diff options
Diffstat (limited to 'src/zopflipng/lodepng/lodepng_util.h')
| -rw-r--r-- | src/zopflipng/lodepng/lodepng_util.h | 153 |
1 files changed, 146 insertions, 7 deletions
diff --git a/src/zopflipng/lodepng/lodepng_util.h b/src/zopflipng/lodepng/lodepng_util.h index b18ac71..97fd804 100644 --- a/src/zopflipng/lodepng/lodepng_util.h +++ b/src/zopflipng/lodepng/lodepng_util.h @@ -1,7 +1,7 @@ /* LodePNG Utils -Copyright (c) 2005-2012 Lode Vandevenne +Copyright (c) 2005-2020 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*/ |