[poppler] lcms usage in poppler

Thomas Freitag thomas.freitag.bbr at gmail.com
Sun Aug 4 05:35:21 PDT 2013

Hello Leonard!

There is at least one point I'm missing:
1. The PDF spec says that the default rendering intent is 
2. The explanation in the 070-072_ReadMe_Ghent_Output_Patch.pdf says 
that the crosses should be rendered with Perceptual rendering
But what inside the patch tests says that not the default, but the 
Preceptual rendering intent should be used? I haven't found any 
rendering intent parameters in the patches. Does GTS_PDFX as subtype 
and/or the ICC profile ine OutputIntents directory forces this?

Thanks for any help,

Am 04.08.2013 13:30, schrieb Leonard Rosenthol:
> The files from the GWG are PDF/X compliant.  That means that to correctly
> display them you need to follow the rules for PDF/X - NOT JUST standard
> PDF.   So until you implement all of the PDF/X "conforming reader"
> requirements (and only for PDF/X files, of course), you will never render
> them 100% correctly.
> Leonard
> On 8/4/13 6:34 AM, "Thomas Freitag" <thomas.freitag.bbr at gmail.com> wrote:
>> Am 02.08.2013 19:50, schrieb Albert Astals Cid:
>>> El Divendres, 2 d'agost de 2013, a les 17:05:38, Thomas Freitag va
>>> escriure:
>>>> Hi Folks!
>>>> Can anybody tell me how I can really test the lcms integration in
>>>> poppler? I thought it should work, but now I'm no more sure. Reason for
>>>> the change of my mind is that I tried to implement the usage of
>>>> OutputIntents.
>>> Is your implementation similar to the one i did 2 years ago?
>>> https://bugs.freedesktop.org/show_bug.cgi?id=34053
>> Thanks for the hint, Albert. In the meantime I already encountered, that
>> creating the transformation with INTENT_PERCEPTUAL instead of
>> INTENT_RELATIVE_COLORIMETRIC works fine with the GWG tests (This time I
>> attach only one result, but the two other are also okay). Now I'd read
>> the bug comments, but I did't find any intent entries in the PDF. BUT:
>> as far as I understand the PDF spec, the settings in output profile
>> should be used if there are no intent entries, and indeed, the profile
>> pointed by the OutputIntents dictionary says:
>> icc:RenderingIntent               : Perceptual
>> Should I try fix it in that way and and attach a patch to bug 34053?
>> Cheers,
>> Thomas
>>> I could not find either why it was not working.
>>> Maybe you can mix your idea and my idea and get something that works?
>>> Cheers,
>>>     Albert
>>>> Motivation is the GWG, patch series 7 (07_OutputIntent),
>>>> but the result of my first tests is not really satisfying, s.
>>>> attachments. Of course it's a little bit better than without my
>>>> implementation, see i.e. the shading cross. But it's not like it should
>>>> be. So I'm wondering now if the reason for it
>>>> 1. is my wrong implementation (but in the debugger I saw that the lcms
>>>> transformation is called) or
>>>> 2. is the integration of lcms in poppler, at least in the CMYK area (I
>>>> need to test it there, because the profiles in the PDF are CMYK
>>>> profiles) or
>>>> 3. is lcms with this kind of profiles (the profiles are REALLY small
>>>> for
>>>> CMYK profiles, normally I see CMYK profiles with a size of at least 512
>>>> kByte).
>>>> Cheers,
>>>> Thomas
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