LibGfx: Correctly determine when to invert CMYK

We should invert CMYK data only if color space is JCS_CMYK and either
there is no Adobe marker, or the Adobe transform is 0. Transform 2
indicates YCCK data, which we should not invert.

Libraries/LibGfx/ImageFormats/JPEGLoader.cpp

@@ -148,7 +148,10 @@ ErrorOr<void> JPEGLoadingContext::decode()
 
         // Photoshop writes inverted CMYK data (i.e. Photoshop's 0 should be 255). We convert this
         // to expected values.
-        if (cinfo.saw_Adobe_marker) {
+        bool should_invert_cmyk = cinfo.jpeg_color_space == JCS_CMYK
+            && (!cinfo.saw_Adobe_marker || cinfo.Adobe_transform == 0);
+
+        if (should_invert_cmyk) {
             for (int i = 0; i < cmyk_bitmap->size().height(); ++i) {
                 auto* line = cmyk_bitmap->scanline(i);
 

Tests/LibGfx/TestImageDecoder.cpp

@@ -323,6 +323,42 @@ TEST_CASE(test_jpeg_ycck)
     }
 }
 
+TEST_CASE(test_jpeg_cmyk_no_adobe_marker)
+{
+    auto file = TRY_OR_FAIL(Core::MappedFile::map(TEST_INPUT("jpg/cmyk-no-adobe-marker.jpg"sv)));
+    EXPECT(Gfx::JPEGImageDecoderPlugin::sniff(file->bytes()));
+    auto plugin_decoder = TRY_OR_FAIL(Gfx::JPEGImageDecoderPlugin::create(file->bytes()));
+    TRY_OR_FAIL(expect_single_frame_of_size(*plugin_decoder, { 10, 10 }));
+
+    EXPECT_EQ(plugin_decoder->frame(0).value().image->get_pixel(8, 1), Gfx::Color(44, 184, 97));
+    EXPECT_EQ(plugin_decoder->frame(0).value().image->get_pixel(1, 8), Gfx::Color(184, 44, 97));
+    EXPECT_EQ(plugin_decoder->frame(0).value().image->get_pixel(9, 9), Gfx::Color(24, 24, 194));
+}
+
+TEST_CASE(test_jpeg_cmyk_adobe_transform_0)
+{
+    auto file = TRY_OR_FAIL(Core::MappedFile::map(TEST_INPUT("jpg/cmyk-adobe-transform-0.jpg"sv)));
+    EXPECT(Gfx::JPEGImageDecoderPlugin::sniff(file->bytes()));
+    auto plugin_decoder = TRY_OR_FAIL(Gfx::JPEGImageDecoderPlugin::create(file->bytes()));
+    TRY_OR_FAIL(expect_single_frame_of_size(*plugin_decoder, { 10, 10 }));
+
+    EXPECT_EQ(plugin_decoder->frame(0).value().image->get_pixel(8, 1), Gfx::Color(44, 184, 97));
+    EXPECT_EQ(plugin_decoder->frame(0).value().image->get_pixel(1, 8), Gfx::Color(184, 44, 97));
+    EXPECT_EQ(plugin_decoder->frame(0).value().image->get_pixel(9, 9), Gfx::Color(24, 24, 194));
+}
+
+TEST_CASE(test_jpeg_ycck_adobe_transform_2)
+{
+    auto file = TRY_OR_FAIL(Core::MappedFile::map(TEST_INPUT("jpg/ycck-adobe-transform-2.jpg"sv)));
+    EXPECT(Gfx::JPEGImageDecoderPlugin::sniff(file->bytes()));
+    auto plugin_decoder = TRY_OR_FAIL(Gfx::JPEGImageDecoderPlugin::create(file->bytes()));
+    TRY_OR_FAIL(expect_single_frame_of_size(*plugin_decoder, { 10, 10 }));
+
+    EXPECT_EQ(plugin_decoder->frame(0).value().image->get_pixel(8, 1), Gfx::Color(197, 27, 134));
+    EXPECT_EQ(plugin_decoder->frame(0).value().image->get_pixel(1, 8), Gfx::Color(24, 199, 134));
+    EXPECT_EQ(plugin_decoder->frame(0).value().image->get_pixel(9, 9), Gfx::Color(227, 224, 19));
+}
+
 TEST_CASE(test_jpeg_sof2_spectral_selection)
 {
     auto file = TRY_OR_FAIL(Core::MappedFile::map(TEST_INPUT("jpg/spectral_selection.jpg"sv)));