"Tony[B]" wrote:
> 
> > I have reviewed the CIE formula, and come to the conclusion, that it is
> > better to convert back from xyz to XYZ values and use them as RGB. That
> > is done by multiplying x and z by Y divided by y: X = x * (Y/y), Z = z
> > *(Y/y). Y we already have as the luminance.
> 
> Actually, right now, I'm dividing each chromaticity value by the largest
> value of the triplet, and using luminance as diffuse. It works as expected,
> most of the time. Some colors are a bit dark.

That brings the question to mind: how do you know what to expect?

Anyway, I have tried your technique, and compared it to my suggestion,
and we get very similar colours. There is however a subtle difference in
the shading of the spheres, that I used for my test. I think that is
because you change the ratio between the amount of diffuse and ambient
light, that is reflected from the surface, and that changes the
difference between highlights and shadows along with the apparent
colour. I prefer to control the colour with the rgb-values, and leave
ambient and diffuse alone.

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