Re: Adding printer profiling support

[Milan Knížek <knizek confy volny cz>]

Pascal de Bruijn píše v Čt 18. 02. 2010 v 18:57 +0100:
> On Thu, Feb 18, 2010 at 5:50 AM, Pedro Côrte-Real <pedro pedrocr net> wrote:
> > - Selecting the source profile would be nice too (defaulting to sRGB)
> > and possibly allowing the user to later generate the same profile with
> > another profile (e.g. AdobeRGB) as source might be useful.
> 
> Huh? printer profiles usually use LAB as Profile Connection Space,
> this has nothing to do with sRGB/AdobeRGB.
> 
> The pipeline:
> Image (in sRGB) -> sRGB profile -> XYZ (-> LAB) -> printer profile ->
> printer native RGB/CMYK -> hpijs/gutenprint

It looks like Pedro was referring to -S option of colprof:

Argyllcms docs quote [1]:
-- 
Where the resulting profile will be used conventionally (ie. using
collink -s, or cctiff or most other "dumb" CMMs) it is important to
specify that gamut mapping should be computed for the output (B2A)
perceptual and saturation tables. This is done by specifying a device
profile as the parameter to the colprof -S flag. When you intend to
create a "general use" profile, it can be a good technique to specify
the source gamut as the opposite type of profile to that being created,
i.e. if a printer profile is being created, specify a display profile
(e.g. sRGB) as the source gamut. If a display profile is being created,
then specify a printer profile as the source (e.g. SWOP). 
-- 

Argyllcms docs quote [2]:
... [Note that Shaper/Matrix profiles are always Colorimetric intent,
since there is only a single transformation, and it does not have the
necessary flexibility to accommodate gamut mapping.]

... So to construct the perceptual and saturation intent mapping tables,
a source profile or source gamut needs to be specified, so that a gamut
mapping can be constructed.
-- 

[2] http://www.argyllcms.com/doc/Scenarios.html#PP5
[1] http://www.argyllcms.com/doc/iccgamutmapping.html

I do not have much experience on this topic...

regards,

Milan Knizek
knizek (dot) confy (at) volny (dot) cz
http://www.milan-knizek.net - About linux and photography (Czech
language only)