[Openicc] CUPS Color Management under Linux gets into distros

[Kai-Uwe Behrmann]

Am 10.02.11, 15:40 +0900 schrieb Koji Otani:
> From: Till Kamppeter <till.kamppeter at gmail.com>
> Subject: Re: [Openicc] CUPS Color Management under Linux gets into distros
> Date: Wed, 09 Feb 2011 00:21:55 +0100
> Message-ID: <4D51D013.70203 at gmail.com>
>
> till.kamppeter> On 02/09/2011 12:12 AM, Chris Murphy wrote:
> till.kamppeter> > On Feb 8, 2011, at 9:33 AM, Till Kamppeter wrote:
> till.kamppeter> >> we will have some color management in a distro soon. I have added Koji
> till.kamppeter> >> Otani's Poppler-based pdftoraster filter to the CUPS package for
> till.kamppeter> >> Ubuntu Natty (release end of April, currently available as the
> till.kamppeter> >> development branch of Ubuntu) and Debian unstable. This pdftoraster
> till.kamppeter> >> filter replaces the one shipped with Ghostscript and in addition to
> till.kamppeter> >> being much faster and more reliable with complex PDFs it implements
> till.kamppeter> >> CUPS' ICC profile support as described in the documentation:
> till.kamppeter> >>
> till.kamppeter> >> http://www.cups.org/documentation.php/doc-1.4/spec-ppd.html#cupsICCProfile
> till.kamppeter> >> http://www.cups.org/documentation.php/doc-1.4/spec-raster.html#TABLE2
> till.kamppeter> >> http://www.cups.org/documentation.php/doc-1.4/raster-driver.html#COLOR
> till.kamppeter> >>
> till.kamppeter> >> Otani-san, am I correct that with this pdftoraster we have ICC-profile
> till.kamppeter> >> support for CUPS Raster drivers as described in the CUPS doc? How do I
> till.kamppeter> >> supply a rendering intent? Are there any additional non-PPD options to
> till.kamppeter> >> supply to print jobs?
> till.kamppeter> >> Color management experts from OpenICC and driver developers, please
> till.kamppeter> >> test this feature and report your experience here. You could ship ICC
> till.kamppeter> >> profiles for installation in /usr/share/cups/profile/ to improve your
> till.kamppeter> >> printer's output quality.
> till.kamppeter> >> Color management experts from OpenICC, WDYT about this color
> till.kamppeter> >> management effort? Is this already a step forward? Is it at least the
> till.kamppeter> >> correct effort for consumer-level printing? What needs to be added to
> till.kamppeter> >> support pro and prosumer printing?
> till.kamppeter> >
> till.kamppeter> > Seems to me any pdftoraster filter needs to honor the PDF contents,
> till.kamppeter> > not do extra things on its own. Or we run into trouble.
> till.kamppeter> > So if this pdftoraster honors ICCBased without substitution, that's
> till.kamppeter> > good. If its implementation of CUPS ICC profile support means that it
> till.kamppeter> > uses externally referenced profiles as the destination profile, that's
> till.kamppeter> > fine *UNLESS* the PDF print spool file contains an OutputIntent in
> till.kamppeter> > which case that needs to be used. So does pdftoraster support
> till.kamppeter> > OutputIntent?
> till.kamppeter>
> till.kamppeter> I do not know. Otani-san, can you answer Chris' question?
> till.kamppeter>
> till.kamppeter>    Till
> till.kamppeter>
>
> pdftoraster doesn't support OutputIntent now,
> INTENT_RELATIVE_COLORIMETRIC is hardcoded.

Please note, the PDF OutputIntent is a literal ICC profile. This is 
confusing as its is different from the ICC term "rendering intent", which 
describes the prefered gamut mapping between two ICC profiles.

citation from Leonard Rosenthol, Mon Feb 7 2010 at 16:51:42 PST:
> OutputIntent doesn't convert anything.  It serves two purposes in PDF/X,
> PDF/A and PDF/E - and NO PURPOSE  in a standard PDF (since the spec says 
> it should be ignored).   The two uses are:
> - Destination Profile for the target device (should you need to retarget)
> - Source Profile for any DeviceXXX colored object(s)

Let me reformulate the question.
Will poppler colour convert the PDF to a destination 
profile which is embedded in a PDF/X (/A, /E) as "OutputIntent" ?

> Should it take OutputIntent from cupsRebderingIntent Page Device
> Attributes in PPD ?
>
> As Mr. Engel wrote, poppler doesn't support rendering intent in PDF content,
> INTENT_RELATIVE_COLORIMETRIC is hardcoded in it.
> This is because that too many changes on poppler were needed
> when I created patch for poppler.

Thanks for clearifying about the current state for the rendering intent in 
poppler.

kind regards
Kai-Uwe Behrmann
-- 
developing for colour management 
www.behrmann.name + www.oyranos.org