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Unified Diff: src/codec/SkJpegCodec.cpp

Issue 1411193006: Revert of Use SkSwizzler to convert from CMYK (Closed) Base URL: https://skia.googlesource.com/skia.git@NewFromData
Patch Set: Created 5 years, 2 months ago
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Index: src/codec/SkJpegCodec.cpp
diff --git a/src/codec/SkJpegCodec.cpp b/src/codec/SkJpegCodec.cpp
index 6850a7782512aa0cc731982c7fb3cff61c93b0ec..9975748cf4b4ce4010ea9dc79eca8cac6614fc93 100644
--- a/src/codec/SkJpegCodec.cpp
+++ b/src/codec/SkJpegCodec.cpp
@@ -21,6 +21,69 @@
extern "C" {
#include "jerror.h"
#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) {
@@ -200,7 +263,10 @@
return true;
case kRGB_565_SkColorType:
if (isCMYK) {
- fDecoderMgr->dinfo()->out_color_space = JCS_CMYK;
+ // 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;
} else {
#if defined(GOOGLE3)
return false;
@@ -299,22 +365,9 @@
// 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;
- if (fSwizzler) {
- // write data to storage row, then sample using swizzler
- dstRow = fSrcRow;
- } else {
- // write data directly to dst
- dstRow = (JSAMPLE*) dst;
- }
-
+ JSAMPLE* 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);
@@ -326,13 +379,13 @@
return fDecoderMgr->returnFailure("Incomplete image data", kIncompleteInput);
}
- if (fSwizzler) {
- // use swizzler to sample row
- fSwizzler->swizzle(dst, dstRow);
- dst = SkTAddOffset<JSAMPLE>(dst, dstRowBytes);
- } else {
- dstRow = SkTAddOffset<JSAMPLE>(dstRow, dstRowBytes);
- }
+ // Convert to RGBA if necessary
+ if (JCS_CMYK == dinfo->out_color_space) {
+ convert_CMYK_to_RGBA(dstRow, dstInfo.width());
+ }
+
+ // Move to the next row
+ dstRow = SkTAddOffset<JSAMPLE>(dstRow, dstRowBytes);
}
return kSuccess;
@@ -340,30 +393,26 @@
void SkJpegCodec::initializeSwizzler(const SkImageInfo& dstInfo, const Options& options) {
SkSwizzler::SrcConfig srcConfig = SkSwizzler::kUnknown;
- 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
+ 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));
@@ -405,9 +454,8 @@
return kInvalidInput;
}
- // 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) {
+ // We will need a swizzler if we are performing a subset decode
+ if (options.fSubset) {
this->initializeSwizzler(dstInfo, options);
}
@@ -437,7 +485,12 @@
return y;
}
- if (fSwizzler) {
+ // Convert to RGBA if necessary
+ if (JCS_CMYK == fDecoderMgr->dinfo()->out_color_space) {
+ convert_CMYK_to_RGBA(dstRow, fDecoderMgr->dinfo()->output_width);
+ }
+
+ if(fSwizzler) {
// use swizzler to sample row
fSwizzler->swizzle(dst, dstRow);
dst = SkTAddOffset<JSAMPLE>(dst, rowBytes);
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