Ive schrieb:

> But again, all this is not relevant when using s(c)RGB as a working 
> color space and there has something like the Bradford chromatic adaption 
> to be applied for given xyY values to make e.g. POV-Ray calculate with 
> "good" RGB values.

I don't get it. On one hand, you are saying that reference white does 
not matter for sRGB as a working color space (unless I misunderstand 
you, which I guess I do), on the other hand yo're saying some adaption 
/must/ be applied?

I'm pretty sure somehow that the /spectrum/ of the whitepoint should 
matter for such things as dispersion, but where and why adaption come 
into play still eludes me.

Let me think aloud for a moment to try to sort this out, and kick me 
where I'm wrong:

So the starting point is the /tristimulus/, which (basically) models how 
strongly the three different color receptors ("cones") in the human eye 
react to different wavelengths. (To my knowledge we can count the "rod" 
receptors out, probably because they only contribute in dim conditions, 
right? Otherwise we should be able to distinguish four different 
primaries, as the rods' spetral response is yet again different than the 
cones'.)

Experiments were conducted to measure this per-wavelength response (a 
bit indirectly) in a manner that, to my understanding, only yielded 
/relative/ results: Conclusion could be drawn how much stronger a 
particular cone type is stimulated by wavelength A compared to some 
other wavelength B, but there was no way to infer how much stronger a 
particular wavelength stimulated cone type A as compared to cone type B. 
Thus, the immediate conclusions drawn from these experiments left open 
the question what "white" is (which comes as no surprise, given that it 
depends on the viewing conditions, i.e. the eye's "calibration").

However, I'm a bit worried at this point already: I guess the 
wavelengths to test were generated from a "white" light source by means 
of a prism; did they actually measure the physical light intensity of 
the light source at that particular wavelength, to compensate for any 
nonlinearities in intensity in their results? Or is there a hidden 
"whitepoint" in the original data already, due to the light source used?


Duh - I haven't even really /started/ thinking about the problem of 
whitepoint, and it gets in my way already...

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