[cairo] RFC the idea of n-plane color support

[Kai-Uwe Behrmann]

Am 03.11.04, 11:59 -0500 schrieb Carl Worth:

> On Sun, 31 Oct 2004 11:05:44 +0100 (CET), Kai-Uwe Behrmann wrote:
> > How passes an ICC profile through Cairo to an final PDF output or to glitz
> > for monitor correction? Physical devices are allways different.
> > As Microsoft plans to overcome GDI, they will go steps further to
> > support 8/16-bit (sRGB,scRGB,CMYK,n-color) colorspaces in WCS.
>
> The concept in cairo is that the user input color is all specified in
> sRGB. Currently implemented backends are 8-bit per channel, but the API
> is floating-point so future 16-bit or floating-point backends are
> possible.

These are interessting news, thanks.

> Since cairo provides only an sRGB API, it just assumes that the monitor
> is already calibrated to sRGB. So the calibration issue is external to
> cairo.

This is the ideal world, which only works with selfcalibrating devices.
Most people lack of such expensive devices. Colour measurement equipment
becomes cheaper. This makes colour management interessting.

Passing of an source profile, think of it like an attchment, could be
sufficient for RGB images. But it simply moves the colour
management from cairo to the backends.

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