[Openicc] questions about Compiz

[Kai-Uwe Behrmann]

Am 30.01.11, 15:38 -0800 schrieb Hal V. Engel:
> On Sunday, January 30, 2011 01:17:45 pm Jan-Peter Homann wrote:

I think Hal has already andwered most questions. Just let me add some 
insight about compiz ICC colour server, the plugin called CompICC.

>> Wich kind of color transformations are supported from Compiz:
>> - RGB 2 RGB
>> - CMYK 2 RGB

Cmyk to Rgb is not coverd as I know of no way to supply n channel data to 
Xorg.

>> - RGB 2 CMYK 2 RGB
>
> Compiz assumes that everything handed to it is device RGB and it does not know
> how to do color space transforms at least in the sense we use that terminology
> and in it's default state knows nothing about CM.
>
> In order to make Compiz handle color transformations OpenICC had a GSoC
> project to write a Compiz plug in named CompICC that converts application
> supplied display output (windows, borders, menus, images...) which is always
> in RGB format (because the app assumes it is talking to the composting engine)
> and transforms this output to device RGB for what ever device that output will
> be displayed on and hands this to Compiz to compost onto the display.

Exactly. CompICC takes the window bitmap and converts all regions (or 
areas/pixels), which are not opted out, to the actual monitors device 
profiles. CompICC assumes allways sRGB as source colour space.

Most colour management settings fom Oyranos can be applies to the CompICC
colour transforms. This includes rendering intent selection, black point 
compensation, out of gamut marking and proofing. This is technically 
possible, and demonstrated in the actual development version. However its 
unclear if that might be useful.

>> Would it be able to implent a rendering to fileout
>> - RGB 2 CMYK
>> - CMYK 2 CMYK
>> (Fast rendering of Bitmaps for Printout)
>
> This is outside of the scope of Compiz since it part of the display pipe 
> line.

Agreed.

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