[Radiance-general] CIE Color Conversion

[Marcus Jacobs]

Hi All

I have a question about using the existing utilities for converting a CIE 
(x,y) chromaticity to RGB for use of adjusting the default sun and sky 
colors. I have researched the following site to get some background about 
this:

http://www.fourmilab.ch/documents/specrend/

>From searching through the archive of this message board I came across a 
response by Greg to a previous question that I had for adjusting the sun 
color:

http://www.radiance-online.org/pipermail/radiance-general/2005-January/002263.html

My question is how may I convert from a CIE(x,y) chromaticity to RGB using 
on two variables as was performed for the above. The Radiance function file 
xyz_rgb.cal requires three variables (x,y and the luminosity, z). The reason 
why I am asking this is because I wish for the values that I'll employ to be 
in the physically valid range (i.e. .265074126*r + .670114631*g + 
.064811243*b = 1).

Thanks

Marcus