[Poppler-bugs] [Bug 14526] Poppler incorrectly renders CMYK colors

[bugzilla-daemon at freedesktop.org]

http://bugs.freedesktop.org/show_bug.cgi?id=14526





--- Comment #5 from Troy Henderson <thenders at gmail.com>  2008-02-17 14:43:16 PST ---
Well, the problem seems to be that neither Adobe nor Poppler is rendering this
particular PDF correctly (even though their renderings are essentially the
same).  It seems that Adobe isn't following its own PDF Reference at

http://www.adobe.com/devnet/pdf/pdfs/PDFReference.pdf

since its rendering (for this color) is bad.  Section 6.2.4 on page 380 of this
document shows the conversion formula for which the patch that I provided
implements.

So it seems that something is not consistent here.  Is Adobe's formula wrong? 
It seems to be working properly for the patch I provided and the PDF I
provided.  Is Adobe incorrectly implementing its own formula?  Is Adobe even
using this formula?  Is Adobe incorrectly implementing a formula similar to
GhostScript?  If this incorrect implementation is in fact what is happening, is
Poppler making the same mistake as Adobe in its implementation (since their
results seem to be virtually identical)?  Is there something wrong with my
provided PDF?  It was generated from preview.eps which was generated using
MetaPost, and it renders as expected in GSView and Evince (which both use
GhostScript).  It was converted to PDF using GhostScript (namely `epstopdf'). 
Has this conversion changed the colors?

Thoughts?


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