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+/*
+ * Copyright 2022 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef ULTRAHDR_GAINMAPMATH_H
+#define ULTRAHDR_GAINMAPMATH_H
+
+#include <cmath>
+
+#include "ultrahdr.h"
+#include "jpegr.h"
+
+#define CLIP3(x, min, max) ((x) < (min)) ? (min) : ((x) > (max)) ? (max) : (x)
+
+namespace ultrahdr {
+
+////////////////////////////////////////////////////////////////////////////////
+// Framework
+
+const float kSdrWhiteNits = 100.0f;
+const float kHlgMaxNits = 1000.0f;
+const float kPqMaxNits = 10000.0f;
+
+struct Color {
+ union {
+ struct {
+ float r;
+ float g;
+ float b;
+ };
+ struct {
+ float y;
+ float u;
+ float v;
+ };
+ };
+};
+
+typedef Color (*ColorTransformFn)(Color);
+typedef float (*ColorCalculationFn)(Color);
+
+// A transfer function mapping encoded values to linear values,
+// represented by this 7-parameter piecewise function:
+//
+// linear = sign(encoded) * (c*|encoded| + f) , 0 <= |encoded| < d
+// = sign(encoded) * ((a*|encoded| + b)^g + e), d <= |encoded|
+//
+// (A simple gamma transfer function sets g to gamma and a to 1.)
+typedef struct TransferFunction {
+ float g, a, b, c, d, e, f;
+} TransferFunction;
+
+static constexpr TransferFunction kSRGB_TransFun = {
+ 2.4f, (float)(1 / 1.055), (float)(0.055 / 1.055), (float)(1 / 12.92), 0.04045f, 0.0f, 0.0f};
+
+static constexpr TransferFunction kLinear_TransFun = {1.0f, 1.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f};
+
+inline Color operator+=(Color& lhs, const Color& rhs) {
+ lhs.r += rhs.r;
+ lhs.g += rhs.g;
+ lhs.b += rhs.b;
+ return lhs;
+}
+inline Color operator-=(Color& lhs, const Color& rhs) {
+ lhs.r -= rhs.r;
+ lhs.g -= rhs.g;
+ lhs.b -= rhs.b;
+ return lhs;
+}
+
+inline Color operator+(const Color& lhs, const Color& rhs) {
+ Color temp = lhs;
+ return temp += rhs;
+}
+inline Color operator-(const Color& lhs, const Color& rhs) {
+ Color temp = lhs;
+ return temp -= rhs;
+}
+
+inline Color operator+=(Color& lhs, const float rhs) {
+ lhs.r += rhs;
+ lhs.g += rhs;
+ lhs.b += rhs;
+ return lhs;
+}
+inline Color operator-=(Color& lhs, const float rhs) {
+ lhs.r -= rhs;
+ lhs.g -= rhs;
+ lhs.b -= rhs;
+ return lhs;
+}
+inline Color operator*=(Color& lhs, const float rhs) {
+ lhs.r *= rhs;
+ lhs.g *= rhs;
+ lhs.b *= rhs;
+ return lhs;
+}
+inline Color operator/=(Color& lhs, const float rhs) {
+ lhs.r /= rhs;
+ lhs.g /= rhs;
+ lhs.b /= rhs;
+ return lhs;
+}
+
+inline Color operator+(const Color& lhs, const float rhs) {
+ Color temp = lhs;
+ return temp += rhs;
+}
+inline Color operator-(const Color& lhs, const float rhs) {
+ Color temp = lhs;
+ return temp -= rhs;
+}
+inline Color operator*(const Color& lhs, const float rhs) {
+ Color temp = lhs;
+ return temp *= rhs;
+}
+inline Color operator/(const Color& lhs, const float rhs) {
+ Color temp = lhs;
+ return temp /= rhs;
+}
+
+inline uint16_t floatToHalf(float f) {
+ // round-to-nearest-even: add last bit after truncated mantissa
+ const uint32_t b = *((uint32_t*)&f) + 0x00001000;
+
+ const int32_t e = (b & 0x7F800000) >> 23; // exponent
+ const uint32_t m = b & 0x007FFFFF; // mantissa
+
+ // sign : normalized : denormalized : saturate
+ return (b & 0x80000000) >> 16 | (e > 112) * ((((e - 112) << 10) & 0x7C00) | m >> 13) |
+ ((e < 113) & (e > 101)) * ((((0x007FF000 + m) >> (125 - e)) + 1) >> 1) |
+ (e > 143) * 0x7FFF;
+}
+
+constexpr size_t kGainFactorPrecision = 10;
+constexpr size_t kGainFactorNumEntries = 1 << kGainFactorPrecision;
+struct GainLUT {
+ GainLUT(ultrahdr_metadata_ptr metadata) {
+ for (size_t idx = 0; idx < kGainFactorNumEntries; idx++) {
+ float value = static_cast<float>(idx) / static_cast<float>(kGainFactorNumEntries - 1);
+ float logBoost = log2(metadata->minContentBoost) * (1.0f - value) +
+ log2(metadata->maxContentBoost) * value;
+ mGainTable[idx] = exp2(logBoost);
+ }
+ }
+
+ GainLUT(ultrahdr_metadata_ptr metadata, float displayBoost) {
+ float boostFactor = displayBoost > 0 ? displayBoost / metadata->maxContentBoost : 1.0f;
+ for (size_t idx = 0; idx < kGainFactorNumEntries; idx++) {
+ float value = static_cast<float>(idx) / static_cast<float>(kGainFactorNumEntries - 1);
+ float logBoost = log2(metadata->minContentBoost) * (1.0f - value) +
+ log2(metadata->maxContentBoost) * value;
+ mGainTable[idx] = exp2(logBoost * boostFactor);
+ }
+ }
+
+ ~GainLUT() {}
+
+ float getGainFactor(float gain) {
+ uint32_t idx = static_cast<uint32_t>(gain * (kGainFactorNumEntries - 1) + 0.5);
+ // TODO() : Remove once conversion modules have appropriate clamping in place
+ idx = CLIP3(idx, 0, kGainFactorNumEntries - 1);
+ return mGainTable[idx];
+ }
+
+ private:
+ float mGainTable[kGainFactorNumEntries];
+};
+
+struct ShepardsIDW {
+ ShepardsIDW(int mapScaleFactor) : mMapScaleFactor{mapScaleFactor} {
+ const int size = mMapScaleFactor * mMapScaleFactor * 4;
+ mWeights = new float[size];
+ mWeightsNR = new float[size];
+ mWeightsNB = new float[size];
+ mWeightsC = new float[size];
+ fillShepardsIDW(mWeights, 1, 1);
+ fillShepardsIDW(mWeightsNR, 0, 1);
+ fillShepardsIDW(mWeightsNB, 1, 0);
+ fillShepardsIDW(mWeightsC, 0, 0);
+ }
+ ~ShepardsIDW() {
+ delete[] mWeights;
+ delete[] mWeightsNR;
+ delete[] mWeightsNB;
+ delete[] mWeightsC;
+ }
+
+ int mMapScaleFactor;
+ // Image :-
+ // p00 p01 p02 p03 p04 p05 p06 p07
+ // p10 p11 p12 p13 p14 p15 p16 p17
+ // p20 p21 p22 p23 p24 p25 p26 p27
+ // p30 p31 p32 p33 p34 p35 p36 p37
+ // p40 p41 p42 p43 p44 p45 p46 p47
+ // p50 p51 p52 p53 p54 p55 p56 p57
+ // p60 p61 p62 p63 p64 p65 p66 p67
+ // p70 p71 p72 p73 p74 p75 p76 p77
+
+ // Gain Map (for 4 scale factor) :-
+ // m00 p01
+ // m10 m11
+
+ // Gain sample of curr 4x4, right 4x4, bottom 4x4, bottom right 4x4 are used during
+ // reconstruction. hence table weight size is 4.
+ float* mWeights;
+ // TODO: check if its ok to mWeights at places
+ float* mWeightsNR; // no right
+ float* mWeightsNB; // no bottom
+ float* mWeightsC; // no right & bottom
+
+ float euclideanDistance(float x1, float x2, float y1, float y2);
+ void fillShepardsIDW(float* weights, int incR, int incB);
+};
+
+////////////////////////////////////////////////////////////////////////////////
+// sRGB transformations
+// NOTE: sRGB has the same color primaries as BT.709, but different transfer
+// function. For this reason, all sRGB transformations here apply to BT.709,
+// except for those concerning transfer functions.
+
+/*
+ * Calculate the luminance of a linear RGB sRGB pixel, according to
+ * IEC 61966-2-1/Amd 1:2003.
+ *
+ * [0.0, 1.0] range in and out.
+ */
+float srgbLuminance(Color e);
+
+/*
+ * Convert from OETF'd srgb RGB to YUV, according to ITU-R BT.709-6.
+ *
+ * BT.709 YUV<->RGB matrix is used to match expectations for DataSpace.
+ */
+Color srgbRgbToYuv(Color e_gamma);
+
+/*
+ * Convert from OETF'd srgb YUV to RGB, according to ITU-R BT.709-6.
+ *
+ * BT.709 YUV<->RGB matrix is used to match expectations for DataSpace.
+ */
+Color srgbYuvToRgb(Color e_gamma);
+
+/*
+ * Convert from srgb to linear, according to IEC 61966-2-1/Amd 1:2003.
+ *
+ * [0.0, 1.0] range in and out.
+ */
+float srgbInvOetf(float e_gamma);
+Color srgbInvOetf(Color e_gamma);
+float srgbInvOetfLUT(float e_gamma);
+Color srgbInvOetfLUT(Color e_gamma);
+
+constexpr size_t kSrgbInvOETFPrecision = 10;
+constexpr size_t kSrgbInvOETFNumEntries = 1 << kSrgbInvOETFPrecision;
+
+////////////////////////////////////////////////////////////////////////////////
+// Display-P3 transformations
+
+/*
+ * Calculated the luminance of a linear RGB P3 pixel, according to SMPTE EG 432-1.
+ *
+ * [0.0, 1.0] range in and out.
+ */
+float p3Luminance(Color e);
+
+/*
+ * Convert from OETF'd P3 RGB to YUV, according to ITU-R BT.601-7.
+ *
+ * BT.601 YUV<->RGB matrix is used to match expectations for DataSpace.
+ */
+Color p3RgbToYuv(Color e_gamma);
+
+/*
+ * Convert from OETF'd P3 YUV to RGB, according to ITU-R BT.601-7.
+ *
+ * BT.601 YUV<->RGB matrix is used to match expectations for DataSpace.
+ */
+Color p3YuvToRgb(Color e_gamma);
+
+////////////////////////////////////////////////////////////////////////////////
+// BT.2100 transformations - according to ITU-R BT.2100-2
+
+/*
+ * Calculate the luminance of a linear RGB BT.2100 pixel.
+ *
+ * [0.0, 1.0] range in and out.
+ */
+float bt2100Luminance(Color e);
+
+/*
+ * Convert from OETF'd BT.2100 RGB to YUV, according to ITU-R BT.2100-2.
+ *
+ * BT.2100 YUV<->RGB matrix is used to match expectations for DataSpace.
+ */
+Color bt2100RgbToYuv(Color e_gamma);
+
+/*
+ * Convert from OETF'd BT.2100 YUV to RGB, according to ITU-R BT.2100-2.
+ *
+ * BT.2100 YUV<->RGB matrix is used to match expectations for DataSpace.
+ */
+Color bt2100YuvToRgb(Color e_gamma);
+
+/*
+ * Convert from scene luminance to HLG.
+ *
+ * [0.0, 1.0] range in and out.
+ */
+float hlgOetf(float e);
+Color hlgOetf(Color e);
+float hlgOetfLUT(float e);
+Color hlgOetfLUT(Color e);
+
+constexpr size_t kHlgOETFPrecision = 16;
+constexpr size_t kHlgOETFNumEntries = 1 << kHlgOETFPrecision;
+
+/*
+ * Convert from HLG to scene luminance.
+ *
+ * [0.0, 1.0] range in and out.
+ */
+float hlgInvOetf(float e_gamma);
+Color hlgInvOetf(Color e_gamma);
+float hlgInvOetfLUT(float e_gamma);
+Color hlgInvOetfLUT(Color e_gamma);
+
+constexpr size_t kHlgInvOETFPrecision = 12;
+constexpr size_t kHlgInvOETFNumEntries = 1 << kHlgInvOETFPrecision;
+
+/*
+ * Convert from scene luminance to PQ.
+ *
+ * [0.0, 1.0] range in and out.
+ */
+float pqOetf(float e);
+Color pqOetf(Color e);
+float pqOetfLUT(float e);
+Color pqOetfLUT(Color e);
+
+constexpr size_t kPqOETFPrecision = 16;
+constexpr size_t kPqOETFNumEntries = 1 << kPqOETFPrecision;
+
+/*
+ * Convert from PQ to scene luminance in nits.
+ *
+ * [0.0, 1.0] range in and out.
+ */
+float pqInvOetf(float e_gamma);
+Color pqInvOetf(Color e_gamma);
+float pqInvOetfLUT(float e_gamma);
+Color pqInvOetfLUT(Color e_gamma);
+
+constexpr size_t kPqInvOETFPrecision = 12;
+constexpr size_t kPqInvOETFNumEntries = 1 << kPqInvOETFPrecision;
+
+////////////////////////////////////////////////////////////////////////////////
+// Color space conversions
+
+/*
+ * Convert between color spaces with linear RGB data, according to ITU-R BT.2407 and EG 432-1.
+ *
+ * All conversions are derived from multiplying the matrix for XYZ to output RGB color gamut by the
+ * matrix for input RGB color gamut to XYZ. The matrix for converting from XYZ to an RGB gamut is
+ * always the inverse of the RGB gamut to XYZ matrix.
+ */
+Color bt709ToP3(Color e);
+Color bt709ToBt2100(Color e);
+Color p3ToBt709(Color e);
+Color p3ToBt2100(Color e);
+Color bt2100ToBt709(Color e);
+Color bt2100ToP3(Color e);
+
+/*
+ * Identity conversion.
+ */
+inline Color identityConversion(Color e) { return e; }
+
+/*
+ * Get the conversion to apply to the HDR image for gain map generation
+ */
+ColorTransformFn getHdrConversionFn(ultrahdr_color_gamut sdr_gamut, ultrahdr_color_gamut hdr_gamut);
+
+/*
+ * Convert between YUV encodings, according to ITU-R BT.709-6, ITU-R BT.601-7, and ITU-R BT.2100-2.
+ *
+ * Bt.709 and Bt.2100 have well-defined YUV encodings; Display-P3's is less well defined, but is
+ * treated as Bt.601 by DataSpace, hence we do the same.
+ */
+Color yuv709To601(Color e_gamma);
+Color yuv709To2100(Color e_gamma);
+Color yuv601To709(Color e_gamma);
+Color yuv601To2100(Color e_gamma);
+Color yuv2100To709(Color e_gamma);
+Color yuv2100To601(Color e_gamma);
+
+/*
+ * Performs a transformation at the chroma x and y coordinates provided on a YUV420 image.
+ *
+ * Apply the transformation by determining transformed YUV for each of the 4 Y + 1 UV; each Y gets
+ * this result, and UV gets the averaged result.
+ *
+ * x_chroma and y_chroma should be less than or equal to half the image's width and height
+ * respecitively, since input is 4:2:0 subsampled.
+ */
+void transformYuv420(jr_uncompressed_ptr image, size_t x_chroma, size_t y_chroma,
+ ColorTransformFn fn);
+
+////////////////////////////////////////////////////////////////////////////////
+// Gain map calculations
+
+/*
+ * Calculate the 8-bit unsigned integer gain value for the given SDR and HDR
+ * luminances in linear space, and the hdr ratio to encode against.
+ *
+ * Note: since this library always uses gamma of 1.0, offsetSdr of 0.0, and
+ * offsetHdr of 0.0, this function doesn't handle different metadata values for
+ * these fields.
+ */
+uint8_t encodeGain(float y_sdr, float y_hdr, ultrahdr_metadata_ptr metadata);
+uint8_t encodeGain(float y_sdr, float y_hdr, ultrahdr_metadata_ptr metadata,
+ float log2MinContentBoost, float log2MaxContentBoost);
+
+/*
+ * Calculates the linear luminance in nits after applying the given gain
+ * value, with the given hdr ratio, to the given sdr input in the range [0, 1].
+ *
+ * Note: similar to encodeGain(), this function only supports gamma 1.0,
+ * offsetSdr 0.0, offsetHdr 0.0, hdrCapacityMin 1.0, and hdrCapacityMax equal to
+ * gainMapMax, as this library encodes.
+ */
+Color applyGain(Color e, float gain, ultrahdr_metadata_ptr metadata);
+Color applyGain(Color e, float gain, ultrahdr_metadata_ptr metadata, float displayBoost);
+Color applyGainLUT(Color e, float gain, GainLUT& gainLUT);
+
+/*
+ * Helper for sampling from YUV 420 images.
+ */
+Color getYuv420Pixel(jr_uncompressed_ptr image, size_t x, size_t y);
+
+/*
+ * Helper for sampling from P010 images.
+ *
+ * Expect narrow-range image data for P010.
+ */
+Color getP010Pixel(jr_uncompressed_ptr image, size_t x, size_t y);
+
+/*
+ * Sample the image at the provided location, with a weighting based on nearby
+ * pixels and the map scale factor.
+ */
+Color sampleYuv420(jr_uncompressed_ptr map, size_t map_scale_factor, size_t x, size_t y);
+
+/*
+ * Sample the image at the provided location, with a weighting based on nearby
+ * pixels and the map scale factor.
+ *
+ * Expect narrow-range image data for P010.
+ */
+Color sampleP010(jr_uncompressed_ptr map, size_t map_scale_factor, size_t x, size_t y);
+
+/*
+ * Sample the gain value for the map from a given x,y coordinate on a scale
+ * that is map scale factor larger than the map size.
+ */
+float sampleMap(jr_uncompressed_ptr map, float map_scale_factor, size_t x, size_t y);
+float sampleMap(jr_uncompressed_ptr map, size_t map_scale_factor, size_t x, size_t y,
+ ShepardsIDW& weightTables);
+
+/*
+ * Convert from Color to RGBA1010102.
+ *
+ * Alpha always set to 1.0.
+ */
+uint32_t colorToRgba1010102(Color e_gamma);
+
+/*
+ * Convert from Color to F16.
+ *
+ * Alpha always set to 1.0.
+ */
+uint64_t colorToRgbaF16(Color e_gamma);
+
+} // namespace ultrahdr
+
+#endif // ULTRAHDR_GAINMAPMATH_H
generated by cgit v1.2.3 (git 2.25.1) at 2024-06-23 13:05:54 +0000