[Openicc] profile-configuration, application, CUPS, Ghostscript, Gutenprint

[Robert L Krawitz]

   From: Hal V Engel <hvengel at astound.net>
   Date: Tue, 19 Apr 2005 13:52:00 -0700

   On Tuesday 19 April 2005 05:35 am, Michael Sweet wrote:
   > Jan-Peter Homann wrote:
   snip 
   > > b) Also GhostScript has no possibility to deliver to profile for the
   > > document-colorspace to Gutenprint.
   >
   > This is correct, however IMHO Gutenprint doesn't need to know this
   > information.  It will get one of 4 colorspaces (W, RGB, K, or CMYK)
   > and can assume that W and RGB are sRGB, and K and CMYK are linear
   > CMYK which can be profiled with the transform happening in the app
   > or RIP.

   I am not sure why Gutenprint would need to make any assumptions
   about the color space of the raster image it is being handed.
   Shouldn't Gutenprint be getting the raster image in a printer model
   specific or custom device specific color space rather than a
   generic color space like sRGB?  If Gutenprint gets the document in
   the sRGB color space (the same is true for any non-model/device
   specific color space such as linear CMYK) then it must apply
   another color space transformation from sRGB to the device color
   space.

So are you advocating doing the color management in CUPS, and just
having the linearization done in Gutenprint?  In that case, we need a
16-bit path between CUPS and Gutenprint (which I gather is on the way).

   In the simplest case, which is a raster image such as a photograph,
   CUPS will be passed the image file from the app along with possibly
   some CM related arguments.  CUPS (or the filter as the case may be)
   will pull the embedded profile from the image and using other
   arguments passed by the app will use the correct printer profile
   and rendering intent to transform the image to the correct printer
   color space and pass the resulting printer specific raster image to
   Gutenprint.

   application          CUPS/GhostPrint
   gimp-print   =>  and filters            => Gutenprint => printer
   plug-in for           embedded CS to
   example              printer CS

What about the Print plugin generating raw printer-specific data?  In
that case, presumably the color management has to take place in the
plugin?

-- 
Robert Krawitz                                     <rlk at alum.mit.edu>

Tall Clubs International  --  http://www.tall.org/ or 1-888-IM-TALL-2
Member of the League for Programming Freedom -- mail lpf at uunet.uu.net
Project lead for Gimp Print   --    http://gimp-print.sourceforge.net

"Linux doesn't dictate how I work, I dictate how Linux works."
--Eric Crampton