[Openicc] color-policy vs. color-infrastructure

[Kai-Uwe Behrmann]

Am 08.03.05, 23:29 +1100 schrieb Graeme Gill:

> Kai-Uwe Behrmann wrote:
 
> > What things I could do on application level (CinePaint) to overcome this
> > difficulty with CIE*Lab imagery?
> > 
> > Would it
> > 1. be standard and
> > 2. help argyll/lcms
> > to add the gamut information found in the device profile to the abstract
> > profile? I am aware of many colour manipulations making the gamut
> > information useless. 
> > Other options?
> 
> This is certainly one option. Another option (at some slight additional

Would argyll and lcms provide an mechanism to take an profile as argument 
and give back eighter the gamt tag or the gamt tag added to the former 
profile?
As Marti pointed out on his list gamut tags may be not that relyable for 
usage. And I have the impression too, especially for older profiles.

> cost to performance) would be to revert to image gamut mapping (ie. source
> gamut is the gamut of the image, rather than the colorspace the image is
> defined in.) This would undoubtedly surprise many people used to the existing
> way of doing things, and has some subtle issues that should really
> be dealt with in some way.

Thats maybe an information applications can easily provide by intelligent 
scaling down an small sample image and using the ncl2 tag to store its
colours (I do in CinePaint). 
The above gamut tag seems more difficult and in the domain of CMMs.

> I can imagine additional hybrid modes too, where the source gamut is given by
> a collection of images, for instance.

Interessting. Sounds like an project aproach. This could be an profile 
containing an gamut 'gamt' tag only or the former mentioned ncl2 tag. Even 
though the device colours may not make much sense there.

I am highly interessted in this toppic. As it seems the basis to 
sucessfully use CIE*Lab as editing and transportation mode for image 
content.

> > CinePaint has the color wheels tool, storing its colour manipulation in
> > an abstract profile. This profile type works for 8 and 16 bit depths. I
> > am not shure if an device link could be used across bit depths?
> 
> I don't see any reason why not. It would be best of course if
> the abstract profile itself was Lab PCS with 16 bit precision.

Yes, thats the case.

regards
Kai-Uwe Behrmann
                                + development for color management 
                                + imaging / panoramas
                                + email: ku.b at gmx.de
                                + http://www.behrmann.name