Le 24/04/2010 10:38, clipka nous fit lire :

> 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.
> 

If you wanted to have actual spectrum (discret) interaction by
multiplication, you would need to distinguish between ray colour (as a
vector) and interacting colour (as a square matrix, of same dimension)

Most of the time, the matrix would be a simple diagonal one, which might
collapse to a vector, but that's a bad approach for some material (laser
pumping ruby for instance would propably have a positive column for
694.3 nm; frequency doubling material might also be interesting and
reluctant to the pure diagonal matrix).

If you go that way, you might also want to replace ior index with a
vector (and transform refraction single ray into a collection of
spectrum-discret-number ray), or even worst construct for birefringent
material. The whole domain of nonlinear optics also opens to you... you
might start applying electric field equations into material...

A ray has a vector colour, a light source too, but media & pigment would
get matrixes. And at the end of your pixel calculation, you ends up
converting your spectrum vector into the colour space of your
image-format...
Excepted for color interpolation of color map, whose curve might be a
pain to provide in RGB when a natural model exist in another colour
space, and unless you are ready to go with the matrix-replacement for
pigment & media, very little interest, IMHO.

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