Re: [Algorithms] RGB to XYZ conversion

[<chr...@pl...>]

Dan Glastonbury wrote:
> Dear colour space experts
>  What matrix should I being using to convert RGB values to CIE XYZ?
> Christer Ericson (http://realtimecollisiondetection.net/blog/?p=15)
> gives the following matrix:
>
>   M = [0.497,0.339,0.164]
>       [0.256,0.678,0.066]
>       [0.023,0.113,0.864]
>
> to be used in [X Y Z] = [R G B]*M and I assume this comes from Greg
> Ward's paper.  Charles Poynton's ColorFAQ and wikipedia's article on
> CIE 1931 give different formulations for the conversion.

Good question Dan, and I for one don't know the answer. I asked myself
the same question when I wrote that blog post and first worked out the
code. Everywhere you look, there's another subtly different matrix
given. As we didn't end up using any logluv encodings, I never tried
to find out what's the "correct" matrix. As you correctly assumed, I
just used the values given in Greg Ward's paper for the blog post.


Christer Ericson, Director of Tools and Technology
Sony Computer Entertainment, Santa Monica
http://realtimecollisiondetection.net/blog/