[Poppler-bugs] [Bug 34053] Poppler ignores rendering intents and always uses INTENT_RELATIVE_COLORIMETRIC

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=34053

--- Comment #9 from Hal Engel <hvengel at astound.net> 2011-02-09 17:49:45 PST ---
I applied the patch and added some debugging statements so that I could see
what it was doing and it is picking up the RI values from the PDF file and it
appears to be passing the correct RI values into the cmsCreateTransform() call.
 But I am also seeing that it does not make a difference in the rendered
results when I run qt4/demos/poppler_qt4viewer. That is I am seeing differences
in places where there should be none or at most only a small difference (IE.
#34 - big difference - and #35 - very small difference) and not seeing
differences where it should exist in the other tests in the PDF (IE. #36, #37
and #38) where RI should affect the output.

I don't know why this is happening but there are clearly issues with how things
are rendered even without the rendering intent issue (#34 for example) and
rendering intent is clearly not having an effect on how things are rendered.   
Since I am looking at this on a monitor it is possible that the gamut of the
output profile (this would be sRGB in this case since the viewer does not know
how to get the ICC_PROFILE atom and setup a correct transform) is large enough
that for these objects relative colormetric would give the same or nearly the
same results as a perceptual transform.  That is if the gamut of the output
device is large enough the two transforms may not result in different output. 
This is intended for testing with a printer device profile which will have a
significantly smaller gamut and this will cause relative colormetric to clip
some colors and perceptual to compress the output color to fit in the small
space which would make the affect of different RIs more visible.

I will ask others on the OpenICC list to have a look to see if someone can spot
what it going on.

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