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LibPDF+LibGfx: Don't invert CMYK channels in JPEG data in PDFs

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This is a hack: Ideally we'd have a CMYK Bitmap pixel format,
and we'd convert to rgb at blit time. Then we could also apply color
profiles (which for CMYK images are CMYK-based).

Also, the colors for our CMYK->RGB conversion are off for PDFs,
and we have distinct codepaths for this in Gfx::Color (for paths)
and JPEGs. So when we fix that, we'll have to fix it in two places.

But this doesn't require a lot of code and it's a huge visual
progression, so let's go with it for now.
This commit is contained in:
Nico Weber 2023-11-15 12:58:06 -05:00 • committed by Sam Atkins
parent bd7ae7f91e
commit bfe27228a3
3 changed files with 26 additions and 6 deletions
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18
Userland/Libraries/LibGfx/ImageFormats/JPEGLoader.cpp
View file

@ -416,15 +416,16 @@ enum class ColorTransform {
};
struct JPEGLoadingContext {
JPEGLoadingContext(JPEGStream jpeg_stream)
JPEGLoadingContext(JPEGStream jpeg_stream, JPEGDecoderOptions options)
: stream(move(jpeg_stream))
, options(options)
{
}
static ErrorOr<NonnullOwnPtr<JPEGLoadingContext>> create(NonnullOwnPtr<Stream> stream)
static ErrorOr<NonnullOwnPtr<JPEGLoadingContext>> create(NonnullOwnPtr<Stream> stream, JPEGDecoderOptions options)
{
auto jpeg_stream = TRY(JPEGStream::create(move(stream)));
return make<JPEGLoadingContext>(move(jpeg_stream));
return make<JPEGLoadingContext>(move(jpeg_stream), options);
}
enum State {
@ -453,6 +454,7 @@ struct JPEGLoadingContext {
Array<i16, 4> previous_dc_values {};
MacroblockMeta mblock_meta;
JPEGStream stream;
JPEGDecoderOptions options;
Optional<ColorTransform> color_transform {};
@ -1640,7 +1642,8 @@ static void invert_colors_for_adobe_images(JPEGLoadingContext const& context, Ve
static void cmyk_to_rgb(JPEGLoadingContext const& context, Vector<Macroblock>& macroblocks)
{
invert_colors_for_adobe_images(context, macroblocks);
if (context.options.cmyk == JPEGDecoderOptions::CMYK::Normal)
invert_colors_for_adobe_images(context, macroblocks);
for (u32 vcursor = 0; vcursor < context.mblock_meta.vcount; vcursor += context.vsample_factor) {
for (u32 hcursor = 0; hcursor < context.mblock_meta.hcount; hcursor += context.hsample_factor) {
@ -1944,9 +1947,14 @@ bool JPEGImageDecoderPlugin::sniff(ReadonlyBytes data)
}
ErrorOr<NonnullOwnPtr<ImageDecoderPlugin>> JPEGImageDecoderPlugin::create(ReadonlyBytes data)
{
return create_with_options(data, {});
}
ErrorOr<NonnullOwnPtr<ImageDecoderPlugin>> JPEGImageDecoderPlugin::create_with_options(ReadonlyBytes data, JPEGDecoderOptions options)
{
auto stream = TRY(try_make<FixedMemoryStream>(data));
auto context = TRY(JPEGLoadingContext::create(move(stream)));
auto context = TRY(JPEGLoadingContext::create(move(stream), options));
auto plugin = TRY(adopt_nonnull_own_or_enomem(new (nothrow) JPEGImageDecoderPlugin(move(context))));
TRY(decode_header(*plugin->m_context));
return plugin;

12
Userland/Libraries/LibGfx/ImageFormats/JPEGLoader.h
View file

@ -16,10 +16,22 @@ struct JPEGLoadingContext;
// For the specification, see: https://www.w3.org/Graphics/JPEG/itu-t81.pdf
struct JPEGDecoderOptions {
enum class CMYK {
// For standalone jpeg files.
Normal,
// For jpeg data embedded in PDF files.
PDF,
};
CMYK cmyk { CMYK::Normal };
};
class JPEGImageDecoderPlugin : public ImageDecoderPlugin {
public:
static bool sniff(ReadonlyBytes);
static ErrorOr<NonnullOwnPtr<ImageDecoderPlugin>> create(ReadonlyBytes);
static ErrorOr<NonnullOwnPtr<ImageDecoderPlugin>> create_with_options(ReadonlyBytes, JPEGDecoderOptions = {});
virtual ~JPEGImageDecoderPlugin() override;
virtual IntSize size() override;

2
Userland/Libraries/LibPDF/Filter.cpp
View file

@ -271,7 +271,7 @@ PDFErrorOr<ByteBuffer> Filter::decode_jbig2(ReadonlyBytes)
PDFErrorOr<ByteBuffer> Filter::decode_dct(ReadonlyBytes bytes)
{
if (Gfx::JPEGImageDecoderPlugin::sniff({ bytes.data(), bytes.size() })) {
auto decoder = TRY(Gfx::JPEGImageDecoderPlugin::create({ bytes.data(), bytes.size() }));
auto decoder = TRY(Gfx::JPEGImageDecoderPlugin::create_with_options({ bytes.data(), bytes.size() }, { .cmyk = Gfx::JPEGDecoderOptions::CMYK::PDF }));
auto frame = TRY(decoder->frame(0));
return TRY(frame.image->serialize_to_byte_buffer());
}