[argyllcms] Re: Measuring a colorcheker on screen

Am 25.01.08, 16:29 +1100 schrieb Graeme Gill:
> Kai-Uwe Behrmann wrote:
> > ICC(v4.2) D 7.2 clears about display handling as a emmisive device:
> > 
> > "Thus, for practical reasons, it is important that the monitor profiles
> > be designed to display paper white at full-drive monitor white (R = G = B
> > = 255 on a typical 24-bit display). Similarly, there is an expectation
> > that R = G = B = 0 corresponds to "black" and will be reproduced by the
> > minimum reflectance of the output medium. These user expectations are
> > based on common practice and convenience and lie outside of strict
> > colorimetry and colour-appearance considerations."
> 
> Right, but the intent used to link the input to the display profile
> will have an effect as well. If you link an idealized RGB input profile
> (say sRGB) with an actual display profile with a non-zero black point
> using relative colorimetric intent (or a good perceptual intent etc.),
> then asking for XYZ = 0,0,0 is outside the gamut of the display
> device, and it will clip to its minimum possible black, satisfying the
> above requirements. ie., the above guidance does not imply that
> a display profile must have a black point of 0.

Things are mixed easily.
My monitor test profiles, including the old ones from Argyll, had eigther 
no measurements included or no blackpoint tag. I have to fix ICC Examin as 
its current monitor measurement scaling is only a special case.
 
Thanks,
Kai-Uwe Behrmann
--
developing for colour management 
www.behrmann.name + www.oyranos.org

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