[Openicc] CUPS Color Management under Linux gets into distros

[Hal V. Engel]

On Tuesday, February 08, 2011 02:20:21 PM Till Kamppeter wrote:
> On 02/08/2011 10:14 PM, Hal V. Engel wrote:
> > This page is not current as it has things like links to patches for
> > poppler-0.11.x which I think add CM support similar to what is in
> > poppler-0.12.0 and later. Most recent release is 0.16.2 and most distros
> > will have version 0.14.4 or 0.14.5 as the stable version so no patches
> > are required for most users unless they are running very old software.
> > 
> > 
> > It has a section on GhostScript 8.64 when the current version is 9.0
> > although 9.0 is not yet included in most distros as a stable version.
> 
> I will remove these old patches. I have always added new stuff to the
> page but not removed the old stuff.
> 
> > But it seems to me that any testing should be done using the latest
> > version of GhostScript since this will likely be commonly used by the
> > time the PDF printing work flow is in wide use. Also I noticed that
> > Ghostscript appears to create a pdftoraster filter. To test this I just
> > installed GhostScript-9.0 on my system (Gentoo so this is built from
> > source) and it does create a pdftoraster as well as pstopxl and
> > pstoraster filters. Interestingly the ebuild also installed
> > poppler-data-0.4.,4 as a package that GhostScript is dependant on.
> > Perhaps we should also test the GS V9 version of this as well since it
> > may actually have better CM support than the poppler based filter (IE.
> > maybe it supports rendering intent and/or uses the PDF OutputIntents to
> > get the output profile for example).
> 
> Ghostscript's pdftoraster I used for a long time in Ubuntu. Without
> color management as this got only added with 9.00. Currently, I have
> packaged 9.01 (SVN snapshot) for Ubuntu Natty, but the pdftoraster
> (cups/pdftoraster.c) and Ghostscript's "cups" output device
> (cups/gdevcups.c) are not yet prepared for CM. If you (or someone on the
> list) could help here it would be great.
> 
> Due to Poppler being faster and more reliable as a PDF interpreter and
> due to Koji Otani having added CM support to his Poppler-based
> pdftoraster I have switched to this one in Ubuntu Natty. To avoid file
> name conflicts I have renamed it to pdftoraster-poppler and set the cost
> factor for it in the .convs files lower than the cost factor of
> Ghostscript's pdftoraster. This way both are installed in Ubuntu and the
> user/admin can switch to the other by changing the cost factors.
> 
> Any help to get the best possible printing color management solution for
> Ubuntu/Debian is appreciated.
> 
>     Till

While writing up the rendering intent bug report for poppler I looked at the 
code in poppler that creates the transforms and noticed after also looking at 
the lcms header that it always outputs 8 bits per channel since this is also 
hard coded in poppler.  So this is another thing that needs to be fixed since 
it should allow for the calling app to decide what bit depth to use for 
output.  For Gutenprint we will definitely want 16 bit per channel output for 
example.  Again we can live with 8 bit/channel output for initial testing but 
this does need to get fixed.  I will enter a bug report.  This sould not be a 
difficult fix for the poppler folks since all they have to do is expose the 
functionality.  But it is likely to make things in the printing work flow a 
little more complex.  See https://bugs.freedesktop.org/show_bug.cgi?id=34055

I will take a look at the GS stuff but I don't know how much progress I can 
make with this since I will be looking at code that I am not at all familiar 
with.

Hal
Hal
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