[PDFBOX-2681] Colors inaccurate rastered CMYK source w/ gradient + photo

• Type: Bug
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: 2.0.0
• Component/s: Rendering
• Environment: Tested on OS X 10.10, Java 1.6 / 1.8
• Assignee: Unassigned
• Reporter: Jon Wu
• Created: 12/Feb/15 02:27
• Updated: 20/Feb/15 12:04

Description

In the attached gradient-test-photo.pdf, there's a photo with a gradient on top of it. The colors in the gradient are CMYK. When rasterizing this test file with PDFBox 2.0.0 SNAPSHOT 20150209, the resulting image's gradient is different from the original and the colors of the photo under the gradient look significantly different vs the display in Adobe tools like Illustrator or other compliant PDF readers.

Issues:

• Color hue is wrong. Is this a CMYK to RGB issue?
• Opacity of gradient is wrong and much different. The jpg from Illustrator shows much more of the photo without a gradient over it.

Without a photo, there's still a difference, but it's much harder to see. Example in gradient-test.pdf where the same gradient is drawn over a grey rectangle.

If I convert the PDF to RGB in Illustrator first and rasterize the RGB PDF with PDFBox, the result is nearly identical between Illustrator and PDFBox so this seems like a CMYK conversion issue in both the general color conversion and maybe how the gradient is calculated.