Quartz PDF Rendering with CMYK Page-Level Transparency Blending Color Space

Number:rdar://12796443 Date Originated:03 Dec 2012
Status:Open Resolved:
Product:Mac OS X Product Version:10.8.2
Classification:Serious Bug Reproducible:Always

If a PDF document has pages that have a page-level transparency blending color space of CMYK then all output on Mac using Quartz PDF drawing will have incorrect colors.

This affects drawing of PDFs via PDFKit, CGPDF functions, viewing in Preview and most third party apps, like e.g. Pixelmator. Adobe's apps are the only ones the display it correctly.

Interestingly the rendering behavior on iOS - including the iOS simulator on Mac - displays those PDFs correctly.

Steps to Reproduce:

Create a PDF with e.g. Adobe InDesign, have some transparent elements
Set the Page-Level Transparency Blending Color Space to CMYK
View this PDF in Preview.app

Expected Results:

Colors should look the same viewing the PDF on Mac as well as iOS.

Actual Results:

iOS (device and simulator) show correct colors, on Mac the colors look less brilliant and muddy.




If this were happening uniformly on iOS and Mac then we'd say that this might be a problem with Adobe using some weird extensions. But since the colors are correct on iOS, even in the Simulator, we think that OS X is trying to do the right thing with the blending color space, but this causes the colors to be output incorrectly.

This problem is most prevalent in the print industry because there CMYK is often as a default setting used instead of RGB. One would expect for Macs to get the colors right, being the tool of choice (even having color correction) for graphic designers worldwide.


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