[poppler] lcms usage in poppler

Thomas Freitag thomas.freitag.bbr at gmail.com
Mon Aug 5 01:23:20 PDT 2013

Thanks, Leonard!

That clearifies it, and also makes the remarks of Olaf clearer: the GWG 
patches use the "ri" stream operator which I missed just looking into 
the PDF objects, and of course the tests set it to "Perceptual", but 
this was only implemented in the patch of Albert for bug 34053 (sorry, 
Albert, I should have taken a deeper look into that patch first).
I think, I'm now able to create a correct patch to render the GWG files 
correctly, and I'll have also a look into the altona file.

@Albert: Should we now continue the discussion now on bug 34053? I 
think, I've now all informations necessary, and what You're missing in 
Your patch at that bug is the usage of OutputIntents and probably that 
You'll see only differences if You render the altona file in CMYK mode!


Am 04.08.2013 15:00, schrieb Leonard Rosenthol:
> On 8/4/13 8:35 AM, "Thomas Freitag" <thomas.freitag.bbr at gmail.com> wrote:
>> 1. The PDF spec says that the default rendering intent is
>> RelativeColormetric
> Correct.
>> 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.
> I haven't looked at the patches, so I can't be certain.
> However, I can say that the RI can be changed from the default in one of
> three ways.
> 1 - the 'ri' operator in the content stream
> 2 - the 'RI' key in an ExtGState dictionary (which is set with the 'gs'
> operator)
> 3 - the 'Intent' key on a specific image XObject.
> Make sure you've looked at all three.
>> Does GTS_PDFX as subtype and/or the ICC profile ine OutputIntents
>> directory forces this?
> NO!   However, when acting as a PDF/X compliant viewer, you WOULD use that
> profile as the source and/or destination profile for rendering instead of
> some other "working space".
> Leonard

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