve->type == 2) {
+    /* Gamma compression */
+    return (x > 0) ? lodepng_powf(x, 1.0f / curve->gamma) : x;
+  }
+  /* TODO: all the ones below are untested  */
+  if(curve->type == 3) {
+    if(x < 0) return x;
+    return x > 0 ? ((lodepng_powf(x, 1.0f / curve->gamma) - curve->b) / curve->a) : (-curve->b / curve->a);
+  }
+  if(curve->type == 4) {
+    if(x < 0) return x;
+    return x > curve->c ?
+        ((lodepng_powf(x - curve->c, 1.0f / curve->gamma) - curve->b) / curve->a) :
+        (-curve->b / curve->a);
+  }
+  if(curve->type == 5) {
+    return x > (curve->c * curve->d) ?
+        ((lodepng_powf(x, 1.0f / curve->gamma) - curve->b) / curve->a) :
+        (x / curve->c);
+  }
+  if(curve->type == 6) {
+    return x > (curve->c * curve->d + curve->f) ?
+        ((lodepng_powf(x - curve->c, 1.0f / curve->gamma) - curve->b) / curve->a) :
+        ((x - curve->f) / curve->c);
+  }
+  return 0;
+}
+
+static unsigned decodeICCUint16(const unsigned char* data, size_t size, size_t* pos) {
+  *pos += 2;
+  if (*pos > size) return 0;
+  return (unsigned)((data[*pos - 2] << 8) | (data[*pos - 1]));
+}
+
+static unsigned decodeICCUint32(const unsigned char* data, size_t size, size_t* pos) {
+  *pos += 4;
+  if (*pos > size) return 0;
+  return (unsigned)((data[*pos - 4] << 24) | (data[*pos - 3] << 16) | (data[*pos - 2] << 8) | (data[*pos - 1] << 0));
+}
+
+static int decodeICCInt32(const unsigned char* data, size_t size, size_t* pos) {
+  *pos += 4;
+  if (*pos > size) return 0;
+  /*TODO: this is incorrect if sizeof(int) != 4*/
+  return (data[*pos - 4] << 24) | (data[*pos - 3] << 16) | (data[*pos - 2] << 8) | (data[*pos - 1] << 0);
+}
+
+static float decodeICC15Fixed16(const unsigned char* data, size_t size, size_t* pos) {
+  return decodeICCInt32(data, size, pos) / 65536.0;
+}
+
+static unsigned isICCword(const unsigned char* data, size_t size, size_t pos, const char* word) {
+  if(pos + 4 > size) return 0;
+  return data[pos + 0] == (unsigned char)word[0] &&
+         data[pos + 1] == (unsigned char)word[1] &&
+         data[pos + 2] == (unsigned char)word[2] &&
+         data[pos + 3] == (unsigned char)word[3];
+}
+
+/* Parses a subset of the ICC profile, supporting the necessary mix of ICC v2
+and ICC v4 required to correctly convert the RGB color space to XYZ.
+Does not parse values not related to this specific PNG-related purpose, and
+does not support non-RGB profiles or lookup-table based chroma (but it
+supports lookup tables for TRC aka "gamma"). */
+static unsigned parseICC(LodePNGICC* icc, const unsigned char* data, size_t size) {
+  size_t i, j;
+  size_t pos = 0;
+  unsigned version;
+  unsigned inputspace;
+  size_t numtags;
+
+  if(size < 132) return 1; /* Too small to be a valid icc profile. */
+
+  icc->has_chromaticity = 0;
+  icc->has_whitepoint = 0;
+  icc->has_trc = 0;
+  icc->has_chad = 0;
+
+  icc->trc[0].type = icc->trc[1].type = icc->trc[2].type = 0;
+  icc->white[0] = icc->white[1] = icc->white[2] = 0;
+  icc->red[0] = icc->red[1] = icc->red[2] = 0;
+  icc->green[0] = icc->green[1] = icc->green[2] = 0;
+  icc->blue[0] = icc->blue[1] = icc->blue[2] = 0;
+
+  pos = 8;
+  version = decodeICCUint32(data, size, &pos);
+  if(pos >= size) return 1;
+  icc->version_major = (int)((version >> 24) & 255);
+  icc->version_minor = (int)((version >> 20) & 15);
+  icc->version_bugfix = (int)((version >> 16) & 15);
+
+  pos = 16;
+  inputspace = decodeICCUint32(data, size, &pos);
+  if(pos >= size) return 1;
+  if(inputspace == 0x47524159) {
+    /* The string  "GRAY" as unsigned 32-bit int. */
+    icc->inputspace = 1;
+  } else if(inputspace == 0x52474220) {
+    /* The string  "RGB " as unsigned 32-bit int. */
+    icc->inputspace = 2;
+  } else {
+    /* unsupported by PNG (CMYK, YCbCr, Lab, HSV, ...) */
+    icc->inputspace = 0;
+  }
+
+  /* Should always be 0.9642, 1.0, 0.8249 */
+  pos = 68;
+  icc->illuminant[0] = decodeICC15Fixed16(data, size, &pos);
+  icc->illuminant[1] = decodeICC15Fixed16(data, size, &pos);
+  icc->illuminant[2] = decodeICC15Fixed16(data, size, &pos);
+
+  pos = 128;
+  numtags = decodeICCUint32(data, size, &pos);
+  if(pos >= size) return 1;
+  /* scan for tags we want to handle */
+  for(i = 0; i < numtags; i++) {
+    size_t offset;
+    unsigned tagsize;
+    size_t namepos = pos;
+    pos += 4;
+    offset = decodeICCUint32(data, size, &pos);
+    tagsize = decodeICCUint32(data, size, &pos);
+    if(pos >= size || offset >= size) return 1;
+    if(offset + tagsize > size) return 1;
+    if(tagsize < 8) return 1;
+
+    if(isICCword(data, size, namepos, "wtpt")) {
+      offset += 8; /* skip tag and reserved */
+      icc->white[0] = decodeICC15Fixed16(data, size, &offset);
+      icc->white[1] = decodeICC15Fixed16(data, size, &offset);
+      icc->white[2] = decodeICC15Fixed16(data, size, &offset);
+      icc->has_whitepoint = 1;
+    } else if(isICCword(data, size, namepos, "rXYZ")) {
+      offset += 8; /* skip tag and reserved */
+      icc->red[0] = decodeICC15Fixed16(data, size, &offset);
+      icc->red[1] = decodeICC15Fixed16(data, size, &offset);
+      icc->red[2] = decodeICC15Fixed16(data, size, &offset);
+      icc->has_chromaticity = 1;
+    } else if(isICCword(data, size, namepos, "gXYZ")) {
+      offset += 8; /* skip tag and reserved */
+      icc->green[0] = decodeICC15Fixed16(data, size, &offset);
+      icc->green[1] = decodeICC15Fixed16(data, size, &offset);
+      icc->green[2] = decodeICC15Fixed16(data, size, &offset);
+      icc->has_chromaticity = 1;
+    } else if(isICCword(data, size, namepos, "bXYZ")) {
+      offset += 8; /* skip tag and reserved */
+      icc->blue[0] = decodeICC15Fixed16(data, size, &offset);
+      icc->blue[1] = decodeICC15Fixed16(data, size, &offset);
+      icc->blue[2] = decodeICC15Fixed16(data, size, &offset);
+      icc->has_chromaticity = 1;
+    } else if(isICCword(data, size, namepos, "chad")) {
+      offset += 8; /* skip datatype keyword "sf32" and reserved */
+      for(j = 0; j < 9; j++) {
+        icc->chad[j] = decodeICC15Fixed16(data, size, &offset);
+      }
+      icc->has_chad = 1;
+    } else if(isICCword(data, size, namepos, "rTRC") ||
+              isICCword(data, size, namepos, "gTRC") ||
+              isICCword(data, size, namepos, "bTRC") ||
+              isICCword(data, size, namepos, "kTRC")) {
+      char c = (char)data[namepos];
+      /* both 'k' and 'r' are stored in channel 0 */
+      int channel = (c == 'b') ? 2 : (c == 'g' ? 1 : 0);
+      /* "curv": linear, gamma power or LUT */
+      if(isICCword(data, size, offset, "curv")) {
+        size_t count;
+        LodePNGICCCurve* trc = &icc->trc[channel];
+        icc->has_trc = 1;
+        offset += 8; /* skip tag "curv" and reserved */
+        count = decodeICCUint32(data, size, &offset);
+        if(count == 0) {
+          trc->type = 0; /* linear */
+        } else if(count == 1) {
+          trc->type = 2; /* gamma */
+          trc->gamma = decodeICCUint16(data, size, &offset) / 256.0f;
+        } else {
+          trc->type = 1; /* LUT */
+          if(offset + count * 2 > size || count > 16777216) return 1; /* also avoid crazy count */
+          trc->lut_size = count;
+          trc->lut = (float*)lodepng_malloc(count * sizeof(float));
+          for(j = 0; j < count; j++) {
+            trc->lut[j] = decodeICCUint16(data, size, &offset) * (1.0f / 65535.0f);
+          }
+        }
+      }
+      /* "para": parametric formula with gamma power, multipliers, biases and comparison point */
+      /* TODO: test this on a realistic sample */
+      if(isICCword(data, size, offset, "para")) {
+        unsigned type;
+        LodePNGICCCurve* trc = &icc->trc[channel];
+        icc->has_trc = 1;
+        offset += 8; /* skip tag "para" and reserved */
+        type = decodeICCUint16(data, size, &offset);
+        offset += 2;
+        if(type > 4) return 1; /* unknown parametric curve type */
+        trc->type = type + 2;
+        trc->gamma = decodeICC15Fixed16(data, size, &offset);
+        if(type >= 1) {
+          trc->a = decodeICC15Fixed16(data, size, &offset);
+          trc->b = decodeICC15Fixed16(data, size, &offset);
+        }
+        if(type >= 2) {
+          trc->c = decodeICC15Fixed16(data, size, &offset);
+        }
+        if(type >= 3) {
+          trc->d = decodeICC15Fixed16(data, size, &offset);
+        }
+        if(type == 4) {
+          trc->e = decodeICC15Fixed16(data, size, &offset);
+          trc->f = decodeICC15Fixed16(data, size, &offset);
+        }
+      }
+      /* TODO: verify: does the "chrm" tag participate in computation so should be parsed? */
+    }
+    /* Return error if any parse went beyond the filesize. Note that the
+    parsing itself was always safe since it bound-checks inside. */
+    if(offset > size) return 1;
+  }
+
+  return 0;
+}
+
+/* Multiplies 3 vector values with 3x3 matrix */
+static void mulMatrix(float* x2, float* y2, float* z2, const float* m, double x, double y, double z) {
+  /* double used as inputs even though in general the images are float, so the sums happen in
+  double precision, because float can give numerical problems for nearby values */
+  *x2 = x * m[0] + y * m[1] + z * m[2];
+  *y2 = x * m[3] + y * m[4] + z * m[5];
+  *z2 = x * m[6] + y * m[7] + z * m[8];
+}
+
+static void mulMatrixMatrix(float* result, const float* a, const float* b) {
+  int i;
+  float temp[9]; /* temp is to allow result and a or b to be the same */
+  mulMatrix(&temp[0], &temp[3], &temp[6], a, b[0], b[3], b[6]);
+  mulMatrix(&temp[1], &temp[4], &temp[7], a, b[1], b[4], b[7]);
+  mulMatrix(&temp[2], &temp[5], &temp[8], a, b[2], b[5], b[8]);
+  for(i = 0; i < 9; i++) result[i] = temp[i];
+}
+
+/* Inverts 3x3 matrix in place */
+static unsigned invMatrix(float* m) {
+  int i;
+  /* double used instead of float for intermediate computations to avoid
+  intermediate numerical precision issues */
+  double e0 = (double)m[4] * m[8] - (double)m[5] * m[7];
+  double e3 = (double)m[5] * m[6] - (double)m[3] * m[8];
+  double e6 = (double)m[3] * m[7] - (double)m[4] * m[6];
+  /* inverse determinant */
+  double d = 1.0 / (m[0] * e0 + m[1] * e3 + m[2] * e6);
+  float result[9];
+  if((d > 0 ? d : -d) > 1e15) return 1; /* error, likely not invertible */
+  result[0] = e0 * d;
+  result[1] = ((double)m[2] * m[7] - (double)m[1] * m[8]) * d;
+  result[2] = ((double)m[1] * m[5] - (double)m[2] * m[4]) * d;
+  result[3] = e3 * d;
+  result[4] = ((double)m[0] * m[8] - (double)m[2] * m[6]) * d;
+  result[5] = ((double)m[3] * m[2] - (double)m[0] * m[5]) * d;
+  result[6] = e6 * d;
+  result[7] = ((double)m[6] * m[1] - (double)m[0] * m[7]) * d;
+  result[8] = ((double)m[0] * m[4] - (double)m[3] * m[1]) * d;
+  for(i = 0; i < 9; i++) m[i] = result[i];
+  return 0; /* ok */
+}
+
+/* Get the matrix to go from linear RGB to XYZ given the RGB whitepoint and chromaticities in XYZ colorspace */
+static unsigned getChrmMatrixXYZ(float* m,
+                                 float wX, float wY, float wZ,
+                                 float rX, float rY, float rZ,
+                                 float gX, float gY, float gZ,
+                                 float bX, float bY, float bZ) {
+  float t[9];
+  float rs, gs, bs;
+  t[0] = rX; t[1] = gX; t[2] = bX;
+  t[3] = rY; t[4] = gY; t[5] = bY;
+  t[6] = rZ; t[7] = gZ; t[8] = bZ;
+  if(invMatrix(t)) return 1; /* error, not invertible */
+  mulMatrix(&rs, &gs, &bs, t, wX, wY, wZ);
+  m[0] = rs * rX; m[1] = gs * gX; m[2] = bs * bX;
+  m[3] = rs * rY; m[4] = gs * gY; m[5] = bs * bY;
+  m[6] = rs * rZ; m[7] = gs * gZ; m[8] = bs * bZ;
+  return 0;
+}
+
+/* Get the matrix to go from linear RGB to XYZ given the RGB whitepoint and chromaticities in xy colorspace */
+static unsigned getChrmMatrixXY(float* m,
+                                float wx, float wy,
+                                float rx, float ry,
+                                float gx, float gy,
+                                float bx, float by) {
+  if(wy == 0 || ry == 0 || gy == 0 || by == 0) {
+    return 1; /* error, division through zero */
+  } else {
+    float wX = wx / wy, wY = 1, wZ = (1 - wx - wy) / wy;
+    float rX = rx / ry, rY = 1, rZ = (1 - rx - ry) / ry;
+    float gX = gx / gy, gY = 1, gZ = (1 - gx - gy) / gy;
+    float bX = bx / by, bY = 1, bZ = (1 - bx - by) / by;
+    return getChrmMatrixXYZ(m, wX, wY, wZ, rX, rY, rZ, gX, gY, gZ, bX, bY, bZ);
+  }
+}
+
+/* Returns matrix that adapts from source whitepoint 0 to destination whitepoint 1.
+Types: 0=XYZ scaling, 1=Bradford, 2=Vonkries */
+static unsigned getAdaptationMatrix(float* m, int type,
+                                    float wx0, float wy0, float wz0,
+                                    float wx1, float wy1, float wz1) {
+  int i;
+  static const float bradford[9] = {
+    0.8951, 0.2664, -0.1614,
+    -0.7502, 1.7135, 0.0367,
+    0.0389, -0.0685, 1.0296
+  };
+  static const float bradfordinv[9] = {
+    0.9869929, -0.1470543, 0.1599627,
+    0.4323053, 0.5183603, 0.0492912,
+   -0.0085287, 0.0400428, 0.9684867
+  };
+  static const float vonkries[9] = {
+    0.40024, 0.70760, -0.08081,
+    -0.22630, 1.16532, 0.04570,
+    0.00000, 0.00000, 0.91822,
+  };
+  static const float vonkriesinv[9] = {
+    1.8599364, -1.1293816, 0.2198974,
+    0.3611914, 0.6388125, -0.0000064,
+   0.0000000, 0.0000000, 1.0890636
+  };
+  if(type == 0) {
+    for(i = 0; i < 9; i++) m[i] = 0;
+    m[0] = wx1 / wx0;
+    m[4] = wy1 / wy0;
+    m[8] = wz1 / wz0;
+  } else {
+    const float* cat = (type == 1) ? bradford : vonkries;
+    const float* inv = (type == 1) ? bradfordinv : vonkriesinv;
+    float rho0, gam0, bet0, rho1, gam1, bet1, rho2, gam2, bet2;
+    mulMatrix(&rho0, &gam0, &bet0, cat, wx0, wy0, wz0);
+    mulMatrix(&rho1, &gam1, &bet1, cat, wx1, wy1, wz1);
+    rho2 = rho1 / rho0;
+    gam2 = gam1 / gam0;
+    bet2 = bet1 / bet0;
+    /* Multiply diagonal matrix with cat */
+    for(i = 0; i < 3; i++) {
+      m[i + 0] = rho2 * cat[i + 0];
+      m[i + 3] = gam2 * cat[i + 3];
+      m[i + 6] = bet2 * cat[i + 6];
+    }
+    mulMatrixMatrix(m, inv, m);
+  }
+  return 0; /* ok */
+}
+
+/* validate whether the ICC profile is supported here for PNG */
+static unsigned validateICC(const LodePNGICC* icc) {
+  /* disable for unsupported things in the icc profile */
+  if(icc->inputspace == 0) return 0;
+  /* if we didn't recognize both chrm and trc, then maybe the ICC uses data
+  types not supported here yet, so fall back to not using it. */
+  if(icc->inputspace == 2) {
+    /* RGB profile should have chromaticities */
+    if(!icc->has_chromaticity) return 0;
+  }
+  /* An ICC profile without whitepoint is invalid for the kind of profiles used here. */
+  if(!icc->has_whitepoint) return 0;
+  if(!icc->has_trc) return 0;
+  return 1; /* ok */
+}
+
+/* Returns chromaticity matrix for given ICC profile, adapted from ICC's
+global illuminant as necessary.
+Also returns the profile's whitepoint.
+In case of a gray profile (icc->inputspace == 1), the identity matrix will be returned
+so in that case you could skip the transform. */
+static unsigned getICCChrm(float m[9], float whitepoint[3], const LodePNGICC* icc) {
+  size_t i;
+  if(icc->inputspace == 2) { /* RGB profile */
+    float red[3], green[3], blue[3];
+    float white[3]; /* the whitepoint of the RGB color space (absolute) */
+    /* Adaptation matrix a.
+    This is an adaptation needed for ICC's file format (due to it using
+    an internal global illuminant unrelated to the actual images) */
+    float a[9] = {1,0,0, 0,1,0, 0,0,1};
+    /* If the profile has chromatic adaptation matrix "chad", use that one,
+    else compute it from the illuminant and whitepoint. */
+    if(icc->has_chad) {
+      for(i = 0; i < 9; i++) a[i] = icc->chad[i];
+      invMatrix(a);
+    } else {
+      if(getAdaptationMatrix(a, 1, icc->illuminant[0], icc->illuminant[1], icc->illuminant[2],
+                             icc->white[0], icc->white[1], icc->white[2])) {
+        return 1; /* error computing matrix */
+      }
+    }
+    /* If the profile has a chad, then also the RGB's whitepoint must also be adapted from it (and the one
+    given is normally D50). If it did not have a chad, then the whitepoint given is already the adapted one. */
+    if(icc->has_chad) {
+      mulMatrix(&white[0], &white[1], &white[2], a, icc->white[0], icc->white[1], icc->white[2]);
+    } else {
+      for(i = 0; i < 3; i++) white[i] = icc->white[i];
+    }
+
+    mulMatrix(&red[0], &red[1], &red[2], a, icc->red[0], icc->red[1], icc->red[2]);
+    mulMatrix(&green[0], &green[1], &green[2], a, icc->green[0], icc->green[1], icc->green[2]);
+    mulMatrix(&blue[0], &blue[1], &blue[2], a, icc->blue[0], icc->blue[1], icc->blue[2]);
+
+    if(getChrmMatrixXYZ(m, white[0], white[1], white[2], red[0], red[1], red[2],
+                        green[0], green[1], green[2], blue[0], blue[1], blue[2])) {
+      return 1; /* error computing matrix */
+    }
+    /* output absolute whitepoint of the original RGB model */
+    whitepoint[0] = white[0];
+    whitepoint[1] = white[1];
+    whitepoint[2] = white[2];
+  } else {
+    /* output the unity matrix, for doing no transform */
+    m[0] = m[4] = m[8] = 1;
+    m[1] = m[2] = m[3] = m[5] = m[6] = m[7] = 0;
+    /* grayscale, don't do anything. That means we are implicitely using equal energy whitepoint "E", indicate
+    this to the output. */
+    whitepoint[0] = whitepoint[1] = whitepoint[2] = 1;
+  }
+  return 0; /* success */
+}
+
+/* Outputs whitepoint and matrix to go from the icc or info profile (depending on what was in the PNG) to XYZ,
+without applying any (rendering intent related) whitepoint adaptation */
+static unsigned getChrm(float m[9], float whitepoint[3], unsigned use_icc,
+                        const LodePNGICC* icc, const LodePNGInfo* info) {
+  size_t i;
+  if(use_icc) {
+    if(getICCChrm(m, whitepoint, icc)) return 1;  /* error in the matrix computations */
+  } else if(info->chrm_defined && !info->srgb_defined) {
+    float wx = info->chrm_white_x / 100000.0f, wy = info->chrm_white_y / 100000.0f;
+    float rx = info->chrm_red_x / 100000.0f, ry = info->chrm_red_y / 100000.0f;
+    float gx = info->chrm_green_x / 100000.0f, gy = info->chrm_green_y / 100000.0f;
+    float bx = info->chrm_blue_x / 100000.0f, by = info->chrm_blue_y / 100000.0f;
+    if(getChrmMatrixXY(m, wx, wy, rx, ry, gx, gy, bx, by)) return 1; /* returns if error */
+    /* Output whitepoint, xyY to XYZ: */
+    whitepoint[0] = wx / wy;
+    whitepoint[1] = 1;
+    whitepoint[2] = (1 - wx - wy) / wy;
+  } else {
+    /* the standard linear sRGB to XYZ matrix */
+    static const float srgb[9] = {
+        0.4124564f, 0.3575761f, 0.1804375f,
+        0.2126729f, 0.7151522f, 0.0721750f,
+        0.0193339f, 0.1191920f, 0.9503041f
+    };
+    for(i = 0; i < 9; i++) m[i] = srgb[i];
+    /* sRGB's whitepoint xyY "0.3127,0.3290,1" in XYZ: */
+    whitepoint[0] = 0.9504559270516716f;
+    whitepoint[1] = 1;
+    whitepoint[2] = 1.0890577507598784f;
+  }
+  return 0;
+}
+
+/* Returns whether the color chunks in info represent the default PNG sRGB,
+which is when either no colorometry fields are present at all, or an srgb
+field or chrm/gama field with default values are present.
+ICC chunks representing sRGB are currently considered not the same. */
+static unsigned isSRGB(const LodePNGInfo* info) {
+  if(!info) return 1; /* the default is considered sRGB. */
+
+  /* TODO: support some ICC profiles that represent sRGB too. Tricky due to
+  possible slight deviations and many ways of representing its gamma function. */
+  if(info->iccp_defined) return 0;
+
+  if(info->srgb_defined) return 1;
+
+  /* The gamma chunk is unable to represent sRGB's two-part gamma, so cannot
+  be sRGB, even if it's the default 45455. */
+  if(info->gama_defined) return 0;
+
+  if(info->chrm_defined) {
+    if(info->chrm_white_x != 31270 || info->chrm_white_y != 32900) return 0;
+    if(info->chrm_red_x != 64000 || info->chrm_red_y != 33000) return 0;
+    if(info->chrm_green_x != 30000 || info->chrm_green_y != 60000) return 0;
+    if(info->chrm_blue_x != 15000 || info->chrm_blue_y != 6000) return 0;
+  }
+
+  return 1;
+}
+
+/* Checks whether the RGB models are equal (chromaticities, ...). The raw byte
+format is allowed to be different. Input pointers are allowed to be null,
+they then represent the default PNG sRGB (same as having no color model
+chunks at all or an srgb chunk in the PNG) */
+static unsigned modelsEqual(const LodePNGState* state_a,
+                            const LodePNGState* state_b) {
+  size_t i;
+  const LodePNGInfo* a = state_a ? &state_a->info_png : 0;
+  const LodePNGInfo* b = state_b ? &state_b->info_png : 0;
+  if(isSRGB(a) != isSRGB(b)) return 0;
+  /* now a and b are guaranteed to be non-NULL */
+  if(a->iccp_defined != b->iccp_defined) return 0;
+  if(a->iccp_defined) {
+    if(a->iccp_profile_size != b->iccp_profile_size) return 0;
+    /* TODO: return equal in more cases, such as when two ICC profiles that are
+    not byte-for-byte equal, but represent the same color model. */
+    for(i = 0; i < a->iccp_profile_size; i++) {
+      if(a->iccp_profile[i] != b->iccp_profile[i]) return 0;
+    }
+    /* since the ICC model overrides gamma and chrm, those can be ignored. */
+    /* TODO: this doesn't cover the case where the ICC profile is invalid */
+    return 1;
+  }
+
+  if(a->srgb_defined != b->srgb_defined) return 0;
+  if(a->srgb_defined) {
+    /* since the sRGB model overrides gamma and chrm, those can be ignored.
+    srgb_intent not checked since the conversion ignores it */
+    return 1;
+  }
+
+  if(a->gama_defined != b->gama_defined) return 0;
+  if(a->gama_defined) {
+    if(a->gama_gamma != b->gama_gamma) return 0;
+  }
+
+  if(a->chrm_defined != b->chrm_defined) return 0;
+  if(a->chrm_defined) {
+    if(a->chrm_white_x != b->chrm_white_x) return 0;
+    if(a->chrm_white_y != b->chrm_white_y) return 0;
+    if(a->chrm_red_x != b->chrm_red_x) return 0;
+    if(a->chrm_red_y != b->chrm_red_y) return 0;
+    if(a->chrm_green_x != b->chrm_green_x) return 0;
+    if(a->chrm_green_y != b->chrm_green_y) return 0;
+    if(a->chrm_blue_x != b->chrm_blue_x) return 0;
+    if(a->chrm_blue_y != b->chrm_blue_y) return 0;
+  }
+
+  return 1;
+}
+
+/* Converts in-place. Does not clamp. Do not use for integer input, make table instead there. */
+static void convertToXYZ_gamma(float* out, const float* in, unsigned w, unsigned h,
+                               const LodePNGInfo* info, unsigned use_icc, const LodePNGICC* icc) {
+  size_t i, c;
+  size_t n = w * h;
+  for(i = 0; i < n * 4; i++) {
+    out[i] = in[i];
+  }
+  if(use_icc) {
+    for(i = 0; i < n; i++) {
+      for(c = 0; c < 3; c++) {
+        /* TODO: this is likely very slow */
+        out[i * 4 + c] = iccForwardTRC(&icc->trc[c], in[i * 4 + c]);
+      }
+    }
+  } else if(info->gama_defined && !info->srgb_defined) {
+    /* nothing to do if gamma is 1 */
+    if(info->gama_gamma != 100000) {
+      float gamma = 100000.0f / info->gama_gamma;
+      for(i = 0; i < n; i++) {
+        for(c = 0; c < 3; c++) {
+          float v = in[i * 4 + c];
+          out[i * 4 + c] = (v <= 0) ? v : lodepng_powf(v, gamma);
+        }
+      }
+    }
+  } else {
+    for(i = 0; i < n; i++) {
+      for(c = 0; c < 3; c++) {
+        /* sRGB gamma expand */
+        float v = in[i * 4 + c];
+        out[i * 4 + c] = (v < 0.04045f) ? (v / 12.92f) : lodepng_powf((v + 0.055f) / 1.055f, 2.4f);
+      }
+    }
+  }
+}
+
+/* Same as convertToXYZ_gamma, but creates a lookup table rather than operating on an image */
+static void convertToXYZ_gamma_table(float* out, size_t n, size_t c,
+                                     const LodePNGInfo* info, unsigned use_icc, const LodePNGICC* icc) {
+  size_t i;
+  float mul = 1.0f / (n - 1);
+  if(use_icc) {
+    for(i = 0; i < n; i++) {
+      float v = i * mul;
+      out[i] = iccForwardTRC(&icc->trc[c], v);
+    }
+  } else if(info->gama_defined && !info->srgb_defined) {
+    /* no power needed if gamma is 1 */
+    if(info->gama_gamma == 100000) {
+      for(i = 0; i < n; i++) {
+        out[i] = i * mul;
+      }
+    } else {
+      float gamma = 100000.0f / info->gama_gamma;
+      for(i = 0; i < n; i++) {
+        float v = i * mul;
+        out[i] = lodepng_powf(v, gamma);
+      }
+    }
+  } else {
+    for(i = 0; i < n; i++) {
+      /* sRGB gamma expand */
+      float v = i * mul;
+      out[i] = (v < 0.04045f) ? (v / 12.92f) : lodepng_powf((v + 0.055f) / 1.055f, 2.4f);
+    }
+  }
+}
+
+/* In-place */
+static unsigned convertToXYZ_chrm(float* im, unsigned w, unsigned h,
+                                  const LodePNGInfo* info, unsigned use_icc, const LodePNGICC* icc,
+                                  float whitepoint[3]) {
+  unsigned error = 0;
+  size_t i;
+  size_t n = w * h;
+  float m[9]; /* XYZ to linear RGB matrix */
+
+  /* Must be called even for grayscale, to get the correct whitepoint to output */
+  error = getChrm(m, whitepoint, use_icc, icc, info);
+  if(error) return error;
+
+  /* Note: no whitepoint adaptation done to m here, because we only do the
+  adaptation in convertFromXYZ (we only whitepoint adapt when going to the
+  target RGB space, but here we're going from the source RGB space to XYZ) */
+
+  /* Apply the above computed linear-RGB-to-XYZ matrix to the pixels.
+  Skip the transform if it's the unit matrix (which is the case if grayscale profile) */
+  if(!use_icc || icc->inputspace == 2) {
+    for(i = 0; i < n; i++) {
+      size_t j = i * 4;
+      mulMatrix(&im[j + 0], &im[j + 1], &im[j + 2], m, im[j + 0], im[j + 1], im[j + 2]);
+    }
+  }
+
+  return 0;
+}
+
+unsigned convertToXYZ(float* out, float whitepoint[3], const unsigned char* in,
+                      unsigned w, unsigned h, const LodePNGState* state) {
+  unsigned error = 0;
+  size_t i;
+  size_t n = w * h;
+  const LodePNGColorMode* mode_in = &state->info_raw;
+  const LodePNGInfo* info = &state->info_png;
+  unsigned char* data = 0;
+  float* gammatable = 0;
+  int bit16 = mode_in->bitdepth > 8;
+  size_t num = bit16 ? 65536 : 256;
+  LodePNGColorMode tempmode = lodepng_color_mode_make(LCT_RGBA, bit16 ? 16 : 8);
+
+
+  unsigned use_icc = 0;
+  LodePNGICC icc;
+  lodepng_icc_init(&icc);
+  if(info->iccp_defined) {
+    error = parseICC(&icc, info->iccp_profile, info->iccp_profile_size);
+    if(error) goto cleanup; /* corrupted ICC profile */
+    use_icc = validateICC(&icc);
+  }
+
+  data = (unsigned char*)lodepng_malloc(w * h * (bit16 ? 8 : 4));
+  error = lodepng_convert(data, in, &tempmode, mode_in, w, h);
+  if(error) goto cleanup;
+
+  /* Handle transfer function */
+  {
+    float* gammatable_r;
+    float* gammatable_g;
+    float* gammatable_b;
+
+    /* RGB ICC, can have three different transfer functions */
+    if(use_icc && icc.inputspace == 2) {
+      gammatable = (float*)lodepng_malloc(num * 3 * sizeof(float));
+      gammatable_r = &gammatable[num * 0];
+      gammatable_g = &gammatable[num * 1];
+      gammatable_b = &gammatable[num * 2];
+      convertToXYZ_gamma_table(gammatable_r, num, 0, info, use_icc, &icc);
+      convertToXYZ_gamma_table(gammatable_g, num, 1, info, use_icc, &icc);
+      convertToXYZ_gamma_table(gammatable_b, num, 2, info, use_icc, &icc);
+    } else {
+      gammatable = (float*)lodepng_malloc(num * sizeof(float));
+      gammatable_r = gammatable_g = gammatable_b = gammatable;
+      convertToXYZ_gamma_table(gammatable, num, 0, info, use_icc, &icc);
+    }
+
+    if(bit16) {
+      for(i = 0; i < n; i++) {
+        out[i * 4 + 0] = gammatable_r[data[i * 8 + 0] * 256u + data[i * 8 + 1]];
+        out[i * 4 + 1] = gammatable_g[data[i * 8 + 2] * 256u + data[i * 8 + 3]];
+        out[i * 4 + 2] = gammatable_b[data[i * 8 + 4] * 256u + data[i * 8 + 5]];
+        out[i * 4 + 3] = (data[i * 8 + 6] * 256 + data[i * 8 + 7]) * (1 / 65535.0f);
+      }
+    } else {
+      for(i = 0; i < n; i++) {
+        out[i * 4 + 0] = gammatable_r[data[i * 4 + 0]];
+        out[i * 4 + 1] = gammatable_g[data[i * 4 + 1]];
+        out[i * 4 + 2] = gammatable_b[data[i * 4 + 2]];
+        out[i * 4 + 3] = data[i * 4 + 3] * (1 / 255.0f);
+      }
+    }
+  }
+
+  convertToXYZ_chrm(out, w, h, info, use_icc, &icc, whitepoint);
+
+cleanup:
+  lodepng_icc_cleanup(&icc);
+  lodepng_free(data);
+  lodepng_free(gammatable);
+  return error;
+}
+
+unsigned convertToXYZFloat(float* out, float whitepoint[3], const float* in,
+                           unsigned w, unsigned h, const LodePNGState* state) {
+  unsigned error = 0;
+  const LodePNGInfo* info = &state->info_png;
+
+  unsigned use_icc = 0;
+  LodePNGICC icc;
+  lodepng_icc_init(&icc);
+  if(info->iccp_defined) {
+    error = parseICC(&icc, info->iccp_profile, info->iccp_profile_size);
+    if(error) goto cleanup; /* corrupted ICC profile */
+    use_icc = validateICC(&icc);
+  }
+  /* Input is floating point, so lookup table cannot be used, but it's ensured to
+  use float pow, not the slower double pow. */
+  convertToXYZ_gamma(out, in, w, h, info, use_icc, &icc);
+  convertToXYZ_chrm(out, w, h, info, use_icc, &icc, whitepoint);
+
+cleanup:
+  lodepng_icc_cleanup(&icc);
+  return error;
+}
+
+static unsigned convertFromXYZ_chrm(float* out, const float* in, unsigned w, unsigned h,
+                                    const LodePNGInfo* info, unsigned use_icc, const LodePNGICC* icc,
+                                    const float whitepoint[3], unsigned rendering_intent) {
+  size_t i;
+  size_t n = w * h;
+
+  float m[9]; /* XYZ to linear RGB matrix */
+  float white[3]; /* The whitepoint (absolute) of the target RGB space */
+
+  if(getChrm(m, white, use_icc, icc, info)) return 1;
+  if(invMatrix(m)) return 1; /* error, not invertible */
+
+  /* for relative rendering intent (any except absolute "3"), must whitepoint adapt to the original whitepoint.
+  this also ensures grayscale stays grayscale (with absolute, grayscale could become e.g. blue or sepia) */
+  if(rendering_intent != 3) {
+    float a[9] = {1,0,0, 0,1,0, 0,0,1};
+    /* "white" = absolute whitepoint of the new target RGB space, read from the target color profile.
+    "whitepoint" is original absolute whitepoint (input as parameter of this function) of an
+    RGB space the XYZ data once had before it was converted to XYZ, in other words the whitepoint that
+    we want to adapt our current data to to make sure values that had equal R==G==B in the old space have
+    the same property now (white stays white and gray stays gray).
+    Note: "absolute" whitepoint above means, can be used as-is, not needing further adaptation itself like icc.white does.*/
+    if(getAdaptationMatrix(a, 1, whitepoint[0], whitepoint[1], whitepoint[2], white[0], white[1], white[2])) {
+      return 1;
+    }
+    /* multiply the from xyz matrix with the adaptation matrix: in total,
+    the resulting matrix first adapts in XYZ space, then converts to RGB*/
+    mulMatrixMatrix(m, m, a);
+  }
+
+  /* Apply the above computed XYZ-to-linear-RGB matrix to the pixels.
+  This transformation also includes the whitepoint adaptation. The transform
+  can be skipped only if it's the unit matrix (only if grayscale profile and no
+  whitepoint adaptation, such as with rendering intent 3)*/
+  if(!use_icc || icc->inputspace == 2 || rendering_intent != 3) {
+    for(i = 0; i < n; i++) {
+      size_t j = i * 4;
+      mulMatrix(&out[j + 0], &out[j + 1], &out[j + 2], m, in[j + 0], in[j + 1], in[j + 2]);
+      out[j + 3] = in[j + 3];
+    }
+  } else {
+    for(i = 0; i < n * 4; i++) {
+      out[i] = in[i];
+    }
+  }
+
+  return 0;
+}
+
+/* Converts in-place. Does not clamp. */
+static void convertFromXYZ_gamma(float* im, unsigned w, unsigned h,
+                                 const LodePNGInfo* info, unsigned use_icc, const LodePNGICC* icc) {
+  size_t i, c;
+  size_t n = w * h;
+  if(use_icc) {
+    for(i = 0; i < n; i++) {
+      for(c = 0; c < 3; c++) {
+        /* TODO: this is likely very slow */
+        im[i * 4 + c] = iccBackwardTRC(&icc->trc[c], im[i * 4 + c]);
+      }
+    }
+  } else if(info->gama_defined && !info->srgb_defined) {
+    /* nothing to do if gamma is 1 */
+    if(info->gama_gamma != 100000) {
+      float gamma = info->gama_gamma / 100000.0f;
+      for(i = 0; i < n; i++) {
+        for(c = 0; c < 3; c++) {
+          if(im[i * 4 + c] > 0) im[i * 4 + c] = lodepng_powf(im[i * 4 + c], gamma);
+        }
+      }
+    }
+  } else {
+    for(i = 0; i < n; i++) {
+      for(c = 0; c < 3; c++) {
+        /* sRGB gamma compress */
+        float* v = &im[i * 4 + c];
+        *v = (*v < 0.0031308f) ? (*v * 12.92f) : (1.055f * lodepng_powf(*v, 1 / 2.4f) - 0.055f);
+      }
+    }
+  }
+}
+
+unsigned convertFromXYZ(unsigned char* out, const float* in, unsigned w, unsigned h,
+                        const LodePNGState* state,
+                        const float whitepoint[3], unsigned rendering_intent) {
+  unsigned error = 0;
+  size_t i, c;
+  size_t n = w * h;
+  const LodePNGColorMode* mode_out = &state->info_raw;
+  const LodePNGInfo* info = &state->info_png;
+  int bit16 = mode_out->bitdepth > 8;
+  float* im = 0;
+  unsigned char* data = 0;
+
+  /* parse ICC if present */
+  unsigned use_icc = 0;
+  LodePNGICC icc;
+  lodepng_icc_init(&icc);
+  if(info->iccp_defined) {
+    error = parseICC(&icc, info->iccp_profile, info->iccp_profile_size);
+    if(error) goto cleanup; /* corrupted ICC profile */
+    use_icc = validateICC(&icc);
+  }
+
+  /* Handle gamut */
+  im = (float*)lodepng_malloc(w * h * 4 * sizeof(float));
+  error = convertFromXYZ_chrm(im, in, w, h, info, use_icc, &icc, whitepoint, rendering_intent);
+  if(error) goto cleanup;
+
+  /* Handle transfer function */
+  /* Input is floating point, so lookup table cannot be used, but it's ensured to use float pow, not the slower double pow. */
+  convertFromXYZ_gamma(im, w, h, info, use_icc, &icc);
+
+  /* Convert to integer output */
+  data = (unsigned char*)lodepng_malloc(w * h * 8);
+  /* TODO: check if also 1/2/4 bit case needed: rounding is at different fine-grainedness for 8 and 16 bits below. */
+  if(bit16) {
+    LodePNGColorMode mode16 = lodepng_color_mode_make(LCT_RGBA, 16);
+    for(i = 0; i < n; i++) {
+      for(c = 0; c < 4; c++) {
+        size_t j = i * 8 + c * 2;
+        int i16 = (int)(0.5f + 65535.0f * LODEPNG_MIN(LODEPNG_MAX(0.0f, im[i * 4 + c]), 1.0f));
+        data[j + 0] = i16 >> 8;
+        data[j + 1] = i16 & 255;
+      }
+    }
+    error = lodepng_convert(out, data, mode_out, &mode16, w, h);
+    if(error) goto cleanup;
+  } else {
+    LodePNGColorMode mode8 = lodepng_color_mode_make(LCT_RGBA, 8);
+    for(i = 0; i < n; i++) {
+      for(c = 0; c < 4; c++) {
+        int i8 = (int)(0.5f + 255.0f * LODEPNG_MIN(LODEPNG_MAX(0.0f, im[i * 4 + c]), 1.0f));
+        data[i * 4 + c] = i8;
+      }
+    }
+    error = lodepng_convert(out, data, mode_out, &mode8, w, h);
+    if(error) goto cleanup;
+  }
+
+cleanup:
+  lodepng_icc_cleanup(&icc);
+  lodepng_free(im);
+  lodepng_free(data);
+  return error;
+}
+
+unsigned convertFromXYZFloat(float* out, const float* in, unsigned w, unsigned h,
+                             const LodePNGState* state,
+                             const float whitepoint[3], unsigned rendering_intent) {
+  unsigned error = 0;
+  const LodePNGInfo* info = &state->info_png;
+
+  /* parse ICC if present */
+  unsigned use_icc = 0;
+  LodePNGICC icc;
+  lodepng_icc_init(&icc);
+  if(info->iccp_defined) {
+    error = parseICC(&icc, info->iccp_profile, info->iccp_profile_size);
+    if(error) goto cleanup; /* corrupted ICC profile */
+    use_icc = validateICC(&icc);
+  }
+
+  /* Handle gamut */
+  error = convertFromXYZ_chrm(out, in, w, h, info, use_icc, &icc, whitepoint, rendering_intent);
+  if(error) goto cleanup;
+
+  /* Handle transfer function */
+  convertFromXYZ_gamma(out, w, h, info, use_icc, &icc);
+
+cleanup:
+  lodepng_icc_cleanup(&icc);
+  return error;
+}
+
+unsigned convertRGBModel(unsigned char* out, const unsigned char* in,
+                         unsigned w, unsigned h,
+                         const LodePNGState* state_out,
+                         const LodePNGState* state_in,
+                         unsigned rendering_intent) {
+  if(modelsEqual(state_in, state_out)) {
+    return lodepng_convert(out, in, &state_out->info_raw, &state_in->info_raw, w, h);
+  } else {
+    unsigned error = 0;
+    float* xyz = (float*)lodepng_malloc(w * h * 4 * sizeof(float));
+    float whitepoint[3];
+    error = convertToXYZ(&xyz[0], whitepoint, in, w, h, state_in);
+    if (!error) error = convertFromXYZ(out, &xyz[0], w, h, state_out, whitepoint, rendering_intent);
+    lodepng_free(xyz);
+    return error;
+  }
+}
+
+unsigned convertToSrgb(unsigned char* out, const unsigned char* in,
+                       unsigned w, unsigned h,
+                       const LodePNGState* state_in) {
+  LodePNGState srgb;
+  lodepng_state_init(&srgb);
+  lodepng_color_mode_copy(&srgb.info_raw, &state_in->info_raw);
+  return convertRGBModel(out, in, w, h, &srgb, state_in, 1);
+}
+
+unsigned convertFromSrgb(unsigned char* out, const unsigned char* in,
+                         unsigned w, unsigned h,
+                         const LodePNGState* state_out) {
+  LodePNGState srgb;
+  lodepng_state_init(&srgb);
+  lodepng_color_mode_copy(&srgb.info_raw, &state_out->info_raw);
+  return convertRGBModel(out, in, w, h, state_out, &srgb, 1);
+}
+
+#endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/
+
+////////////////////////////////////////////////////////////////////////////////
+
+
+
 //This uses a stripped down version of picoPNG to extract detailed zlib information while decompressing.
-static const unsigned long LENBASE[29] =
-    {3,4,5,6,7,8,9,10,11,13,15,17,19,23,27,31,35,43,51,59,67,83,99,115,131,163,195,227,258};
-static const unsigned long LENEXTRA[29] =
-    {0,0,0,0,0,0,0, 0, 1, 1, 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 4, 4, 4,  4,  5,  5,  5,  5,  0};
-static const unsigned long DISTBASE[30] =
-    {1,2,3,4,5,7,9,13,17,25,33,49,65,97,129,193,257,385,513,769,1025,1537,2049,3073,4097,6145,8193,12289,16385,24577};
-static const unsigned long DISTEXTRA[30] =
-    {0,0,0,0,1,1,2, 2, 3, 3, 4, 4, 5, 5,  6,  6,  7,  7,  8,  8,   9,   9,  10,  10,  11,  11,  12,   12,   13,   13};
-static const unsigned long CLCL[19] =
-    {16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15}; //code length code lengths
-
-struct ExtractZlib // Zlib decompression and information extraction
-{
+static const unsigned long LENBASE[29] = {3,4,5,6,7,8,9,10,11,13,15,17,19,23,27,31,35,43,51,59,67,83,99,115,131,163,195,227,258};
+static const unsigned long LENEXTRA[29] = {0,0,0,0,0,0,0, 0, 1, 1, 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 4, 4, 4,  4,  5,  5,  5,  5,  0};
+static const unsigned long DISTBASE[30] = {1,2,3,4,5,7,9,13,17,25,33,49,65,97,129,193,257,385,513,769,1025,1537,2049,3073,4097,6145,8193,12289,16385,24577};
+static const unsigned long DISTEXTRA[30] = {0,0,0,0,1,1,2, 2, 3, 3, 4, 4, 5, 5,  6,  6,  7,  7,  8,  8,   9,   9,  10,  10,  11,  11,  12,   12,   13,   13};
+static const unsigned long CLCL[19] = {16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15}; //code length code lengths
+
+struct ExtractZlib { // Zlib decompression and information extraction
   std::vector<ZlibBlockInfo>* zlibinfo;
   ExtractZlib(std::vector<ZlibBlockInfo>* info) : zlibinfo(info) {};
   int error;
 
-  unsigned long readBitFromStream(size_t& bitp, const unsigned char* bits)
-  {
+  unsigned long readBitFromStream(size_t& bitp, const unsigned char* bits) {
     unsigned long result = (bits[bitp >> 3] >> (bitp & 0x7)) & 1;
     bitp++;
     return result;
   }
 
-  unsigned long readBitsFromStream(size_t& bitp, const unsigned char* bits, size_t nbits)
-  {
+  unsigned long readBitsFromStream(size_t& bitp, const unsigned char* bits, size_t nbits) {
     unsigned long result = 0;
     for(size_t i = 0; i < nbits; i++) result += (readBitFromStream(bitp, bits)) << i;
     return result;
   }
 
-  struct HuffmanTree
-  {
-    int makeFromLengths(const std::vector<unsigned long>& bitlen, unsigned long maxbitlen)
-    { //make tree given the lengths
+  struct HuffmanTree {
+    int makeFromLengths(const std::vector<unsigned long>& bitlen, unsigned long maxbitlen) { //make tree given the lengths
       unsigned long numcodes = (unsigned long)(bitlen.size()), treepos = 0, nodefilled = 0;
       std::vector<unsigned long> tree1d(numcodes), blcount(maxbitlen + 1, 0), nextcode(maxbitlen + 1, 0);
       //count number of instances of each code length
       for(unsigned long bits = 0; bits < numcodes; bits++) blcount[bitlen[bits]]++;
-      for(unsigned long bits = 1; bits <= maxbitlen; bits++)
-      {
+      for(unsigned long bits = 1; bits <= maxbitlen; bits++) {
         nextcode[bits] = (nextcode[bits - 1] + blcount[bits - 1]) << 1;
       }
       //generate all the codes
       for(unsigned long n = 0; n < numcodes; n++) if(bitlen[n] != 0) tree1d[n] = nextcode[bitlen[n]]++;
       tree2d.clear(); tree2d.resize(numcodes * 2, 32767); //32767 here means the tree2d isn't filled there yet
       for(unsigned long n = 0; n < numcodes; n++) //the codes
-      for(unsigned long i = 0; i < bitlen[n]; i++) //the bits for this code
-      {
+      for(unsigned long i = 0; i < bitlen[n]; i++) { //the bits for this code
         unsigned long bit = (tree1d[n] >> (bitlen[n] - i - 1)) & 1;
         if(treepos > numcodes - 2) return 55;
-        if(tree2d[2 * treepos + bit] == 32767) //not yet filled in
-        {
-          if(i + 1 == bitlen[n])
-          {
+        if(tree2d[2 * treepos + bit] == 32767) { //not yet filled in
+          if(i + 1 == bitlen[n]) {
             //last bit
             tree2d[2 * treepos + bit] = n;
             treepos = 0;
-          }
-          else
-          {
+          } else {
             //addresses are encoded as values > numcodes
             tree2d[2 * treepos + bit] = ++nodefilled + numcodes;
             treepos = nodefilled;
@@ -361,8 +1485,7 @@ struct ExtractZlib // Zlib decompression and information extraction
       }
       return 0;
     }
-    int decode(bool& decoded, unsigned long& result, size_t& treepos, unsigned long bit) const
-    { //Decodes a symbol from the tree
+    int decode(bool& decoded, unsigned long& result, size_t& treepos, unsigned long bit) const { //Decodes a symbol from the tree
       unsigned long numcodes = (unsigned long)tree2d.size() / 2;
       if(treepos >= numcodes) return 11; //error: you appeared outside the codetree
       result = tree2d[2 * treepos + bit];
@@ -374,13 +1497,11 @@ struct ExtractZlib // Zlib decompression and information extraction
     std::vector<unsigned long> tree2d;
   };
 
-  void inflate(std::vector<unsigned char>& out, const std::vector<unsigned char>& in, size_t inpos = 0)
-  {
+  void inflate(std::vector<unsigned char>& out, const std::vector<unsigned char>& in, size_t inpos = 0) {
     size_t bp = 0, pos = 0; //bit pointer and byte pointer
     error = 0;
     unsigned long BFINAL = 0;
-    while(!BFINAL && !error)
-    {
+    while(!BFINAL && !error) {
       size_t uncomprblockstart = pos;
       size_t bpstart = bp;
       if(bp >> 3 >= in.size()) { error = 52; return; } //error, bit pointer will jump past memory
@@ -397,8 +1518,7 @@ struct ExtractZlib // Zlib decompression and information extraction
     }
   }
 
-  void generateFixedTrees(HuffmanTree& tree, HuffmanTree& treeD) //get the tree of a deflated block with fixed tree
-  {
+  void generateFixedTrees(HuffmanTree& tree, HuffmanTree& treeD) { //get the tree of a deflated block with fixed tree
     std::vector<unsigned long> bitlen(288, 8), bitlenD(32, 5);;
     for(size_t i = 144; i <= 255; i++) bitlen[i] = 9;
     for(size_t i = 256; i <= 279; i++) bitlen[i] = 7;
@@ -408,12 +1528,10 @@ struct ExtractZlib // Zlib decompression and information extraction
 
   //the code tree for Huffman codes, dist codes, and code length codes
   HuffmanTree codetree, codetreeD, codelengthcodetree;
-  unsigned long huffmanDecodeSymbol(const unsigned char* in, size_t& bp, const HuffmanTree& tree, size_t inlength)
-  {
+  unsigned long huffmanDecodeSymbol(const unsigned char* in, size_t& bp, const HuffmanTree& tree, size_t inlength) {
     //decode a single symbol from given list of bits with given code tree. return value is the symbol
     bool decoded; unsigned long ct;
-    for(size_t treepos = 0;;)
-    {
+    for(size_t treepos = 0;;) {
       if((bp & 0x07) == 0 && (bp >> 3) > inlength) { error = 10; return 0; } //error: end reached without endcode
       error = tree.decode(decoded, ct, treepos, readBitFromStream(bp, in));
       if(error) return 0; //stop, an error happened
@@ -422,8 +1540,7 @@ struct ExtractZlib // Zlib decompression and information extraction
   }
 
   void getTreeInflateDynamic(HuffmanTree& tree, HuffmanTree& treeD,
-                             const unsigned char* in, size_t& bp, size_t inlength)
-  {
+                             const unsigned char* in, size_t& bp, size_t inlength) {
     size_t bpstart = bp;
     //get the tree of a deflated block with dynamic tree, the tree itself is also Huffman compressed with a known tree
     std::vector<unsigned long> bitlen(288, 0), bitlenD(32, 0);
@@ -440,42 +1557,33 @@ struct ExtractZlib // Zlib decompression and information extraction
     for(size_t i = 0; i < codelengthcode.size(); i++) zlibinfo->back().clcl.push_back(codelengthcode[i]);
     error = codelengthcodetree.makeFromLengths(codelengthcode, 7); if(error) return;
     size_t i = 0, replength;
-    while(i < HLIT + HDIST)
-    {
+    while(i < HLIT + HDIST) {
       unsigned long code = huffmanDecodeSymbol(in, bp, codelengthcodetree, inlength); if(error) return;
       zlibinfo->back().treecodes.push_back(code); //tree symbol code
       if(code <= 15)  { if(i < HLIT) bitlen[i++] = code; else bitlenD[i++ - HLIT] = code; } //a length code
-      else if(code == 16) //repeat previous
-      {
+      else if(code == 16) { //repeat previous
         if(bp >> 3 >= inlength) { error = 50; return; } //error, bit pointer jumps past memory
         replength = 3 + readBitsFromStream(bp, in, 2);
         unsigned long value; //set value to the previous code
         if((i - 1) < HLIT) value = bitlen[i - 1];
         else value = bitlenD[i - HLIT - 1];
-        for(size_t n = 0; n < replength; n++) //repeat this value in the next lengths
-        {
+        for(size_t n = 0; n < replength; n++) { //repeat this value in the next lengths
           if(i >= HLIT + HDIST) { error = 13; return; } //error: i is larger than the amount of codes
           if(i < HLIT) bitlen[i++] = value; else bitlenD[i++ - HLIT] = value;
         }
-      }
-      else if(code == 17) //repeat "0" 3-10 times
-      {
+      } else if(code == 17) { //repeat "0" 3-10 times
         if(bp >> 3 >= inlength) { error = 50; return; } //error, bit pointer jumps past memory
         replength = 3 + readBitsFromStream(bp, in, 3);
         zlibinfo->back().treecodes.push_back(replength); //tree symbol code repetitions
-        for(size_t n = 0; n < replength; n++) //repeat this value in the next lengths
-        {
+        for(size_t n = 0; n < replength; n++) { //repeat this value in the next lengths
           if(i >= HLIT + HDIST) { error = 14; return; } //error: i is larger than the amount of codes
           if(i < HLIT) bitlen[i++] = 0; else bitlenD[i++ - HLIT] = 0;
         }
-      }
-      else if(code == 18) //repeat "0" 11-138 times
-      {
+      } else if(code == 18) { //repeat "0" 11-138 times
         if(bp >> 3 >= inlength) { error = 50; return; } //error, bit pointer jumps past memory
         replength = 11 + readBitsFromStream(bp, in, 7);
         zlibinfo->back().treecodes.push_back(replength); //tree symbol code repetitions
-        for(size_t n = 0; n < replength; n++) //repeat this value in the next lengths
-        {
+        for(size_t n = 0; n < replength; n++) { //repeat this value in the next lengths
           if(i >= HLIT + HDIST) { error = 15; return; } //error: i is larger than the amount of codes
           if(i < HLIT) bitlen[i++] = 0; else bitlenD[i++ - HLIT] = 0;
         }
@@ -495,13 +1603,11 @@ struct ExtractZlib // Zlib decompression and information extraction
   }
 
   void inflateHuffmanBlock(std::vector<unsigned char>& out,
-                           const unsigned char* in, size_t& bp, size_t& pos, size_t inlength, unsigned long btype)
-  {
+                           const unsigned char* in, size_t& bp, size_t& pos, size_t inlength, unsigned long btype) {
     size_t numcodes = 0, numlit = 0, numlen = 0; //for logging
     if(btype == 1) { generateFixedTrees(codetree, codetreeD); }
     else if(btype == 2) { getTreeInflateDynamic(codetree, codetreeD, in, bp, inlength); if(error) return; }
-    for(;;)
-    {
+    for(;;) {
       unsigned long code = huffmanDecodeSymbol(in, bp, codetree, inlength); if(error) return;
       numcodes++;
       zlibinfo->back().lz77_lcode.push_back(code); //output code
@@ -511,15 +1617,13 @@ struct ExtractZlib // Zlib decompression and information extraction
       zlibinfo->back().lz77_lvalue.push_back(0);
       zlibinfo->back().lz77_dvalue.push_back(0);
 
-      if(code == 256) break; //end code
-      else if(code <= 255) //literal symbol
-      {
+      if(code == 256) {
+        break; //end code
+      } else if(code <= 255) { //literal symbol
         out.push_back((unsigned char)(code));
         pos++;
         numlit++;
-      }
-      else if(code >= 257 && code <= 285) //length code
-      {
+      } else if(code >= 257 && code <= 285) { //length code
         size_t length = LENBASE[code - 257], numextrabits = LENEXTRA[code - 257];
         if((bp >> 3) >= inlength) { error = 51; return; } //error, bit pointer will jump past memory
         length += readBitsFromStream(bp, in, numextrabits);
@@ -529,8 +1633,7 @@ struct ExtractZlib // Zlib decompression and information extraction
         if((bp >> 3) >= inlength) { error = 51; return; } //error, bit pointer will jump past memory
         dist += readBitsFromStream(bp, in, numextrabitsD);
         size_t start = pos, back = start - dist; //backwards
-        for(size_t i = 0; i < length; i++)
-        {
+        for(size_t i = 0; i < length; i++) {
           out.push_back(out[back++]);
           pos++;
           if(back >= start) back = start - dist;
@@ -548,24 +1651,21 @@ struct ExtractZlib // Zlib decompression and information extraction
   }
 
   void inflateNoCompression(std::vector<unsigned char>& out,
-                            const unsigned char* in, size_t& bp, size_t& pos, size_t inlength)
-  {
+                            const unsigned char* in, size_t& bp, size_t& pos, size_t inlength) {
     while((bp & 0x7) != 0) bp++; //go to first boundary of byte
     size_t p = bp / 8;
     if(p >= inlength - 4) { error = 52; return; } //error, bit pointer will jump past memory
     unsigned long LEN = in[p] + 256u * in[p + 1], NLEN = in[p + 2] + 256u * in[p + 3]; p += 4;
     if(LEN + NLEN != 65535) { error = 21; return; } //error: NLEN is not one's complement of LEN
     if(p + LEN > inlength) { error = 23; return; } //error: reading outside of in buffer
-    for(unsigned long n = 0; n < LEN; n++)
-    {
+    for(unsigned long n = 0; n < LEN; n++) {
       out.push_back(in[p++]); //read LEN bytes of literal data
       pos++;
     }
     bp = p * 8;
   }
 
-  int decompress(std::vector<unsigned char>& out, const std::vector<unsigned char>& in) //returns error value
-  {
+  int decompress(std::vector<unsigned char>& out, const std::vector<unsigned char>& in) { //returns error value
     if(in.size() < 2) { return 53; } //error, size of zlib data too small
     //error: 256 * in[0] + in[1] must be a multiple of 31, the FCHECK value is supposed to be made that way
     if((in[0] * 256 + in[1]) % 31 != 0) { return 24; }
@@ -579,13 +1679,11 @@ struct ExtractZlib // Zlib decompression and information extraction
   }
 };
 
-struct ExtractPNG //PNG decoding and information extraction
-{
+struct ExtractPNG { //PNG decoding and information extraction
   std::vector<ZlibBlockInfo>* zlibinfo;
   ExtractPNG(std::vector<ZlibBlockInfo>* info) : zlibinfo(info) {};
   int error;
-  void decode(const unsigned char* in, size_t size)
-  {
+  void decode(const unsigned char* in, size_t size) {
     error = 0;
     if(size == 0 || in == 0) { error = 48; return; } //the given data is empty
     readPngHeader(&in[0], size); if(error) return;
@@ -594,8 +1692,7 @@ struct ExtractPNG //PNG decoding and information extraction
     bool IEND = false;
     //loop through the chunks, ignoring unknown chunks and stopping at IEND chunk.
     //IDAT data is put at the start of the in buffer
-    while(!IEND)
-    {
+    while(!IEND) {
       //error: size of the in buffer too small to contain next chunk
       if(pos + 8 >= size) { error = 30; return; }
       size_t chunkLength = read32bitInt(&in[pos]); pos += 4;
@@ -603,18 +1700,13 @@ struct ExtractPNG //PNG decoding and information extraction
       //error: size of the in buffer too small to contain next chunk
       if(pos + chunkLength >= size) { error = 35; return; }
       //IDAT chunk, containing compressed image data
-      if(in[pos + 0] == 'I' && in[pos + 1] == 'D' && in[pos + 2] == 'A' && in[pos + 3] == 'T')
-      {
+      if(in[pos + 0] == 'I' && in[pos + 1] == 'D' && in[pos + 2] == 'A' && in[pos + 3] == 'T') {
         idat.insert(idat.end(), &in[pos + 4], &in[pos + 4 + chunkLength]);
         pos += (4 + chunkLength);
-      }
-      else if(in[pos + 0] == 'I' && in[pos + 1] == 'E' && in[pos + 2] == 'N' && in[pos + 3] == 'D')
-      {
+      } else if(in[pos + 0] == 'I' && in[pos + 1] == 'E' && in[pos + 2] == 'N' && in[pos + 3] == 'D') {
           pos += 4;
           IEND = true;
-      }
-      else //it's not an implemented chunk type, so ignore it: skip over the data
-      {
+      } else { //it's not an implemented chunk type, so ignore it: skip over the data
         pos += (chunkLength + 4); //skip 4 letters and uninterpreted data of unimplemented chunk
       }
       pos += 4; //step over CRC (which is ignored)
@@ -626,8 +1718,7 @@ struct ExtractPNG //PNG decoding and information extraction
   }
 
   //read the information from the header and store it in the Info
-  void readPngHeader(const unsigned char* in, size_t inlength)
-  {
+  void readPngHeader(const unsigned char* in, size_t inlength) {
     if(inlength < 29) { error = 27; return; } //error: the data length is smaller than the length of the header
     if(in[0] != 137 || in[1] != 80 || in[2] != 78 || in[3] != 71
     || in[4] != 13 || in[5] != 10 || in[6] != 26 || in[7] != 10) { error = 28; return; } //no PNG signature
@@ -635,33 +1726,28 @@ struct ExtractPNG //PNG decoding and information extraction
     if(in[12] != 'I' || in[13] != 'H' || in[14] != 'D' || in[15] != 'R') { error = 29; return; }
   }
 
-  unsigned long readBitFromReversedStream(size_t& bitp, const unsigned char* bits)
-  {
+  unsigned long readBitFromReversedStream(size_t& bitp, const unsigned char* bits) {
     unsigned long result = (bits[bitp >> 3] >> (7 - (bitp & 0x7))) & 1;
     bitp++;
     return result;
   }
 
-  unsigned long readBitsFromReversedStream(size_t& bitp, const unsigned char* bits, unsigned long nbits)
-  {
+  unsigned long readBitsFromReversedStream(size_t& bitp, const unsigned char* bits, unsigned long nbits) {
     unsigned long result = 0;
     for(size_t i = nbits - 1; i < nbits; i--) result += ((readBitFromReversedStream(bitp, bits)) << i);
     return result;
   }
 
-  void setBitOfReversedStream(size_t& bitp, unsigned char* bits, unsigned long bit)
-  {
+  void setBitOfReversedStream(size_t& bitp, unsigned char* bits, unsigned long bit) {
     bits[bitp >> 3] |=  (bit << (7 - (bitp & 0x7))); bitp++;
   }
 
-  unsigned long read32bitInt(const unsigned char* buffer)
-  {
+  unsigned long read32bitInt(const unsigned char* buffer) {
     return (unsigned int)((buffer[0] << 24u) | (buffer[1] << 16u) | (buffer[2] << 8u) | buffer[3]);
   }
 };
 
-void extractZlibInfo(std::vector<ZlibBlockInfo>& zlibinfo, const std::vector<unsigned char>& in)
-{
+void extractZlibInfo(std::vector<ZlibBlockInfo>& zlibinfo, const std::vector<unsigned char>& in) {
   ExtractPNG decoder(&zlibinfo);
   decoder.decode(&in[0], in.size());
 
diff --git a/src/zopflipng/lodepng/lodepng_util.h b/src/zopflipng/lodepng/lodepng_util.h
index e74bbb5..514b51c 100644
--- a/src/zopflipng/lodepng/lodepng_util.h
+++ b/src/zopflipng/lodepng/lodepng_util.h
@@ -1,7 +1,7 @@
 /*
 LodePNG Utils
 
-Copyright (c) 2005-2014 Lode Vandevenne
+Copyright (c) 2005-2019 Lode Vandevenne
 
 This software is provided 'as-is', without any express or implied
 warranty. In no event will the authors be held liable for any damages
@@ -25,16 +25,17 @@ freely, subject to the following restrictions:
 
 /*
 Extra C++ utilities for LodePNG, for convenience.
+Not part of the stable API of lodepng, more loose separate utils.
 */
 
+#ifndef LODEPNG_UTIL_H
+#define LODEPNG_UTIL_H
+
 #include <string>
 #include <vector>
 #include "lodepng.h"
 
-#pragma once
-
-namespace lodepng
-{
+namespace lodepng {
 
 /*
 Returns info from the header of the PNG by value, purely for convenience.
@@ -114,11 +115,147 @@ is the second half of the 3th byte, in big endian (PNG's endian order).
 */
 int getPaletteValue(const unsigned char* data, size_t i, int bits);
 
+#ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS
+
+/* Similar to convertRGBModel, but the 'to' model is sRGB. The pixel format
+of in and out must be the same and is given by state_in->info_raw. An
+error may occur if the pixel format cannot contain the new colors (e.g. palette) */
+unsigned convertToSrgb(unsigned char* out, const unsigned char* in,
+                       unsigned w, unsigned h,
+                       const LodePNGState* state_in);
+
+/* Similar to convertRGBModel, but the 'from' model is sRGB. The pixel format
+of in and out must be the same and is given by state_out->info_raw. An
+error may occur if the pixel format cannot contain the new colors (e.g. palette) */
+unsigned convertFromSrgb(unsigned char* out, const unsigned char* in,
+                         unsigned w, unsigned h,
+                         const LodePNGState* state_out);
+
+/*
+Converts from one RGB model to another RGB model.
+Similar to calling convertToXYZ followed by convertFromXYZ, but may be
+more efficient and more precise (e.g. no computation needed when both models
+are the same). See their documentation for more info.
+
+Parameters:
+
+*) out: output pixel data
+*) in: input pixel data
+*) w, h: image size
+*) state_out: output RGB color model in state_out->info_png and byte format in state_out->info_raw.
+*) state_in: output RGB color model in state_in->info_png and byte format in state_in->info_raw
+*) return value: 0 if ok, positive value if error
+*) rendering_intent: 1 for relative, 3 for absolute, should be relative for standard behavior.
+   See description at convertFromXYZ.
+*/
+unsigned convertRGBModel(unsigned char* out, const unsigned char* in,
+                         unsigned w, unsigned h,
+                         const LodePNGState* state_out,
+                         const LodePNGState* state_in,
+                         unsigned rendering_intent);
+
+/*
+Converts the RGB color to the absolute XYZ color space given the RGB color profile
+chunks in the PNG info.
+
+Color space here refers to the different possible RGB spaces with different
+possible chromaticities or whitepoint and XYZ color from colorimetry, not the
+LodePNGColorType that describes the byte based encoding.
+
+You need this function only if the PNG could contain data in an arbitrary RGB
+color space and you wish to output to a display or format that does not provide
+color management for you (so you need to convert rather than pass on the profile
+to it) but expects a certain RGB format (e.g. sRGB). See the background info below.
+
+Supports the gAMA, cHRM, sRGB and iCCP colorimetry chunks. If no colometry chunks are present
+(that is, in state->info_png, the fields gama_defined, chrm_defined, srgb_defined and
+iccp_defined are all 0), it assumes the format is sRGB.
+For more information, see the chunk specifications in the PNG specification.
+
+Some background:
+
+A PNG image contains RGB data inside, but this data may use a specific RGB model (by default sRGB but
+different if colorimetry chunks are given).
+The computer display and/or operating system can have another RGB model (typically sRGB, or wider gamut
+or HDR formats).
+
+The PNG chunks describe what format the data inside has, not the format of the display. To correctly
+display a PNG image on a display, a conversion is needed from the PNG model to the display model if their
+models differ. Some options to achieve that are:
+*) If your use case already supports color management on its own, you can give it the RGB values straight from
+   the PNG image and give it the information from the cHRM, gAMA, sRGB and iCCP chunks (which you can find
+   in the LodePNGInfo), and the color management should then handle it correctly for you. You don't need
+   this function here in that case.
+*) If your use case does not support color management, you may instead want to give it the RGB values in a
+   consistent color model, such as sRGB, but the PNG does not necessarily have it in this desired model.
+   In that case, use the function below (or a similar one from a CMS library if you prefer) to convert it to
+   the absolute color space XYZ, and then you can convert it to the target RGB with the counterpart convertFromXYZ
+   further below.
+
+Parameters:
+
+*) out: 4 floats per pixel, X,Y,Z,alpha color format, in range 0-1 (normally, not clipped if beyond), must
+   be allocated to have 4 * w * h floats available.
+*) whitepoint: output argument, the whitepoint the original RGB data used, given in absolute XYZ. Needed for
+   relative rendering intents: give these values to counterpart function convertFromXYZ.
+*) in: input RGB color, in byte format given by state->info_raw and RGB color profile given by info->info_png
+*) w, h: image size
+*) state (when using a LodePNG decode function that takes a LodePNGState parameter, can directly use that one):
+   state->info_png: PNG info with possibly an RGB color model in cHRM,gAMA and/or sRGB chunks
+   state->info_raw: byte format of in (amount of channels, bit depth)
+*) return value: 0 if ok, positive value if error
+*/
+unsigned convertToXYZ(float* out, float whitepoint[3],
+                      const unsigned char* in, unsigned w, unsigned h,
+                      const LodePNGState* state);
+
+/*
+Same as convertToXYZ but takes floating point input. Slower.
+The main black..white range in 0..1. Does not clip values that are outside that range.
+*/
+unsigned convertToXYZFloat(float* out, float whitepoint[3], const float* in,
+                           unsigned w, unsigned h, const LodePNGState* state);
+
+/*
+Converts XYZ to RGB in the RGB color model given by info and byte format by mode_out.
+If info has no coloremtry chunks, converts to sRGB.
+Parameters:
+*) out: output color in byte format given by state->info_raw and RGB color profile given
+   by info->info_png. Must have enough bytes allocated to contain pixels in the given byte format.
+*) in: 4 floats per pixel, X,Y,Z,alpha color format, in range 0-1 (normally).
+*) whitepoint: input argument, the original whitepoint in absolute XYZ that the pixel data
+   in "in" had back when it was in a previous RGB space. Needed to preserve the whitepoint
+   in the new target RGB space for relative rendering intent.
+*) rendering_intent: the desired rendering intent, with numeric meaning matching the
+   values used by ICC: 0=perceptual, 1=relative, 2=saturation, 3=absolute.
+   Should be 1 for normal use cases, it adapts white to match that of different RGB
+   models which is the best practice. Using 3 may change the color of white and may
+   turn grayscale into colors of a certain tone. Using 0 and 2 will have the same
+   effect as 1 because using those requires more data than the matrix-based RGB profiles
+   supporetd here have.
+*) w, h: image size
+*) state:
+   state->info_png: PNG info with possibly an RGB color profile in cHRM,gAMA and/or sRGB chunks
+   state->info_raw: byte format of out (amount of channels, bit depth)
+*) return value: 0 if ok, positive value if error
+*/
+unsigned convertFromXYZ(unsigned char* out, const float* in, unsigned w, unsigned h,
+                        const LodePNGState* state,
+                        const float whitepoint[3], unsigned rendering_intent);
+
+/*
+Same as convertFromXYZ but outputs the RGB colors in floating point.
+The main black..white range in 0..1. Does not clip values that are outside that range.
+*/
+unsigned convertFromXYZFloat(float* out, const float* in, unsigned w, unsigned h,
+                             const LodePNGState* state,
+                             const float whitepoint[3], unsigned rendering_intent);
+#endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/
+
 /*
 The information for extractZlibInfo.
 */
-struct ZlibBlockInfo
-{
+struct ZlibBlockInfo {
   int btype; //block type (0-2)
   size_t compressedbits; //size of compressed block in bits
   size_t uncompressedbytes; //size of uncompressed block in bytes
@@ -149,3 +286,5 @@ struct ZlibBlockInfo
 void extractZlibInfo(std::vector<ZlibBlockInfo>& zlibinfo, const std::vector<unsigned char>& in);
 
 } // namespace lodepng
+
+#endif /*LODEPNG_UTIL_H inclusion guard*/
diff --git a/src/zopflipng/zopflipng_lib.cc b/src/zopflipng/zopflipng_lib.cc
index b93bb18..811f8a4 100644
--- a/src/zopflipng/zopflipng_lib.cc
+++ b/src/zopflipng/zopflipng_lib.cc
@@ -233,20 +233,20 @@ unsigned TryOptimize(
     std::vector<unsigned char> temp;
     lodepng::decode(temp, w, h, teststate, *out);
     if (teststate.info_png.color.colortype == LCT_PALETTE) {
-      LodePNGColorProfile profile;
-      lodepng_color_profile_init(&profile);
-      lodepng_get_color_profile(&profile, &image[0], w, h, &state.info_raw);
+      LodePNGColorStats stats;
+      lodepng_color_stats_init(&stats);
+      lodepng_compute_color_stats(&stats, &image[0], w, h, &state.info_raw);
       // Too small for tRNS chunk overhead.
-      if (w * h <= 16 && profile.key) profile.alpha = 1;
+      if (w * h <= 16 && stats.key) stats.alpha = 1;
       state.encoder.auto_convert = 0;
-      state.info_png.color.colortype = (profile.alpha ? LCT_RGBA : LCT_RGB);
+      state.info_png.color.colortype = (stats.alpha ? LCT_RGBA : LCT_RGB);
       state.info_png.color.bitdepth = 8;
-      state.info_png.color.key_defined = (profile.key && !profile.alpha);
+      state.info_png.color.key_defined = (stats.key && !stats.alpha);
       if (state.info_png.color.key_defined) {
         state.info_png.color.key_defined = 1;
-        state.info_png.color.key_r = (profile.key_r & 255u);
-        state.info_png.color.key_g = (profile.key_g & 255u);
-        state.info_png.color.key_b = (profile.key_b & 255u);
+        state.info_png.color.key_r = (stats.key_r & 255u);
+        state.info_png.color.key_g = (stats.key_g & 255u);
+        state.info_png.color.key_b = (stats.key_b & 255u);
       }
 
       std::vector<unsigned char> out2;