Which Color Space to Relax In ?

One of the questions regarding the color constancy process that I have is in which color space the operations should be performed. The lightness calculation is performed in sensor space, but the relaxation operation may be performed in either the sensor space or in another, luminance independent, space.

I repeated Test 7 in, doing the relaxation upon measurements in the original sensor color space (RGB) instead of upon the transformation of the sensor data into a chromaticity space (normalized red and blue in the original Test 7).

Here is the output of the relaxation performed in normalized red (R - Y) and normalized blue (B - y) color space :

Here is the output of the relaxation performed in RGB space, then transformed into chromaticity values and recombined with the original luminance signal :

This is simply the output of the relaxation performed in RGB space :

Also available are the histograms.

wad@media.mit.edu 12/96