[cairo] Spot colors (and CMYK)

[Kai-Uwe Behrmann]

Am 20.01.10, 12:15 -0800 schrieb Bill Spitzak:
> What is needed is "this is a spot color with this id" along with "here
> is the sRGB alternative". Devices that do not understand spot colors can
> use the alternative. Drivers that do recognize the spot color can
> instead allocate another channel (along with RGB) to accumulate it and
> set RGB to zero. After compositing is done they convert the remaining
> RGB into ink levels.
>
> C,M,Y,K can themselves be spot colors, perhaps with predefined ids.

(Perhaps I simply dont have yet your point with that ID.)
Why this ID? What is the advantage in doing this ID style table 
referencing compared to say a structure containing a direct reference to a 
rich(spot) colour entry? The actual editing space fallback is good as last 
resort, yes. Is the necessary lookup in tables typical for Cairo usage?

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