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Use SkSwizzler to convert from CMYK

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Move convert_CMYK_to_RGBA into two functions in SkSwizzler: one for 565
and one for 8888.

For simplicity, when converting to 8888, we no longer convert in place.

BUG=skia:4476

Committed: https://skia.googlesource.com/skia/+/450ee8f26d39f975cf6af37a27de658ae5a9fa10

Review URL: https://codereview.chromium.org/1411083009
This commit is contained in:
scroggo 2015-10-23 09:29:22 -07:00 committed by Commit bot
parent 19e82e3b9f
commit ef27d89b07
4 changed files with 145 additions and 100 deletions
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145
src/codec/SkJpegCodec.cpp
View File

@ -23,69 +23,6 @@ extern "C" {
#include "jpeglib.h"
}
/*
* Convert a row of CMYK samples to RGBA in place.
* Note that this method moves the row pointer.
* @param width the number of pixels in the row that is being converted
* CMYK is stored as four bytes per pixel
*/
static void convert_CMYK_to_RGBA(uint8_t* row, uint32_t width) {
// We will implement a crude conversion from CMYK -> RGB using formulas
// from easyrgb.com.
//
// CMYK -> CMY
// C = C * (1 - K) + K
// M = M * (1 - K) + K
// Y = Y * (1 - K) + K
//
// libjpeg actually gives us inverted CMYK, so we must subtract the
// original terms from 1.
// CMYK -> CMY
// C = (1 - C) * (1 - (1 - K)) + (1 - K)
// M = (1 - M) * (1 - (1 - K)) + (1 - K)
// Y = (1 - Y) * (1 - (1 - K)) + (1 - K)
//
// Simplifying the above expression.
// CMYK -> CMY
// C = 1 - CK
// M = 1 - MK
// Y = 1 - YK
//
// CMY -> RGB
// R = (1 - C) * 255
// G = (1 - M) * 255
// B = (1 - Y) * 255
//
// Therefore the full conversion is below. This can be verified at
// www.rapidtables.com (assuming inverted CMYK).
// CMYK -> RGB
// R = C * K * 255
// G = M * K * 255
// B = Y * K * 255
//
// As a final note, we have treated the CMYK values as if they were on
// a scale from 0-1, when in fact they are 8-bit ints scaling from 0-255.
// We must divide each CMYK component by 255 to obtain the true conversion
// we should perform.
// CMYK -> RGB
// R = C * K / 255
// G = M * K / 255
// B = Y * K / 255
for (uint32_t x = 0; x < width; x++, row += 4) {
#if defined(SK_PMCOLOR_IS_RGBA)
row[0] = SkMulDiv255Round(row[0], row[3]);
row[1] = SkMulDiv255Round(row[1], row[3]);
row[2] = SkMulDiv255Round(row[2], row[3]);
#else
uint8_t tmp = row[0];
row[0] = SkMulDiv255Round(row[2], row[3]);
row[1] = SkMulDiv255Round(row[1], row[3]);
row[2] = SkMulDiv255Round(tmp, row[3]);
#endif
row[3] = 0xFF;
}
}
bool SkJpegCodec::IsJpeg(SkStream* stream) {
static const uint8_t jpegSig[] = { 0xFF, 0xD8, 0xFF };
char buffer[sizeof(jpegSig)];
@ -263,10 +200,7 @@ bool SkJpegCodec::setOutputColorSpace(const SkImageInfo& dst) {
return true;
case kRGB_565_SkColorType:
if (isCMYK) {
// FIXME (msarett): We need to support 565 here. It's not hard to do, considering
// we already convert CMYK to RGBA, I just need to do it. I think it might be
// best to do this in SkSwizzler and also move convert_CMYK_to_RGBA into SkSwizzler.
return false;
fDecoderMgr->dinfo()->out_color_space = JCS_CMYK;
} else {
#if defined(GOOGLE3)
return false;
@ -365,9 +299,22 @@ SkCodec::Result SkJpegCodec::onGetPixels(const SkImageInfo& dstInfo,
// If it's not, we want to know because it means our strategy is not optimal.
SkASSERT(1 == dinfo->rec_outbuf_height);
if (JCS_CMYK == dinfo->out_color_space) {
this->initializeSwizzler(dstInfo, options);
}
// Perform the decode a single row at a time
uint32_t dstHeight = dstInfo.height();
JSAMPLE* dstRow = (JSAMPLE*) dst;
JSAMPLE* dstRow;
if (fSwizzler) {
// write data to storage row, then sample using swizzler
dstRow = fSrcRow;
} else {
// write data directly to dst
dstRow = (JSAMPLE*) dst;
}
for (uint32_t y = 0; y < dstHeight; y++) {
// Read rows of the image
uint32_t lines = jpeg_read_scanlines(dinfo, &dstRow, 1);
@ -379,13 +326,13 @@ SkCodec::Result SkJpegCodec::onGetPixels(const SkImageInfo& dstInfo,
return fDecoderMgr->returnFailure("Incomplete image data", kIncompleteInput);
}
// Convert to RGBA if necessary
if (JCS_CMYK == dinfo->out_color_space) {
convert_CMYK_to_RGBA(dstRow, dstInfo.width());
if (fSwizzler) {
// use swizzler to sample row
fSwizzler->swizzle(dst, dstRow);
dst = SkTAddOffset<JSAMPLE>(dst, dstRowBytes);
} else {
dstRow = SkTAddOffset<JSAMPLE>(dstRow, dstRowBytes);
}
// Move to the next row
dstRow = SkTAddOffset<JSAMPLE>(dstRow, dstRowBytes);
}
return kSuccess;
@ -393,26 +340,30 @@ SkCodec::Result SkJpegCodec::onGetPixels(const SkImageInfo& dstInfo,
void SkJpegCodec::initializeSwizzler(const SkImageInfo& dstInfo, const Options& options) {
SkSwizzler::SrcConfig srcConfig = SkSwizzler::kUnknown;
switch (dstInfo.colorType()) {
case kGray_8_SkColorType:
srcConfig = SkSwizzler::kGray;
break;
case kRGBA_8888_SkColorType:
srcConfig = SkSwizzler::kRGBX;
break;
case kBGRA_8888_SkColorType:
srcConfig = SkSwizzler::kBGRX;
break;
case kRGB_565_SkColorType:
srcConfig = SkSwizzler::kRGB_565;
break;
default:
// This function should only be called if the colorType is supported by jpeg
if (JCS_CMYK == fDecoderMgr->dinfo()->out_color_space) {
srcConfig = SkSwizzler::kCMYK;
} else {
switch (dstInfo.colorType()) {
case kGray_8_SkColorType:
srcConfig = SkSwizzler::kGray;
break;
case kRGBA_8888_SkColorType:
srcConfig = SkSwizzler::kRGBX;
break;
case kBGRA_8888_SkColorType:
srcConfig = SkSwizzler::kBGRX;
break;
case kRGB_565_SkColorType:
srcConfig = SkSwizzler::kRGB_565;
break;
default:
// This function should only be called if the colorType is supported by jpeg
#if defined(GOOGLE3)
SK_CRASH();
SK_CRASH();
#else
SkASSERT(false);
SkASSERT(false);
#endif
}
}
fSwizzler.reset(SkSwizzler::CreateSwizzler(srcConfig, nullptr, dstInfo, options));
@ -454,8 +405,9 @@ SkCodec::Result SkJpegCodec::onStartScanlineDecode(const SkImageInfo& dstInfo,
return kInvalidInput;
}
// We will need a swizzler if we are performing a subset decode
if (options.fSubset) {
// We will need a swizzler if we are performing a subset decode or
// converting from CMYK.
if (options.fSubset || JCS_CMYK == fDecoderMgr->dinfo()->out_color_space) {
this->initializeSwizzler(dstInfo, options);
}
@ -485,12 +437,7 @@ int SkJpegCodec::onGetScanlines(void* dst, int count, size_t rowBytes) {
return y;
}
// Convert to RGBA if necessary
if (JCS_CMYK == fDecoderMgr->dinfo()->out_color_space) {
convert_CMYK_to_RGBA(dstRow, fDecoderMgr->dinfo()->output_width);
}
if(fSwizzler) {
if (fSwizzler) {
// use swizzler to sample row
fSwizzler->swizzle(dst, dstRow);
dst = SkTAddOffset<JSAMPLE>(dst, rowBytes);

96
src/codec/SkSwizzler.cpp
View File

@ -480,6 +480,89 @@ static SkSwizzler::ResultAlpha swizzle_rgba_to_n32_premul_skipZ(
return COMPUTE_RESULT_ALPHA;
}
// kCMYK
//
// CMYK is stored as four bytes per pixel.
//
// We will implement a crude conversion from CMYK -> RGB using formulas
// from easyrgb.com.
//
// CMYK -> CMY
// C = C * (1 - K) + K
// M = M * (1 - K) + K
// Y = Y * (1 - K) + K
//
// libjpeg actually gives us inverted CMYK, so we must subtract the
// original terms from 1.
// CMYK -> CMY
// C = (1 - C) * (1 - (1 - K)) + (1 - K)
// M = (1 - M) * (1 - (1 - K)) + (1 - K)
// Y = (1 - Y) * (1 - (1 - K)) + (1 - K)
//
// Simplifying the above expression.
// CMYK -> CMY
// C = 1 - CK
// M = 1 - MK
// Y = 1 - YK
//
// CMY -> RGB
// R = (1 - C) * 255
// G = (1 - M) * 255
// B = (1 - Y) * 255
//
// Therefore the full conversion is below. This can be verified at
// www.rapidtables.com (assuming inverted CMYK).
// CMYK -> RGB
// R = C * K * 255
// G = M * K * 255
// B = Y * K * 255
//
// As a final note, we have treated the CMYK values as if they were on
// a scale from 0-1, when in fact they are 8-bit ints scaling from 0-255.
// We must divide each CMYK component by 255 to obtain the true conversion
// we should perform.
// CMYK -> RGB
// R = C * K / 255
// G = M * K / 255
// B = Y * K / 255
static SkSwizzler::ResultAlpha swizzle_cmyk_to_n32(
void* SK_RESTRICT dstRow, const uint8_t* SK_RESTRICT src, int dstWidth,
int bpp, int deltaSrc, int offset, const SkPMColor ctable[]) {
src += offset;
SkPMColor* SK_RESTRICT dst = (SkPMColor*)dstRow;
for (int x = 0; x < dstWidth; x++) {
const uint8_t r = SkMulDiv255Round(src[0], src[3]);
const uint8_t g = SkMulDiv255Round(src[1], src[3]);
const uint8_t b = SkMulDiv255Round(src[2], src[3]);
dst[x] = SkPackARGB32NoCheck(0xFF, r, g, b);
src += deltaSrc;
}
// CMYK is always opaque
return SkSwizzler::kOpaque_ResultAlpha;
}
static SkSwizzler::ResultAlpha swizzle_cmyk_to_565(
void* SK_RESTRICT dstRow, const uint8_t* SK_RESTRICT src, int dstWidth,
int bpp, int deltaSrc, int offset, const SkPMColor ctable[]) {
src += offset;
uint16_t* SK_RESTRICT dst = (uint16_t*)dstRow;
for (int x = 0; x < dstWidth; x++) {
const uint8_t r = SkMulDiv255Round(src[0], src[3]);
const uint8_t g = SkMulDiv255Round(src[1], src[3]);
const uint8_t b = SkMulDiv255Round(src[2], src[3]);
dst[x] = SkPack888ToRGB16(r, g, b);
src += deltaSrc;
}
// CMYK is always opaque
return SkSwizzler::kOpaque_ResultAlpha;
}
/**
FIXME: This was my idea to cheat in order to continue taking advantage of skipping zeroes.
This would be fine for drawing normally, but not for drawing with transfer modes. Being
@ -672,6 +755,19 @@ SkSwizzler* SkSwizzler::CreateSwizzler(SkSwizzler::SrcConfig sc,
default:
break;
}
break;
case kCMYK:
switch (dstInfo.colorType()) {
case kN32_SkColorType:
proc = &swizzle_cmyk_to_n32;
break;
case kRGB_565_SkColorType:
proc = &swizzle_cmyk_to_565;
break;
default:
break;
}
break;
default:
break;
}

2
src/codec/SkSwizzler.h
View File

@ -33,6 +33,7 @@ public:
kRGBA,
kBGRA,
kRGB_565,
kCMYK,
};
/*
@ -97,6 +98,7 @@ public:
case kRGBA:
case kBGRX:
case kBGRA:
case kCMYK:
return 32;
default:
SkASSERT(false);

2
tests/CodexTest.cpp
View File

@ -408,7 +408,7 @@ DEF_TEST(Codec, r) {
check(r, "randPixels.gif", SkISize::Make(8, 8), true, false, true, false);
// JPG
check(r, "CMYK.jpg", SkISize::Make(642, 516), true, false, false);
check(r, "CMYK.jpg", SkISize::Make(642, 516), true, false, true);
check(r, "color_wheel.jpg", SkISize::Make(128, 128), true, false);
// grayscale.jpg is too small to test incomplete
check(r, "grayscale.jpg", SkISize::Make(128, 128), true, false, true, false);