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// Copyright 2019 Joe Drago. All rights reserved.
// SPDX-License-Identifier: BSD-2-Clause
#include "avif/internal.h"
#include <assert.h>
#include <math.h>
#include <string.h>
struct YUVBlock
{
float y;
float u;
float v;
};
static avifBool avifPrepareReformatState(const avifImage * image, const avifRGBImage * rgb, avifReformatState * state)
{
if ((image->depth != 8) && (image->depth != 10) && (image->depth != 12)) {
return AVIF_FALSE;
}
if ((rgb->depth != 8) && (rgb->depth != 10) && (rgb->depth != 12) && (rgb->depth != 16)) {
return AVIF_FALSE;
}
if (rgb->isFloat && rgb->depth != 16) {
return AVIF_FALSE;
}
if (rgb->format == AVIF_RGB_FORMAT_RGB_565 && rgb->depth != 8) {
return AVIF_FALSE;
}
if (image->yuvFormat <= AVIF_PIXEL_FORMAT_NONE || image->yuvFormat >= AVIF_PIXEL_FORMAT_COUNT ||
rgb->format < AVIF_RGB_FORMAT_RGB || rgb->format >= AVIF_RGB_FORMAT_COUNT) {
return AVIF_FALSE;
}
if (image->yuvRange != AVIF_RANGE_LIMITED && image->yuvRange != AVIF_RANGE_FULL) {
return AVIF_FALSE;
}
// These matrix coefficients values are currently unsupported. Revise this list as more support is added.
//
// YCgCo performs limited-full range adjustment on R,G,B but the current implementation performs range adjustment
// on Y,U,V. So YCgCo with limited range is unsupported.
if ((image->matrixCoefficients == 3 /* CICP reserved */) ||
((image->matrixCoefficients == AVIF_MATRIX_COEFFICIENTS_YCGCO) && (image->yuvRange == AVIF_RANGE_LIMITED)) ||
(image->matrixCoefficients == AVIF_MATRIX_COEFFICIENTS_BT2020_CL) ||
(image->matrixCoefficients == AVIF_MATRIX_COEFFICIENTS_SMPTE2085) ||
(image->matrixCoefficients == AVIF_MATRIX_COEFFICIENTS_CHROMA_DERIVED_CL) ||
(image->matrixCoefficients >= AVIF_MATRIX_COEFFICIENTS_ICTCP)) { // Note the >= catching "future" CICP values here too
return AVIF_FALSE;
}
if ((image->matrixCoefficients == AVIF_MATRIX_COEFFICIENTS_IDENTITY) && (image->yuvFormat != AVIF_PIXEL_FORMAT_YUV444)) {
return AVIF_FALSE;
}
avifGetPixelFormatInfo(image->yuvFormat, &state->formatInfo);
avifCalcYUVCoefficients(image, &state->kr, &state->kg, &state->kb);
state->mode = AVIF_REFORMAT_MODE_YUV_COEFFICIENTS;
if (image->matrixCoefficients == AVIF_MATRIX_COEFFICIENTS_IDENTITY) {
state->mode = AVIF_REFORMAT_MODE_IDENTITY;
} else if (image->matrixCoefficients == AVIF_MATRIX_COEFFICIENTS_YCGCO) {
state->mode = AVIF_REFORMAT_MODE_YCGCO;
}
if (state->mode != AVIF_REFORMAT_MODE_YUV_COEFFICIENTS) {
state->kr = 0.0f;
state->kg = 0.0f;
state->kb = 0.0f;
}
state->yuvChannelBytes = (image->depth > 8) ? 2 : 1;
state->rgbChannelBytes = (rgb->depth > 8) ? 2 : 1;
state->rgbChannelCount = avifRGBFormatChannelCount(rgb->format);
state->rgbPixelBytes = avifRGBImagePixelSize(rgb);
switch (rgb->format) {
case AVIF_RGB_FORMAT_RGB:
state->rgbOffsetBytesR = state->rgbChannelBytes * 0;
state->rgbOffsetBytesG = state->rgbChannelBytes * 1;
state->rgbOffsetBytesB = state->rgbChannelBytes * 2;
state->rgbOffsetBytesA = 0;
break;
case AVIF_RGB_FORMAT_RGBA:
state->rgbOffsetBytesR = state->rgbChannelBytes * 0;
state->rgbOffsetBytesG = state->rgbChannelBytes * 1;
state->rgbOffsetBytesB = state->rgbChannelBytes * 2;
state->rgbOffsetBytesA = state->rgbChannelBytes * 3;
break;
case AVIF_RGB_FORMAT_ARGB:
state->rgbOffsetBytesA = state->rgbChannelBytes * 0;
state->rgbOffsetBytesR = state->rgbChannelBytes * 1;
state->rgbOffsetBytesG = state->rgbChannelBytes * 2;
state->rgbOffsetBytesB = state->rgbChannelBytes * 3;
break;
case AVIF_RGB_FORMAT_BGR:
state->rgbOffsetBytesB = state->rgbChannelBytes * 0;
state->rgbOffsetBytesG = state->rgbChannelBytes * 1;
state->rgbOffsetBytesR = state->rgbChannelBytes * 2;
state->rgbOffsetBytesA = 0;
break;
case AVIF_RGB_FORMAT_BGRA:
state->rgbOffsetBytesB = state->rgbChannelBytes * 0;
state->rgbOffsetBytesG = state->rgbChannelBytes * 1;
state->rgbOffsetBytesR = state->rgbChannelBytes * 2;
state->rgbOffsetBytesA = state->rgbChannelBytes * 3;
break;
case AVIF_RGB_FORMAT_ABGR:
state->rgbOffsetBytesA = state->rgbChannelBytes * 0;
state->rgbOffsetBytesB = state->rgbChannelBytes * 1;
state->rgbOffsetBytesG = state->rgbChannelBytes * 2;
state->rgbOffsetBytesR = state->rgbChannelBytes * 3;
break;
case AVIF_RGB_FORMAT_RGB_565:
// Since RGB_565 consists of two bytes per RGB pixel, we simply use
// the pointer to the red channel to populate the entire pixel value
// as a uint16_t. As a result only rgbOffsetBytesR is used and the
// other offsets are unused.
state->rgbOffsetBytesR = 0;
state->rgbOffsetBytesG = 0;
state->rgbOffsetBytesB = 0;
state->rgbOffsetBytesA = 0;
break;
case AVIF_RGB_FORMAT_COUNT:
return AVIF_FALSE;
}
state->yuvDepth = image->depth;
state->yuvRange = image->yuvRange;
state->yuvMaxChannel = (1 << image->depth) - 1;
state->rgbMaxChannel = (1 << rgb->depth) - 1;
state->rgbMaxChannelF = (float)state->rgbMaxChannel;
state->biasY = (state->yuvRange == AVIF_RANGE_LIMITED) ? (float)(16 << (state->yuvDepth - 8)) : 0.0f;
state->biasUV = (float)(1 << (state->yuvDepth - 1));
state->rangeY = (float)((state->yuvRange == AVIF_RANGE_LIMITED) ? (219 << (state->yuvDepth - 8)) : state->yuvMaxChannel);
state->rangeUV = (float)((state->yuvRange == AVIF_RANGE_LIMITED) ? (224 << (state->yuvDepth - 8)) : state->yuvMaxChannel);
uint32_t cpCount = 1 << image->depth;
if (state->mode == AVIF_REFORMAT_MODE_IDENTITY) {
for (uint32_t cp = 0; cp < cpCount; ++cp) {
state->unormFloatTableY[cp] = ((float)cp - state->biasY) / state->rangeY;
state->unormFloatTableUV[cp] = ((float)cp - state->biasY) / state->rangeY;
}
} else {
for (uint32_t cp = 0; cp < cpCount; ++cp) {
// Review this when implementing YCgCo limited range support.
state->unormFloatTableY[cp] = ((float)cp - state->biasY) / state->rangeY;
state->unormFloatTableUV[cp] = ((float)cp - state->biasUV) / state->rangeUV;
}
}
state->toRGBAlphaMode = AVIF_ALPHA_MULTIPLY_MODE_NO_OP;
if (image->alphaPlane) {
if (!avifRGBFormatHasAlpha(rgb->format) || rgb->ignoreAlpha) {
// if we are converting some image with alpha into a format without alpha, we should do 'premultiply alpha' before
// discarding alpha plane. This has the same effect of rendering this image on a black background, which makes sense.
if (!image->alphaPremultiplied) {
state->toRGBAlphaMode = AVIF_ALPHA_MULTIPLY_MODE_MULTIPLY;
}
} else {
if (!image->alphaPremultiplied && rgb->alphaPremultiplied) {
state->toRGBAlphaMode = AVIF_ALPHA_MULTIPLY_MODE_MULTIPLY;
} else if (image->alphaPremultiplied && !rgb->alphaPremultiplied) {
state->toRGBAlphaMode = AVIF_ALPHA_MULTIPLY_MODE_UNMULTIPLY;
}
}
}
return AVIF_TRUE;
}
// Formulas 20-31 from https://www.itu.int/rec/T-REC-H.273-201612-I/en
static int avifReformatStateYToUNorm(avifReformatState * state, float v)
{
int unorm = (int)avifRoundf(v * state->rangeY + state->biasY);
return AVIF_CLAMP(unorm, 0, state->yuvMaxChannel);
}
static int avifReformatStateUVToUNorm(avifReformatState * state, float v)
{
int unorm;
// YCgCo performs limited-full range adjustment on R,G,B but the current implementation performs range adjustment
// on Y,U,V. So YCgCo with limited range is unsupported.
assert((state->mode != AVIF_REFORMAT_MODE_YCGCO) || (state->yuvRange == AVIF_RANGE_FULL));
if (state->mode == AVIF_REFORMAT_MODE_IDENTITY) {
unorm = (int)avifRoundf(v * state->rangeY + state->biasY);
} else {
unorm = (int)avifRoundf(v * state->rangeUV + state->biasUV);
}
return AVIF_CLAMP(unorm, 0, state->yuvMaxChannel);
}
avifResult avifImageRGBToYUV(avifImage * image, const avifRGBImage * rgb)
{
if (!rgb->pixels || rgb->format == AVIF_RGB_FORMAT_RGB_565) {
return AVIF_RESULT_REFORMAT_FAILED;
}
avifReformatState state;
if (!avifPrepareReformatState(image, rgb, &state)) {
return AVIF_RESULT_REFORMAT_FAILED;
}
if (rgb->isFloat) {
return AVIF_RESULT_NOT_IMPLEMENTED;
}
const avifBool hasAlpha = avifRGBFormatHasAlpha(rgb->format) && !rgb->ignoreAlpha;
avifResult allocationResult = avifImageAllocatePlanes(image, hasAlpha ? AVIF_PLANES_ALL : AVIF_PLANES_YUV);
if (allocationResult != AVIF_RESULT_OK) {
return allocationResult;
}
avifAlphaMultiplyMode alphaMode = AVIF_ALPHA_MULTIPLY_MODE_NO_OP;
if (hasAlpha) {
if (!rgb->alphaPremultiplied && image->alphaPremultiplied) {
alphaMode = AVIF_ALPHA_MULTIPLY_MODE_MULTIPLY;
} else if (rgb->alphaPremultiplied && !image->alphaPremultiplied) {
alphaMode = AVIF_ALPHA_MULTIPLY_MODE_UNMULTIPLY;
}
}
avifBool converted = AVIF_FALSE;
// Try converting with libsharpyuv.
if ((rgb->chromaDownsampling == AVIF_CHROMA_DOWNSAMPLING_SHARP_YUV) && (image->yuvFormat == AVIF_PIXEL_FORMAT_YUV420)) {
const avifResult libSharpYUVResult = avifImageRGBToYUVLibSharpYUV(image, rgb, &state);
if (libSharpYUVResult != AVIF_RESULT_OK) {
// Return the error if sharpyuv was requested but failed for any reason, including libsharpyuv not being available.
return libSharpYUVResult;
}
converted = AVIF_TRUE;
}
if (!converted && !rgb->avoidLibYUV && (alphaMode == AVIF_ALPHA_MULTIPLY_MODE_NO_OP)) {
avifResult libyuvResult = avifImageRGBToYUVLibYUV(image, rgb);
if (libyuvResult == AVIF_RESULT_OK) {
converted = AVIF_TRUE;
} else if (libyuvResult != AVIF_RESULT_NOT_IMPLEMENTED) {
return libyuvResult;
}
}
if (!converted) {
const float kr = state.kr;
const float kg = state.kg;
const float kb = state.kb;
struct YUVBlock yuvBlock[2][2];
float rgbPixel[3];
const float rgbMaxChannelF = state.rgbMaxChannelF;
uint8_t ** yuvPlanes = image->yuvPlanes;
uint32_t * yuvRowBytes = image->yuvRowBytes;
for (uint32_t outerJ = 0; outerJ < image->height; outerJ += 2) {
for (uint32_t outerI = 0; outerI < image->width; outerI += 2) {
int blockW = 2, blockH = 2;
if ((outerI + 1) >= image->width) {
blockW = 1;
}
if ((outerJ + 1) >= image->height) {
blockH = 1;
}
// Convert an entire 2x2 block to YUV, and populate any fully sampled channels as we go
for (int bJ = 0; bJ < blockH; ++bJ) {
for (int bI = 0; bI < blockW; ++bI) {
int i = outerI + bI;
int j = outerJ + bJ;
// Unpack RGB into normalized float
if (state.rgbChannelBytes > 1) {
rgbPixel[0] =
*((uint16_t *)(&rgb->pixels[state.rgbOffsetBytesR + (i * state.rgbPixelBytes) + (j * rgb->rowBytes)])) /
rgbMaxChannelF;
rgbPixel[1] =
*((uint16_t *)(&rgb->pixels[state.rgbOffsetBytesG + (i * state.rgbPixelBytes) + (j * rgb->rowBytes)])) /
rgbMaxChannelF;
rgbPixel[2] =
*((uint16_t *)(&rgb->pixels[state.rgbOffsetBytesB + (i * state.rgbPixelBytes) + (j * rgb->rowBytes)])) /
rgbMaxChannelF;
} else {
rgbPixel[0] = rgb->pixels[state.rgbOffsetBytesR + (i * state.rgbPixelBytes) + (j * rgb->rowBytes)] /
rgbMaxChannelF;
rgbPixel[1] = rgb->pixels[state.rgbOffsetBytesG + (i * state.rgbPixelBytes) + (j * rgb->rowBytes)] /
rgbMaxChannelF;
rgbPixel[2] = rgb->pixels[state.rgbOffsetBytesB + (i * state.rgbPixelBytes) + (j * rgb->rowBytes)] /
rgbMaxChannelF;
}
if (alphaMode != AVIF_ALPHA_MULTIPLY_MODE_NO_OP) {
float a;
if (state.rgbChannelBytes > 1) {
a = *((uint16_t *)(&rgb->pixels[state.rgbOffsetBytesA + (i * state.rgbPixelBytes) + (j * rgb->rowBytes)])) /
rgbMaxChannelF;
} else {
a = rgb->pixels[state.rgbOffsetBytesA + (i * state.rgbPixelBytes) + (j * rgb->rowBytes)] / rgbMaxChannelF;
}
if (alphaMode == AVIF_ALPHA_MULTIPLY_MODE_MULTIPLY) {
if (a == 0) {
rgbPixel[0] = 0;
rgbPixel[1] = 0;
rgbPixel[2] = 0;
} else if (a < 1.0f) {
rgbPixel[0] *= a;
rgbPixel[1] *= a;
rgbPixel[2] *= a;
}
} else {
// alphaMode == AVIF_ALPHA_MULTIPLY_MODE_UNMULTIPLY
if (a == 0) {
rgbPixel[0] = 0;
rgbPixel[1] = 0;
rgbPixel[2] = 0;
} else if (a < 1.0f) {
rgbPixel[0] /= a;
rgbPixel[1] /= a;
rgbPixel[2] /= a;
rgbPixel[0] = AVIF_MIN(rgbPixel[0], 1.0f);
rgbPixel[1] = AVIF_MIN(rgbPixel[1], 1.0f);
rgbPixel[2] = AVIF_MIN(rgbPixel[2], 1.0f);
}
}
}
// RGB -> YUV conversion
if (state.mode == AVIF_REFORMAT_MODE_IDENTITY) {
// Formulas 41,42,43 from https://www.itu.int/rec/T-REC-H.273-201612-I/en
yuvBlock[bI][bJ].y = rgbPixel[1]; // G
yuvBlock[bI][bJ].u = rgbPixel[2]; // B
yuvBlock[bI][bJ].v = rgbPixel[0]; // R
} else if (state.mode == AVIF_REFORMAT_MODE_YCGCO) {
// Formulas 44,45,46 from https://www.itu.int/rec/T-REC-H.273-201612-I/en
yuvBlock[bI][bJ].y = 0.5f * rgbPixel[1] + 0.25f * (rgbPixel[0] + rgbPixel[2]);
yuvBlock[bI][bJ].u = 0.5f * rgbPixel[1] - 0.25f * (rgbPixel[0] + rgbPixel[2]);
yuvBlock[bI][bJ].v = 0.5f * (rgbPixel[0] - rgbPixel[2]);
} else {
float Y = (kr * rgbPixel[0]) + (kg * rgbPixel[1]) + (kb * rgbPixel[2]);
yuvBlock[bI][bJ].y = Y;
yuvBlock[bI][bJ].u = (rgbPixel[2] - Y) / (2 * (1 - kb));
yuvBlock[bI][bJ].v = (rgbPixel[0] - Y) / (2 * (1 - kr));
}
if (state.yuvChannelBytes > 1) {
uint16_t * pY = (uint16_t *)&yuvPlanes[AVIF_CHAN_Y][(i * 2) + (j * yuvRowBytes[AVIF_CHAN_Y])];
*pY = (uint16_t)avifReformatStateYToUNorm(&state, yuvBlock[bI][bJ].y);
if (image->yuvFormat == AVIF_PIXEL_FORMAT_YUV444) {
// YUV444, full chroma
uint16_t * pU = (uint16_t *)&yuvPlanes[AVIF_CHAN_U][(i * 2) + (j * yuvRowBytes[AVIF_CHAN_U])];
*pU = (uint16_t)avifReformatStateUVToUNorm(&state, yuvBlock[bI][bJ].u);
uint16_t * pV = (uint16_t *)&yuvPlanes[AVIF_CHAN_V][(i * 2) + (j * yuvRowBytes[AVIF_CHAN_V])];
*pV = (uint16_t)avifReformatStateUVToUNorm(&state, yuvBlock[bI][bJ].v);
}
} else {
yuvPlanes[AVIF_CHAN_Y][i + (j * yuvRowBytes[AVIF_CHAN_Y])] =
(uint8_t)avifReformatStateYToUNorm(&state, yuvBlock[bI][bJ].y);
if (image->yuvFormat == AVIF_PIXEL_FORMAT_YUV444) {
// YUV444, full chroma
yuvPlanes[AVIF_CHAN_U][i + (j * yuvRowBytes[AVIF_CHAN_U])] =
(uint8_t)avifReformatStateUVToUNorm(&state, yuvBlock[bI][bJ].u);
yuvPlanes[AVIF_CHAN_V][i + (j * yuvRowBytes[AVIF_CHAN_V])] =
(uint8_t)avifReformatStateUVToUNorm(&state, yuvBlock[bI][bJ].v);
}
}
}
}
// Populate any subsampled channels with averages from the 2x2 block
if (image->yuvFormat == AVIF_PIXEL_FORMAT_YUV420) {
// YUV420, average 4 samples (2x2)
float sumU = 0.0f;
float sumV = 0.0f;
for (int bJ = 0; bJ < blockH; ++bJ) {
for (int bI = 0; bI < blockW; ++bI) {
sumU += yuvBlock[bI][bJ].u;
sumV += yuvBlock[bI][bJ].v;
}
}
float totalSamples = (float)(blockW * blockH);
float avgU = sumU / totalSamples;
float avgV = sumV / totalSamples;
const int chromaShiftX = 1;
const int chromaShiftY = 1;
int uvI = outerI >> chromaShiftX;
int uvJ = outerJ >> chromaShiftY;
if (state.yuvChannelBytes > 1) {
uint16_t * pU = (uint16_t *)&yuvPlanes[AVIF_CHAN_U][(uvI * 2) + (uvJ * yuvRowBytes[AVIF_CHAN_U])];
*pU = (uint16_t)avifReformatStateUVToUNorm(&state, avgU);
uint16_t * pV = (uint16_t *)&yuvPlanes[AVIF_CHAN_V][(uvI * 2) + (uvJ * yuvRowBytes[AVIF_CHAN_V])];
*pV = (uint16_t)avifReformatStateUVToUNorm(&state, avgV);
} else {
yuvPlanes[AVIF_CHAN_U][uvI + (uvJ * yuvRowBytes[AVIF_CHAN_U])] =
(uint8_t)avifReformatStateUVToUNorm(&state, avgU);
yuvPlanes[AVIF_CHAN_V][uvI + (uvJ * yuvRowBytes[AVIF_CHAN_V])] =
(uint8_t)avifReformatStateUVToUNorm(&state, avgV);
}
} else if (image->yuvFormat == AVIF_PIXEL_FORMAT_YUV422) {
// YUV422, average 2 samples (1x2), twice
for (int bJ = 0; bJ < blockH; ++bJ) {
float sumU = 0.0f;
float sumV = 0.0f;
for (int bI = 0; bI < blockW; ++bI) {
sumU += yuvBlock[bI][bJ].u;
sumV += yuvBlock[bI][bJ].v;
}
float totalSamples = (float)blockW;
float avgU = sumU / totalSamples;
float avgV = sumV / totalSamples;
const int chromaShiftX = 1;
int uvI = outerI >> chromaShiftX;
int uvJ = outerJ + bJ;
if (state.yuvChannelBytes > 1) {
uint16_t * pU = (uint16_t *)&yuvPlanes[AVIF_CHAN_U][(uvI * 2) + (uvJ * yuvRowBytes[AVIF_CHAN_U])];
*pU = (uint16_t)avifReformatStateUVToUNorm(&state, avgU);
uint16_t * pV = (uint16_t *)&yuvPlanes[AVIF_CHAN_V][(uvI * 2) + (uvJ * yuvRowBytes[AVIF_CHAN_V])];
*pV = (uint16_t)avifReformatStateUVToUNorm(&state, avgV);
} else {
yuvPlanes[AVIF_CHAN_U][uvI + (uvJ * yuvRowBytes[AVIF_CHAN_U])] =
(uint8_t)avifReformatStateUVToUNorm(&state, avgU);
yuvPlanes[AVIF_CHAN_V][uvI + (uvJ * yuvRowBytes[AVIF_CHAN_V])] =
(uint8_t)avifReformatStateUVToUNorm(&state, avgV);
}
}
}
}
}
}
if (image->alphaPlane && image->alphaRowBytes) {
avifAlphaParams params;
params.width = image->width;
params.height = image->height;
params.dstDepth = image->depth;
params.dstPlane = image->alphaPlane;
params.dstRowBytes = image->alphaRowBytes;
params.dstOffsetBytes = 0;
params.dstPixelBytes = state.yuvChannelBytes;
if (avifRGBFormatHasAlpha(rgb->format) && !rgb->ignoreAlpha) {
params.srcDepth = rgb->depth;
params.srcPlane = rgb->pixels;
params.srcRowBytes = rgb->rowBytes;
params.srcOffsetBytes = state.rgbOffsetBytesA;
params.srcPixelBytes = state.rgbPixelBytes;
avifReformatAlpha(¶ms);
} else {
// libyuv does not fill alpha when converting from RGB to YUV so
// fill it regardless of the value of convertedWithLibYUV.
avifFillAlpha(¶ms);
}
}
return AVIF_RESULT_OK;
}
#define RGB565(R, G, B) ((uint16_t)(((B) >> 3) | (((G) >> 2) << 5) | (((R) >> 3) << 11)))
static void avifStoreRGB8Pixel(avifRGBFormat format, uint8_t R, uint8_t G, uint8_t B, uint8_t * ptrR, uint8_t * ptrG, uint8_t * ptrB)
{
if (format == AVIF_RGB_FORMAT_RGB_565) {
// References for RGB565 color conversion:
// * https://docs.microsoft.com/en-us/windows/win32/directshow/working-with-16-bit-rgb
// * https://chromium.googlesource.com/libyuv/libyuv/+/9892d70c965678381d2a70a1c9002d1cf136ee78/source/row_common.cc#2362
*(uint16_t *)ptrR = RGB565(R, G, B);
return;
}
*ptrR = R;
*ptrG = G;
*ptrB = B;
}
// Note: This function handles alpha (un)multiply.
static avifResult avifImageYUVAnyToRGBAnySlow(const avifImage * image, avifRGBImage * rgb, avifReformatState * state)
{
// Aliases for some state
const float kr = state->kr;
const float kg = state->kg;
const float kb = state->kb;
const float * const unormFloatTableY = state->unormFloatTableY;
const float * const unormFloatTableUV = state->unormFloatTableUV;
const uint32_t yuvChannelBytes = state->yuvChannelBytes;
const uint32_t rgbPixelBytes = state->rgbPixelBytes;
// Aliases for plane data
const uint8_t * yPlane = image->yuvPlanes[AVIF_CHAN_Y];
const uint8_t * uPlane = image->yuvPlanes[AVIF_CHAN_U];
const uint8_t * vPlane = image->yuvPlanes[AVIF_CHAN_V];
const uint8_t * aPlane = image->alphaPlane;
const uint32_t yRowBytes = image->yuvRowBytes[AVIF_CHAN_Y];
const uint32_t uRowBytes = image->yuvRowBytes[AVIF_CHAN_U];
const uint32_t vRowBytes = image->yuvRowBytes[AVIF_CHAN_V];
const uint32_t aRowBytes = image->alphaRowBytes;
// Various observations and limits
const avifBool hasColor = (uPlane && vPlane && (image->yuvFormat != AVIF_PIXEL_FORMAT_YUV400));
const uint16_t yuvMaxChannel = (uint16_t)state->yuvMaxChannel;
const float rgbMaxChannelF = state->rgbMaxChannelF;
// If toRGBAlphaMode is active (not no-op), assert that the alpha plane is present. The end of
// the avifPrepareReformatState() function should ensure this, but this assert makes it clear
// to clang's analyzer.
assert((state->toRGBAlphaMode == AVIF_ALPHA_MULTIPLY_MODE_NO_OP) || aPlane);
for (uint32_t j = 0; j < image->height; ++j) {
const uint32_t uvJ = j >> state->formatInfo.chromaShiftY;
const uint8_t * ptrY8 = &yPlane[j * yRowBytes];
const uint8_t * ptrU8 = uPlane ? &uPlane[(uvJ * uRowBytes)] : NULL;
const uint8_t * ptrV8 = vPlane ? &vPlane[(uvJ * vRowBytes)] : NULL;
const uint8_t * ptrA8 = aPlane ? &aPlane[j * aRowBytes] : NULL;
const uint16_t * ptrY16 = (const uint16_t *)ptrY8;
const uint16_t * ptrU16 = (const uint16_t *)ptrU8;
const uint16_t * ptrV16 = (const uint16_t *)ptrV8;
const uint16_t * ptrA16 = (const uint16_t *)ptrA8;
uint8_t * ptrR = &rgb->pixels[state->rgbOffsetBytesR + (j * rgb->rowBytes)];
uint8_t * ptrG = &rgb->pixels[state->rgbOffsetBytesG + (j * rgb->rowBytes)];
uint8_t * ptrB = &rgb->pixels[state->rgbOffsetBytesB + (j * rgb->rowBytes)];
for (uint32_t i = 0; i < image->width; ++i) {
uint32_t uvI = i >> state->formatInfo.chromaShiftX;
float Y, Cb = 0.5f, Cr = 0.5f;
// Calculate Y
uint16_t unormY;
if (image->depth == 8) {
unormY = ptrY8[i];
} else {
// clamp incoming data to protect against bad LUT lookups
unormY = AVIF_MIN(ptrY16[i], yuvMaxChannel);
}
Y = unormFloatTableY[unormY];
// Calculate Cb and Cr
if (hasColor) {
if (image->yuvFormat == AVIF_PIXEL_FORMAT_YUV444) {
uint16_t unormU, unormV;
if (image->depth == 8) {
unormU = ptrU8[uvI];
unormV = ptrV8[uvI];
} else {
// clamp incoming data to protect against bad LUT lookups
unormU = AVIF_MIN(ptrU16[uvI], yuvMaxChannel);
unormV = AVIF_MIN(ptrV16[uvI], yuvMaxChannel);
}
Cb = unormFloatTableUV[unormU];
Cr = unormFloatTableUV[unormV];
} else {
// Upsample to 444:
//
// * * * *
// A B
// * 1 2 *
//
// * 3 4 *
// C D
// * * * *
//
// When converting from YUV420 to RGB, for any given "high-resolution" RGB
// coordinate (1,2,3,4,*), there are up to four "low-resolution" UV samples
// (A,B,C,D) that are "nearest" to the pixel. For RGB pixel #1, A is the closest
// UV sample, B and C are "adjacent" to it on the same row and column, and D is
// the diagonal. For RGB pixel 3, C is the closest UV sample, A and D are
// adjacent, and B is the diagonal. Sometimes the adjacent pixel on the same row
// is to the left or right, and sometimes the adjacent pixel on the same column
// is up or down. For any edge or corner, there might only be only one or two
// samples nearby, so they'll be duplicated.
//
// The following code attempts to find all four nearest UV samples and put them
// in the following unormU and unormV grid as follows:
//
// unorm[0][0] = closest ( weights: bilinear: 9/16, nearest: 1 )
// unorm[1][0] = adjacent col ( weights: bilinear: 3/16, nearest: 0 )
// unorm[0][1] = adjacent row ( weights: bilinear: 3/16, nearest: 0 )
// unorm[1][1] = diagonal ( weights: bilinear: 1/16, nearest: 0 )
//
// It then weights them according to the requested upsampling set in avifRGBImage.
uint16_t unormU[2][2], unormV[2][2];
// How many bytes to add to a uint8_t pointer index to get to the adjacent (lesser) sample in a given direction
int uAdjCol, vAdjCol, uAdjRow, vAdjRow;
if ((i == 0) || ((i == (image->width - 1)) && ((i % 2) != 0))) {
uAdjCol = 0;
vAdjCol = 0;
} else {
if ((i % 2) != 0) {
uAdjCol = yuvChannelBytes;
vAdjCol = yuvChannelBytes;
} else {
uAdjCol = -1 * yuvChannelBytes;
vAdjCol = -1 * yuvChannelBytes;
}
}
// For YUV422, uvJ will always be a fresh value (always corresponds to j), so
// we'll simply duplicate the sample as if we were on the top or bottom row and
// it'll behave as plain old linear (1D) upsampling, which is all we want.
if ((j == 0) || ((j == (image->height - 1)) && ((j % 2) != 0)) || (image->yuvFormat == AVIF_PIXEL_FORMAT_YUV422)) {
uAdjRow = 0;
vAdjRow = 0;
} else {
if ((j % 2) != 0) {
uAdjRow = (int)uRowBytes;
vAdjRow = (int)vRowBytes;
} else {
uAdjRow = -1 * (int)uRowBytes;
vAdjRow = -1 * (int)vRowBytes;
}
}
if (image->depth == 8) {
unormU[0][0] = uPlane[(uvJ * uRowBytes) + (uvI * yuvChannelBytes)];
unormV[0][0] = vPlane[(uvJ * vRowBytes) + (uvI * yuvChannelBytes)];
unormU[1][0] = uPlane[(uvJ * uRowBytes) + (uvI * yuvChannelBytes) + uAdjCol];
unormV[1][0] = vPlane[(uvJ * vRowBytes) + (uvI * yuvChannelBytes) + vAdjCol];
unormU[0][1] = uPlane[(uvJ * uRowBytes) + (uvI * yuvChannelBytes) + uAdjRow];
unormV[0][1] = vPlane[(uvJ * vRowBytes) + (uvI * yuvChannelBytes) + vAdjRow];
unormU[1][1] = uPlane[(uvJ * uRowBytes) + (uvI * yuvChannelBytes) + uAdjCol + uAdjRow];
unormV[1][1] = vPlane[(uvJ * vRowBytes) + (uvI * yuvChannelBytes) + vAdjCol + vAdjRow];
} else {
unormU[0][0] = *((const uint16_t *)&uPlane[(uvJ * uRowBytes) + (uvI * yuvChannelBytes)]);
unormV[0][0] = *((const uint16_t *)&vPlane[(uvJ * vRowBytes) + (uvI * yuvChannelBytes)]);
unormU[1][0] = *((const uint16_t *)&uPlane[(uvJ * uRowBytes) + (uvI * yuvChannelBytes) + uAdjCol]);
unormV[1][0] = *((const uint16_t *)&vPlane[(uvJ * vRowBytes) + (uvI * yuvChannelBytes) + vAdjCol]);
unormU[0][1] = *((const uint16_t *)&uPlane[(uvJ * uRowBytes) + (uvI * yuvChannelBytes) + uAdjRow]);
unormV[0][1] = *((const uint16_t *)&vPlane[(uvJ * vRowBytes) + (uvI * yuvChannelBytes) + vAdjRow]);
unormU[1][1] = *((const uint16_t *)&uPlane[(uvJ * uRowBytes) + (uvI * yuvChannelBytes) + uAdjCol + uAdjRow]);
unormV[1][1] = *((const uint16_t *)&vPlane[(uvJ * vRowBytes) + (uvI * yuvChannelBytes) + vAdjCol + vAdjRow]);
// clamp incoming data to protect against bad LUT lookups
for (int bJ = 0; bJ < 2; ++bJ) {
for (int bI = 0; bI < 2; ++bI) {
unormU[bI][bJ] = AVIF_MIN(unormU[bI][bJ], yuvMaxChannel);
unormV[bI][bJ] = AVIF_MIN(unormV[bI][bJ], yuvMaxChannel);
}
}
}
if ((rgb->chromaUpsampling == AVIF_CHROMA_UPSAMPLING_FASTEST) ||
(rgb->chromaUpsampling == AVIF_CHROMA_UPSAMPLING_NEAREST)) {
// Nearest neighbor; ignore all UVs but the closest one
Cb = unormFloatTableUV[unormU[0][0]];
Cr = unormFloatTableUV[unormV[0][0]];
} else {
// Bilinear filtering with weights
Cb = (unormFloatTableUV[unormU[0][0]] * (9.0f / 16.0f)) + (unormFloatTableUV[unormU[1][0]] * (3.0f / 16.0f)) +
(unormFloatTableUV[unormU[0][1]] * (3.0f / 16.0f)) + (unormFloatTableUV[unormU[1][1]] * (1.0f / 16.0f));
Cr = (unormFloatTableUV[unormV[0][0]] * (9.0f / 16.0f)) + (unormFloatTableUV[unormV[1][0]] * (3.0f / 16.0f)) +
(unormFloatTableUV[unormV[0][1]] * (3.0f / 16.0f)) + (unormFloatTableUV[unormV[1][1]] * (1.0f / 16.0f));
}
}
}
float R, G, B;
if (hasColor) {
if (state->mode == AVIF_REFORMAT_MODE_IDENTITY) {
// Identity (GBR): Formulas 41,42,43 from https://www.itu.int/rec/T-REC-H.273-201612-I/en
G = Y;
B = Cb;
R = Cr;
} else if (state->mode == AVIF_REFORMAT_MODE_YCGCO) {
// YCgCo: Formulas 47,48,49,50 from https://www.itu.int/rec/T-REC-H.273-201612-I/en
const float t = Y - Cb;
G = Y + Cb;
B = t - Cr;
R = t + Cr;
} else {
// Normal YUV
R = Y + (2 * (1 - kr)) * Cr;
B = Y + (2 * (1 - kb)) * Cb;
G = Y - ((2 * ((kr * (1 - kr) * Cr) + (kb * (1 - kb) * Cb))) / kg);
}
} else {
// Monochrome: just populate all channels with luma (identity mode is irrelevant)
R = Y;
G = Y;
B = Y;
}
float Rc = AVIF_CLAMP(R, 0.0f, 1.0f);
float Gc = AVIF_CLAMP(G, 0.0f, 1.0f);
float Bc = AVIF_CLAMP(B, 0.0f, 1.0f);
if (state->toRGBAlphaMode != AVIF_ALPHA_MULTIPLY_MODE_NO_OP) {
// Calculate A
uint16_t unormA;
if (image->depth == 8) {
unormA = ptrA8[i];
} else {
unormA = AVIF_MIN(ptrA16[i], yuvMaxChannel);
}
const float A = unormA / ((float)state->yuvMaxChannel);
const float Ac = AVIF_CLAMP(A, 0.0f, 1.0f);
if (state->toRGBAlphaMode == AVIF_ALPHA_MULTIPLY_MODE_MULTIPLY) {
if (Ac == 0.0f) {
Rc = 0.0f;
Gc = 0.0f;
Bc = 0.0f;
} else if (Ac < 1.0f) {
Rc *= Ac;
Gc *= Ac;
Bc *= Ac;
}
} else {
// state->toRGBAlphaMode == AVIF_ALPHA_MULTIPLY_MODE_UNMULTIPLY
if (Ac == 0.0f) {
Rc = 0.0f;
Gc = 0.0f;
Bc = 0.0f;
} else if (Ac < 1.0f) {
Rc /= Ac;
Gc /= Ac;
Bc /= Ac;
Rc = AVIF_MIN(Rc, 1.0f);
Gc = AVIF_MIN(Gc, 1.0f);
Bc = AVIF_MIN(Bc, 1.0f);
}
}
}
if (rgb->depth == 8) {
avifStoreRGB8Pixel(rgb->format,
(uint8_t)(0.5f + (Rc * rgbMaxChannelF)),
(uint8_t)(0.5f + (Gc * rgbMaxChannelF)),
(uint8_t)(0.5f + (Bc * rgbMaxChannelF)),
ptrR,
ptrG,
ptrB);
} else {
*((uint16_t *)ptrR) = (uint16_t)(0.5f + (Rc * rgbMaxChannelF));
*((uint16_t *)ptrG) = (uint16_t)(0.5f + (Gc * rgbMaxChannelF));
*((uint16_t *)ptrB) = (uint16_t)(0.5f + (Bc * rgbMaxChannelF));
}
ptrR += rgbPixelBytes;
ptrG += rgbPixelBytes;
ptrB += rgbPixelBytes;
}
}
return AVIF_RESULT_OK;
}
static avifResult avifImageYUV16ToRGB16Color(const avifImage * image, avifRGBImage * rgb, avifReformatState * state)
{
const float kr = state->kr;
const float kg = state->kg;
const float kb = state->kb;
const uint32_t rgbPixelBytes = state->rgbPixelBytes;
const float * const unormFloatTableY = state->unormFloatTableY;
const float * const unormFloatTableUV = state->unormFloatTableUV;
const uint16_t yuvMaxChannel = (uint16_t)state->yuvMaxChannel;
const float rgbMaxChannelF = state->rgbMaxChannelF;
for (uint32_t j = 0; j < image->height; ++j) {
const uint32_t uvJ = j >> state->formatInfo.chromaShiftY;
const uint16_t * const ptrY = (uint16_t *)&image->yuvPlanes[AVIF_CHAN_Y][(j * image->yuvRowBytes[AVIF_CHAN_Y])];
const uint16_t * const ptrU = (uint16_t *)&image->yuvPlanes[AVIF_CHAN_U][(uvJ * image->yuvRowBytes[AVIF_CHAN_U])];
const uint16_t * const ptrV = (uint16_t *)&image->yuvPlanes[AVIF_CHAN_V][(uvJ * image->yuvRowBytes[AVIF_CHAN_V])];
uint8_t * ptrR = &rgb->pixels[state->rgbOffsetBytesR + (j * rgb->rowBytes)];
uint8_t * ptrG = &rgb->pixels[state->rgbOffsetBytesG + (j * rgb->rowBytes)];
uint8_t * ptrB = &rgb->pixels[state->rgbOffsetBytesB + (j * rgb->rowBytes)];
for (uint32_t i = 0; i < image->width; ++i) {
uint32_t uvI = i >> state->formatInfo.chromaShiftX;
// clamp incoming data to protect against bad LUT lookups
const uint16_t unormY = AVIF_MIN(ptrY[i], yuvMaxChannel);
const uint16_t unormU = AVIF_MIN(ptrU[uvI], yuvMaxChannel);
const uint16_t unormV = AVIF_MIN(ptrV[uvI], yuvMaxChannel);
// Convert unorm to float
const float Y = unormFloatTableY[unormY];
const float Cb = unormFloatTableUV[unormU];
const float Cr = unormFloatTableUV[unormV];
const float R = Y + (2 * (1 - kr)) * Cr;
const float B = Y + (2 * (1 - kb)) * Cb;
const float G = Y - ((2 * ((kr * (1 - kr) * Cr) + (kb * (1 - kb) * Cb))) / kg);
const float Rc = AVIF_CLAMP(R, 0.0f, 1.0f);
const float Gc = AVIF_CLAMP(G, 0.0f, 1.0f);
const float Bc = AVIF_CLAMP(B, 0.0f, 1.0f);
*((uint16_t *)ptrR) = (uint16_t)(0.5f + (Rc * rgbMaxChannelF));
*((uint16_t *)ptrG) = (uint16_t)(0.5f + (Gc * rgbMaxChannelF));
*((uint16_t *)ptrB) = (uint16_t)(0.5f + (Bc * rgbMaxChannelF));
ptrR += rgbPixelBytes;
ptrG += rgbPixelBytes;
ptrB += rgbPixelBytes;
}
}
return AVIF_RESULT_OK;
}
static avifResult avifImageYUV16ToRGB16Mono(const avifImage * image, avifRGBImage * rgb, avifReformatState * state)
{
const float kr = state->kr;
const float kg = state->kg;
const float kb = state->kb;
const uint32_t rgbPixelBytes = state->rgbPixelBytes;
const float * const unormFloatTableY = state->unormFloatTableY;
const uint16_t yuvMaxChannel = (uint16_t)state->yuvMaxChannel;
const float rgbMaxChannelF = state->rgbMaxChannelF;
for (uint32_t j = 0; j < image->height; ++j) {
const uint16_t * const ptrY = (uint16_t *)&image->yuvPlanes[AVIF_CHAN_Y][(j * image->yuvRowBytes[AVIF_CHAN_Y])];
uint8_t * ptrR = &rgb->pixels[state->rgbOffsetBytesR + (j * rgb->rowBytes)];
uint8_t * ptrG = &rgb->pixels[state->rgbOffsetBytesG + (j * rgb->rowBytes)];
uint8_t * ptrB = &rgb->pixels[state->rgbOffsetBytesB + (j * rgb->rowBytes)];
for (uint32_t i = 0; i < image->width; ++i) {
// clamp incoming data to protect against bad LUT lookups
const uint16_t unormY = AVIF_MIN(ptrY[i], yuvMaxChannel);
// Convert unorm to float
const float Y = unormFloatTableY[unormY];
const float Cb = 0.0f;
const float Cr = 0.0f;
const float R = Y + (2 * (1 - kr)) * Cr;
const float B = Y + (2 * (1 - kb)) * Cb;
const float G = Y - ((2 * ((kr * (1 - kr) * Cr) + (kb * (1 - kb) * Cb))) / kg);
const float Rc = AVIF_CLAMP(R, 0.0f, 1.0f);
const float Gc = AVIF_CLAMP(G, 0.0f, 1.0f);
const float Bc = AVIF_CLAMP(B, 0.0f, 1.0f);
*((uint16_t *)ptrR) = (uint16_t)(0.5f + (Rc * rgbMaxChannelF));
*((uint16_t *)ptrG) = (uint16_t)(0.5f + (Gc * rgbMaxChannelF));
*((uint16_t *)ptrB) = (uint16_t)(0.5f + (Bc * rgbMaxChannelF));
ptrR += rgbPixelBytes;
ptrG += rgbPixelBytes;
ptrB += rgbPixelBytes;
}
}
return AVIF_RESULT_OK;
}
static avifResult avifImageYUV16ToRGB8Color(const avifImage * image, avifRGBImage * rgb, avifReformatState * state)
{
const float kr = state->kr;
const float kg = state->kg;
const float kb = state->kb;
const uint32_t rgbPixelBytes = state->rgbPixelBytes;
const float * const unormFloatTableY = state->unormFloatTableY;
const float * const unormFloatTableUV = state->unormFloatTableUV;
const uint16_t yuvMaxChannel = (uint16_t)state->yuvMaxChannel;
const float rgbMaxChannelF = state->rgbMaxChannelF;
for (uint32_t j = 0; j < image->height; ++j) {
const uint32_t uvJ = j >> state->formatInfo.chromaShiftY;
const uint16_t * const ptrY = (uint16_t *)&image->yuvPlanes[AVIF_CHAN_Y][(j * image->yuvRowBytes[AVIF_CHAN_Y])];
const uint16_t * const ptrU = (uint16_t *)&image->yuvPlanes[AVIF_CHAN_U][(uvJ * image->yuvRowBytes[AVIF_CHAN_U])];
const uint16_t * const ptrV = (uint16_t *)&image->yuvPlanes[AVIF_CHAN_V][(uvJ * image->yuvRowBytes[AVIF_CHAN_V])];
uint8_t * ptrR = &rgb->pixels[state->rgbOffsetBytesR + (j * rgb->rowBytes)];
uint8_t * ptrG = &rgb->pixels[state->rgbOffsetBytesG + (j * rgb->rowBytes)];
uint8_t * ptrB = &rgb->pixels[state->rgbOffsetBytesB + (j * rgb->rowBytes)];
for (uint32_t i = 0; i < image->width; ++i) {
uint32_t uvI = i >> state->formatInfo.chromaShiftX;
// clamp incoming data to protect against bad LUT lookups
const uint16_t unormY = AVIF_MIN(ptrY[i], yuvMaxChannel);
const uint16_t unormU = AVIF_MIN(ptrU[uvI], yuvMaxChannel);
const uint16_t unormV = AVIF_MIN(ptrV[uvI], yuvMaxChannel);
// Convert unorm to float
const float Y = unormFloatTableY[unormY];
const float Cb = unormFloatTableUV[unormU];
const float Cr = unormFloatTableUV[unormV];
const float R = Y + (2 * (1 - kr)) * Cr;
const float B = Y + (2 * (1 - kb)) * Cb;
const float G = Y - ((2 * ((kr * (1 - kr) * Cr) + (kb * (1 - kb) * Cb))) / kg);
const float Rc = AVIF_CLAMP(R, 0.0f, 1.0f);
const float Gc = AVIF_CLAMP(G, 0.0f, 1.0f);
const float Bc = AVIF_CLAMP(B, 0.0f, 1.0f);
avifStoreRGB8Pixel(rgb->format,
(uint8_t)(0.5f + (Rc * rgbMaxChannelF)),
(uint8_t)(0.5f + (Gc * rgbMaxChannelF)),
(uint8_t)(0.5f + (Bc * rgbMaxChannelF)),
ptrR,
ptrG,
ptrB);
ptrR += rgbPixelBytes;
ptrG += rgbPixelBytes;
ptrB += rgbPixelBytes;
}
}
return AVIF_RESULT_OK;
}
static avifResult avifImageYUV16ToRGB8Mono(const avifImage * image, avifRGBImage * rgb, avifReformatState * state)
{
const float kr = state->kr;
const float kg = state->kg;
const float kb = state->kb;
const uint32_t rgbPixelBytes = state->rgbPixelBytes;
const float * const unormFloatTableY = state->unormFloatTableY;
const uint16_t yuvMaxChannel = (uint16_t)state->yuvMaxChannel;
const float rgbMaxChannelF = state->rgbMaxChannelF;
for (uint32_t j = 0; j < image->height; ++j) {
const uint16_t * const ptrY = (uint16_t *)&image->yuvPlanes[AVIF_CHAN_Y][(j * image->yuvRowBytes[AVIF_CHAN_Y])];
uint8_t * ptrR = &rgb->pixels[state->rgbOffsetBytesR + (j * rgb->rowBytes)];
uint8_t * ptrG = &rgb->pixels[state->rgbOffsetBytesG + (j * rgb->rowBytes)];
uint8_t * ptrB = &rgb->pixels[state->rgbOffsetBytesB + (j * rgb->rowBytes)];
for (uint32_t i = 0; i < image->width; ++i) {
// clamp incoming data to protect against bad LUT lookups
const uint16_t unormY = AVIF_MIN(ptrY[i], yuvMaxChannel);
// Convert unorm to float
const float Y = unormFloatTableY[unormY];
const float Cb = 0.0f;
const float Cr = 0.0f;
const float R = Y + (2 * (1 - kr)) * Cr;
const float B = Y + (2 * (1 - kb)) * Cb;
const float G = Y - ((2 * ((kr * (1 - kr) * Cr) + (kb * (1 - kb) * Cb))) / kg);
const float Rc = AVIF_CLAMP(R, 0.0f, 1.0f);
const float Gc = AVIF_CLAMP(G, 0.0f, 1.0f);
const float Bc = AVIF_CLAMP(B, 0.0f, 1.0f);
avifStoreRGB8Pixel(rgb->format,
(uint8_t)(0.5f + (Rc * rgbMaxChannelF)),
(uint8_t)(0.5f + (Gc * rgbMaxChannelF)),
(uint8_t)(0.5f + (Bc * rgbMaxChannelF)),
ptrR,
ptrG,
ptrB);
ptrR += rgbPixelBytes;
ptrG += rgbPixelBytes;
ptrB += rgbPixelBytes;
}
}
return AVIF_RESULT_OK;
}
static avifResult avifImageYUV8ToRGB16Color(const avifImage * image, avifRGBImage * rgb, avifReformatState * state)
{
const float kr = state->kr;
const float kg = state->kg;
const float kb = state->kb;
const uint32_t rgbPixelBytes = state->rgbPixelBytes;
const float * const unormFloatTableY = state->unormFloatTableY;
const float * const unormFloatTableUV = state->unormFloatTableUV;
const float rgbMaxChannelF = state->rgbMaxChannelF;
for (uint32_t j = 0; j < image->height; ++j) {
const uint32_t uvJ = j >> state->formatInfo.chromaShiftY;
const uint8_t * const ptrY = &image->yuvPlanes[AVIF_CHAN_Y][(j * image->yuvRowBytes[AVIF_CHAN_Y])];
const uint8_t * const ptrU = &image->yuvPlanes[AVIF_CHAN_U][(uvJ * image->yuvRowBytes[AVIF_CHAN_U])];
const uint8_t * const ptrV = &image->yuvPlanes[AVIF_CHAN_V][(uvJ * image->yuvRowBytes[AVIF_CHAN_V])];
uint8_t * ptrR = &rgb->pixels[state->rgbOffsetBytesR + (j * rgb->rowBytes)];
uint8_t * ptrG = &rgb->pixels[state->rgbOffsetBytesG + (j * rgb->rowBytes)];
uint8_t * ptrB = &rgb->pixels[state->rgbOffsetBytesB + (j * rgb->rowBytes)];
for (uint32_t i = 0; i < image->width; ++i) {
uint32_t uvI = i >> state->formatInfo.chromaShiftX;
// Convert unorm to float (no clamp necessary, the full uint8_t range is a legal lookup)
const float Y = unormFloatTableY[ptrY[i]];
const float Cb = unormFloatTableUV[ptrU[uvI]];
const float Cr = unormFloatTableUV[ptrV[uvI]];
const float R = Y + (2 * (1 - kr)) * Cr;
const float B = Y + (2 * (1 - kb)) * Cb;
const float G = Y - ((2 * ((kr * (1 - kr) * Cr) + (kb * (1 - kb) * Cb))) / kg);
const float Rc = AVIF_CLAMP(R, 0.0f, 1.0f);
const float Gc = AVIF_CLAMP(G, 0.0f, 1.0f);
const float Bc = AVIF_CLAMP(B, 0.0f, 1.0f);
*((uint16_t *)ptrR) = (uint16_t)(0.5f + (Rc * rgbMaxChannelF));
*((uint16_t *)ptrG) = (uint16_t)(0.5f + (Gc * rgbMaxChannelF));
*((uint16_t *)ptrB) = (uint16_t)(0.5f + (Bc * rgbMaxChannelF));
ptrR += rgbPixelBytes;
ptrG += rgbPixelBytes;
ptrB += rgbPixelBytes;
}
}
return AVIF_RESULT_OK;
}
static avifResult avifImageYUV8ToRGB16Mono(const avifImage * image, avifRGBImage * rgb, avifReformatState * state)
{
const float kr = state->kr;
const float kg = state->kg;
const float kb = state->kb;
const uint32_t rgbPixelBytes = state->rgbPixelBytes;
const float * const unormFloatTableY = state->unormFloatTableY;
const float rgbMaxChannelF = state->rgbMaxChannelF;
for (uint32_t j = 0; j < image->height; ++j) {
const uint8_t * const ptrY = &image->yuvPlanes[AVIF_CHAN_Y][(j * image->yuvRowBytes[AVIF_CHAN_Y])];
uint8_t * ptrR = &rgb->pixels[state->rgbOffsetBytesR + (j * rgb->rowBytes)];
uint8_t * ptrG = &rgb->pixels[state->rgbOffsetBytesG + (j * rgb->rowBytes)];
uint8_t * ptrB = &rgb->pixels[state->rgbOffsetBytesB + (j * rgb->rowBytes)];
for (uint32_t i = 0; i < image->width; ++i) {
// Convert unorm to float (no clamp necessary, the full uint8_t range is a legal lookup)
const float Y = unormFloatTableY[ptrY[i]];
const float Cb = 0.0f;
const float Cr = 0.0f;
const float R = Y + (2 * (1 - kr)) * Cr;
const float B = Y + (2 * (1 - kb)) * Cb;
const float G = Y - ((2 * ((kr * (1 - kr) * Cr) + (kb * (1 - kb) * Cb))) / kg);
const float Rc = AVIF_CLAMP(R, 0.0f, 1.0f);
const float Gc = AVIF_CLAMP(G, 0.0f, 1.0f);
const float Bc = AVIF_CLAMP(B, 0.0f, 1.0f);
*((uint16_t *)ptrR) = (uint16_t)(0.5f + (Rc * rgbMaxChannelF));
*((uint16_t *)ptrG) = (uint16_t)(0.5f + (Gc * rgbMaxChannelF));
*((uint16_t *)ptrB) = (uint16_t)(0.5f + (Bc * rgbMaxChannelF));
ptrR += rgbPixelBytes;
ptrG += rgbPixelBytes;
ptrB += rgbPixelBytes;
}
}
return AVIF_RESULT_OK;
}
static avifResult avifImageIdentity8ToRGB8ColorFullRange(const avifImage * image, avifRGBImage * rgb, avifReformatState * state)
{
const uint32_t rgbPixelBytes = state->rgbPixelBytes;
for (uint32_t j = 0; j < image->height; ++j) {
const uint8_t * const ptrY = &image->yuvPlanes[AVIF_CHAN_Y][(j * image->yuvRowBytes[AVIF_CHAN_Y])];
const uint8_t * const ptrU = &image->yuvPlanes[AVIF_CHAN_U][(j * image->yuvRowBytes[AVIF_CHAN_U])];
const uint8_t * const ptrV = &image->yuvPlanes[AVIF_CHAN_V][(j * image->yuvRowBytes[AVIF_CHAN_V])];
uint8_t * ptrR = &rgb->pixels[state->rgbOffsetBytesR + (j * rgb->rowBytes)];
uint8_t * ptrG = &rgb->pixels[state->rgbOffsetBytesG + (j * rgb->rowBytes)];
uint8_t * ptrB = &rgb->pixels[state->rgbOffsetBytesB + (j * rgb->rowBytes)];
// This is intentionally a per-row conditional instead of a per-pixel
// conditional. This makes the "else" path (much more common than the
// "if" path) much faster than having a per-pixel branch.
if (rgb->format == AVIF_RGB_FORMAT_RGB_565) {
for (uint32_t i = 0; i < image->width; ++i) {
*(uint16_t *)ptrR = RGB565(ptrV[i], ptrY[i], ptrU[i]);
ptrR += rgbPixelBytes;
}
} else {
for (uint32_t i = 0; i < image->width; ++i) {
*ptrR = ptrV[i];
*ptrG = ptrY[i];
*ptrB = ptrU[i];
ptrR += rgbPixelBytes;
ptrG += rgbPixelBytes;
ptrB += rgbPixelBytes;
}
}
}
return AVIF_RESULT_OK;
}
static avifResult avifImageYUV8ToRGB8Color(const avifImage * image, avifRGBImage * rgb, avifReformatState * state)
{
const float kr = state->kr;
const float kg = state->kg;
const float kb = state->kb;
const uint32_t rgbPixelBytes = state->rgbPixelBytes;
const float * const unormFloatTableY = state->unormFloatTableY;
const float * const unormFloatTableUV = state->unormFloatTableUV;
const float rgbMaxChannelF = state->rgbMaxChannelF;
for (uint32_t j = 0; j < image->height; ++j) {
const uint32_t uvJ = j >> state->formatInfo.chromaShiftY;
const uint8_t * const ptrY = &image->yuvPlanes[AVIF_CHAN_Y][(j * image->yuvRowBytes[AVIF_CHAN_Y])];
const uint8_t * const ptrU = &image->yuvPlanes[AVIF_CHAN_U][(uvJ * image->yuvRowBytes[AVIF_CHAN_U])];
const uint8_t * const ptrV = &image->yuvPlanes[AVIF_CHAN_V][(uvJ * image->yuvRowBytes[AVIF_CHAN_V])];
uint8_t * ptrR = &rgb->pixels[state->rgbOffsetBytesR + (j * rgb->rowBytes)];
uint8_t * ptrG = &rgb->pixels[state->rgbOffsetBytesG + (j * rgb->rowBytes)];
uint8_t * ptrB = &rgb->pixels[state->rgbOffsetBytesB + (j * rgb->rowBytes)];
for (uint32_t i = 0; i < image->width; ++i) {
uint32_t uvI = i >> state->formatInfo.chromaShiftX;
// Convert unorm to float (no clamp necessary, the full uint8_t range is a legal lookup)
const float Y = unormFloatTableY[ptrY[i]];
const float Cb = unormFloatTableUV[ptrU[uvI]];
const float Cr = unormFloatTableUV[ptrV[uvI]];
const float R = Y + (2 * (1 - kr)) * Cr;
const float B = Y + (2 * (1 - kb)) * Cb;
const float G = Y - ((2 * ((kr * (1 - kr) * Cr) + (kb * (1 - kb) * Cb))) / kg);
const float Rc = AVIF_CLAMP(R, 0.0f, 1.0f);
const float Gc = AVIF_CLAMP(G, 0.0f, 1.0f);
const float Bc = AVIF_CLAMP(B, 0.0f, 1.0f);
avifStoreRGB8Pixel(rgb->format,
(uint8_t)(0.5f + (Rc * rgbMaxChannelF)),
(uint8_t)(0.5f + (Gc * rgbMaxChannelF)),
(uint8_t)(0.5f + (Bc * rgbMaxChannelF)),
ptrR,
ptrG,
ptrB);
ptrR += rgbPixelBytes;
ptrG += rgbPixelBytes;
ptrB += rgbPixelBytes;
}
}
return AVIF_RESULT_OK;
}
static avifResult avifImageYUV8ToRGB8Mono(const avifImage * image, avifRGBImage * rgb, avifReformatState * state)
{
const float kr = state->kr;
const float kg = state->kg;
const float kb = state->kb;
const uint32_t rgbPixelBytes = state->rgbPixelBytes;
const float * const unormFloatTableY = state->unormFloatTableY;
const float rgbMaxChannelF = state->rgbMaxChannelF;
for (uint32_t j = 0; j < image->height; ++j) {
const uint8_t * const ptrY = &image->yuvPlanes[AVIF_CHAN_Y][(j * image->yuvRowBytes[AVIF_CHAN_Y])];
uint8_t * ptrR = &rgb->pixels[state->rgbOffsetBytesR + (j * rgb->rowBytes)];
uint8_t * ptrG = &rgb->pixels[state->rgbOffsetBytesG + (j * rgb->rowBytes)];
uint8_t * ptrB = &rgb->pixels[state->rgbOffsetBytesB + (j * rgb->rowBytes)];
for (uint32_t i = 0; i < image->width; ++i) {
// Convert unorm to float (no clamp necessary, the full uint8_t range is a legal lookup)
const float Y = unormFloatTableY[ptrY[i]];
const float Cb = 0.0f;
const float Cr = 0.0f;
const float R = Y + (2 * (1 - kr)) * Cr;
const float B = Y + (2 * (1 - kb)) * Cb;
const float G = Y - ((2 * ((kr * (1 - kr) * Cr) + (kb * (1 - kb) * Cb))) / kg);
const float Rc = AVIF_CLAMP(R, 0.0f, 1.0f);
const float Gc = AVIF_CLAMP(G, 0.0f, 1.0f);
const float Bc = AVIF_CLAMP(B, 0.0f, 1.0f);
avifStoreRGB8Pixel(rgb->format,
(uint8_t)(0.5f + (Rc * rgbMaxChannelF)),
(uint8_t)(0.5f + (Gc * rgbMaxChannelF)),
(uint8_t)(0.5f + (Bc * rgbMaxChannelF)),
ptrR,
ptrG,
ptrB);
ptrR += rgbPixelBytes;
ptrG += rgbPixelBytes;
ptrB += rgbPixelBytes;
}
}
return AVIF_RESULT_OK;
}
static avifResult avifRGBImageToF16(avifRGBImage * rgb)
{
avifResult libyuvResult = AVIF_RESULT_NOT_IMPLEMENTED;
if (!rgb->avoidLibYUV) {
libyuvResult = avifRGBImageToF16LibYUV(rgb);
}
if (libyuvResult != AVIF_RESULT_NOT_IMPLEMENTED) {
return libyuvResult;
}
const uint32_t channelCount = avifRGBFormatChannelCount(rgb->format);
const float scale = 1.0f / ((1 << rgb->depth) - 1);
// This constant comes from libyuv. For details, see here:
// https://chromium.googlesource.com/libyuv/libyuv/+/2f87e9a7/source/row_common.cc#3537
const float multiplier = 1.9259299444e-34f * scale;
uint16_t * pixelRowBase = (uint16_t *)rgb->pixels;
const uint32_t stride = rgb->rowBytes >> 1;
for (uint32_t j = 0; j < rgb->height; ++j) {
uint16_t * pixel = pixelRowBase;
for (uint32_t i = 0; i < rgb->width * channelCount; ++i, ++pixel) {
union
{
float f;
uint32_t u32;
} f16;
f16.f = *pixel * multiplier;
*pixel = (uint16_t)(f16.u32 >> 13);
}
pixelRowBase += stride;
}
return AVIF_RESULT_OK;
}
avifResult avifImageYUVToRGB(const avifImage * image, avifRGBImage * rgb)
{
if (!image->yuvPlanes[AVIF_CHAN_Y]) {
return AVIF_RESULT_REFORMAT_FAILED;
}
avifReformatState state;
if (!avifPrepareReformatState(image, rgb, &state)) {
return AVIF_RESULT_REFORMAT_FAILED;
}
avifAlphaMultiplyMode alphaMultiplyMode = state.toRGBAlphaMode;
avifBool convertedWithLibYUV = AVIF_FALSE;
if (!rgb->avoidLibYUV && ((alphaMultiplyMode == AVIF_ALPHA_MULTIPLY_MODE_NO_OP) || avifRGBFormatHasAlpha(rgb->format))) {
avifResult libyuvResult = avifImageYUVToRGBLibYUV(image, rgb);
if (libyuvResult == AVIF_RESULT_OK) {
convertedWithLibYUV = AVIF_TRUE;
} else {
if (libyuvResult != AVIF_RESULT_NOT_IMPLEMENTED) {
return libyuvResult;
}
}
}
// Reformat alpha, if user asks for it, or (un)multiply processing needs it.
if (avifRGBFormatHasAlpha(rgb->format) && (!rgb->ignoreAlpha || (alphaMultiplyMode != AVIF_ALPHA_MULTIPLY_MODE_NO_OP))) {
avifAlphaParams params;
params.width = rgb->width;
params.height = rgb->height;
params.dstDepth = rgb->depth;
params.dstPlane = rgb->pixels;
params.dstRowBytes = rgb->rowBytes;
params.dstOffsetBytes = state.rgbOffsetBytesA;
params.dstPixelBytes = state.rgbPixelBytes;
if (image->alphaPlane && image->alphaRowBytes) {
params.srcDepth = image->depth;
params.srcPlane = image->alphaPlane;
params.srcRowBytes = image->alphaRowBytes;
params.srcOffsetBytes = 0;
params.srcPixelBytes = state.yuvChannelBytes;
avifReformatAlpha(¶ms);
} else {
if (!convertedWithLibYUV) { // libyuv fills alpha for us
avifFillAlpha(¶ms);
}
}
}
if (!convertedWithLibYUV) {
// libyuv is either unavailable or unable to perform the specific conversion required here.
// Look over the available built-in "fast" routines for YUV->RGB conversion and see if one
// fits the current combination, or as a last resort, call avifImageYUVAnyToRGBAnySlow(),
// which handles every possibly YUV->RGB combination, but very slowly (in comparison).
avifResult convertResult = AVIF_RESULT_NOT_IMPLEMENTED;
const avifBool hasColor =
(image->yuvRowBytes[AVIF_CHAN_U] && image->yuvRowBytes[AVIF_CHAN_V] && (image->yuvFormat != AVIF_PIXEL_FORMAT_YUV400));
if ((!hasColor || (image->yuvFormat == AVIF_PIXEL_FORMAT_YUV444) ||
((rgb->chromaUpsampling == AVIF_CHROMA_UPSAMPLING_FASTEST) || (rgb->chromaUpsampling == AVIF_CHROMA_UPSAMPLING_NEAREST))) &&
(alphaMultiplyMode == AVIF_ALPHA_MULTIPLY_MODE_NO_OP || avifRGBFormatHasAlpha(rgb->format))) {
// Explanations on the above conditional:
// * None of these fast paths currently support bilinear upsampling, so avoid all of them
// unless the YUV data isn't subsampled or they explicitly requested AVIF_CHROMA_UPSAMPLING_NEAREST.
// * None of these fast paths currently handle alpha (un)multiply, so avoid all of them
// if we can't do alpha (un)multiply as a separated post step (destination format doesn't have alpha).
if (state.mode == AVIF_REFORMAT_MODE_IDENTITY) {
if ((image->depth == 8) && (rgb->depth == 8) && (image->yuvFormat == AVIF_PIXEL_FORMAT_YUV444) &&
(image->yuvRange == AVIF_RANGE_FULL)) {
convertResult = avifImageIdentity8ToRGB8ColorFullRange(image, rgb, &state);
}
// TODO: Add more fast paths for identity
} else if (state.mode == AVIF_REFORMAT_MODE_YUV_COEFFICIENTS) {
if (image->depth > 8) {
// yuv:u16
if (rgb->depth > 8) {
// yuv:u16, rgb:u16
if (hasColor) {
convertResult = avifImageYUV16ToRGB16Color(image, rgb, &state);
} else {
convertResult = avifImageYUV16ToRGB16Mono(image, rgb, &state);
}
} else {
// yuv:u16, rgb:u8
if (hasColor) {
convertResult = avifImageYUV16ToRGB8Color(image, rgb, &state);
} else {
convertResult = avifImageYUV16ToRGB8Mono(image, rgb, &state);
}
}
} else {
// yuv:u8
if (rgb->depth > 8) {
// yuv:u8, rgb:u16
if (hasColor) {
convertResult = avifImageYUV8ToRGB16Color(image, rgb, &state);
} else {
convertResult = avifImageYUV8ToRGB16Mono(image, rgb, &state);
}
} else {
// yuv:u8, rgb:u8
if (hasColor) {
convertResult = avifImageYUV8ToRGB8Color(image, rgb, &state);
} else {
convertResult = avifImageYUV8ToRGB8Mono(image, rgb, &state);
}
}
}
}
}
if (convertResult == AVIF_RESULT_NOT_IMPLEMENTED) {
// If we get here, there is no fast path for this combination. Time to be slow!
convertResult = avifImageYUVAnyToRGBAnySlow(image, rgb, &state);
// The slow path also handles alpha (un)multiply, so forget the operation here.
alphaMultiplyMode = AVIF_ALPHA_MULTIPLY_MODE_NO_OP;
}
if (convertResult != AVIF_RESULT_OK) {
return convertResult;
}
}
// Process alpha premultiplication, if necessary
if (alphaMultiplyMode == AVIF_ALPHA_MULTIPLY_MODE_MULTIPLY) {
avifResult result = avifRGBImagePremultiplyAlpha(rgb);
if (result != AVIF_RESULT_OK) {
return result;
}
} else if (alphaMultiplyMode == AVIF_ALPHA_MULTIPLY_MODE_UNMULTIPLY) {
avifResult result = avifRGBImageUnpremultiplyAlpha(rgb);
if (result != AVIF_RESULT_OK) {
return result;
}
}
// Convert pixels to half floats (F16), if necessary.
if (rgb->isFloat) {
return avifRGBImageToF16(rgb);
}
return AVIF_RESULT_OK;
}
// Limited -> Full
// Plan: subtract limited offset, then multiply by ratio of FULLSIZE/LIMITEDSIZE (rounding), then clamp.
// RATIO = (FULLY - 0) / (MAXLIMITEDY - MINLIMITEDY)
// -----------------------------------------
// ( ( (v - MINLIMITEDY) | subtract limited offset
// * FULLY | multiply numerator of ratio
// ) + ((MAXLIMITEDY - MINLIMITEDY) / 2) | add 0.5 (half of denominator) to round
// ) / (MAXLIMITEDY - MINLIMITEDY) | divide by denominator of ratio
// AVIF_CLAMP(v, 0, FULLY) | clamp to full range
// -----------------------------------------
#define LIMITED_TO_FULL(MINLIMITEDY, MAXLIMITEDY, FULLY) \
v = (((v - MINLIMITEDY) * FULLY) + ((MAXLIMITEDY - MINLIMITEDY) / 2)) / (MAXLIMITEDY - MINLIMITEDY); \
v = AVIF_CLAMP(v, 0, FULLY)
// Full -> Limited
// Plan: multiply by ratio of LIMITEDSIZE/FULLSIZE (rounding), then add limited offset, then clamp.
// RATIO = (MAXLIMITEDY - MINLIMITEDY) / (FULLY - 0)
// -----------------------------------------
// ( ( (v * (MAXLIMITEDY - MINLIMITEDY)) | multiply numerator of ratio
// + (FULLY / 2) | add 0.5 (half of denominator) to round
// ) / FULLY | divide by denominator of ratio
// ) + MINLIMITEDY | add limited offset
// AVIF_CLAMP(v, MINLIMITEDY, MAXLIMITEDY) | clamp to limited range
// -----------------------------------------
#define FULL_TO_LIMITED(MINLIMITEDY, MAXLIMITEDY, FULLY) \
v = (((v * (MAXLIMITEDY - MINLIMITEDY)) + (FULLY / 2)) / FULLY) + MINLIMITEDY; \
v = AVIF_CLAMP(v, MINLIMITEDY, MAXLIMITEDY)
int avifLimitedToFullY(int depth, int v)
{
switch (depth) {
case 8:
LIMITED_TO_FULL(16, 235, 255);
break;
case 10:
LIMITED_TO_FULL(64, 940, 1023);
break;
case 12:
LIMITED_TO_FULL(256, 3760, 4095);
break;
}
return v;
}
int avifLimitedToFullUV(int depth, int v)
{
switch (depth) {
case 8:
LIMITED_TO_FULL(16, 240, 255);
break;
case 10:
LIMITED_TO_FULL(64, 960, 1023);
break;
case 12:
LIMITED_TO_FULL(256, 3840, 4095);
break;
}
return v;
}
int avifFullToLimitedY(int depth, int v)
{
switch (depth) {
case 8:
FULL_TO_LIMITED(16, 235, 255);
break;
case 10:
FULL_TO_LIMITED(64, 940, 1023);
break;
case 12:
FULL_TO_LIMITED(256, 3760, 4095);
break;
}
return v;
}
int avifFullToLimitedUV(int depth, int v)
{
switch (depth) {
case 8:
FULL_TO_LIMITED(16, 240, 255);
break;
case 10:
FULL_TO_LIMITED(64, 960, 1023);
break;
case 12:
FULL_TO_LIMITED(256, 3840, 4095);
break;
}
return v;
}