color calculations in mgfilt

Hi,

mgfilt is not really part of the core Radiance package, but typically
used with Radiance. So I hope this is not entirely off-topic.

I have been using mgfilt from time to time as a convenient tool for
getting color coordinates from measured reflection spectra. However some
results appeared a bit strange, and thus I did a comparision with what I
get from mgfilt and the results of using the CIE formulae with rcalc
instead. To make it short, the results I got from mgfilt were quite off,
and I am wondering wether I did something wrong or the accuracy
implemented in mgfilt is really that much worse.

I uploaded a short report on the comparison here:

http://static.larsgrobe.de/spec2Yxy-20131115.pdf

Cheers, Lars.

Hi Lars,

I'm pretty sure mgfilt does its calculation with an equal-energy white, not D65 or any of the other standard illuminants. Try repeating it with EE white to see what you get.

Cheers,
-Greg

ยทยทยท

Sent from my iPad

On Nov 15, 2013, at 3:27 PM, "Lars O. Grobe" <[email protected]> wrote:

Hi,

mgfilt is not really part of the core Radiance package, but typically
used with Radiance. So I hope this is not entirely off-topic.

I have been using mgfilt from time to time as a convenient tool for
getting color coordinates from measured reflection spectra. However some
results appeared a bit strange, and thus I did a comparision with what I
get from mgfilt and the results of using the CIE formulae with rcalc
instead. To make it short, the results I got from mgfilt were quite off,
and I am wondering wether I did something wrong or the accuracy
implemented in mgfilt is really that much worse.

I uploaded a short report on the comparison here:

http://static.larsgrobe.de/spec2Yxy-20131115.pdf

Cheers, Lars.