Am 24.04.2010 05:57, schrieb Ray Gardener:
> clipka wrote:
>> Am 15.04.2010 11:07, schrieb Ray Gardener:
>>
>>> The problem turned out to be the color model. In RGB, it's hard or
>>> perhaps intractable; in CIE it's easy because the color units are more
>>> directly mapped to actual radiation wavelengths which the
>>> scattering/absorption equations prefer, and tonemapping to handle eye
>>> dark/light adaptation is easy too.
>>
>> Is that "CIE" as in "CIE RGB", "CIE XYZ", or "CIE L*a*b*"?
>
> CIE XYZ.

Hm... I don't see how that would more directly map to wavelengths - 
except maybe that the CIE tristimulus tables are closely related to the 
XYZ model, but that's a rather arbitrary "coincidence", and with some 
simple math you can make corresponding tables for any RGB model you choose.

Of course operating in an RGB model does require you to allow for 
negative color components to get the same gamut as XYZ.

Then again, it may be that the XYZ model just happens to be more 
forgiving when it comes to such things as multiplying two colors - which 
in theory will /never/ work out in /any/ color model that uses the 
standard three-component color vector approach.


As for tonemapping, shouldn't that just be a change in brightness? AFAIK 
the eye's brightness adaptation is a pretty linear thing.

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