sol 72 R7B6 of TEGA soil:

mann, mann, mann.
Please read the Flickr comments in the linked image.
The color map used was ( R, G, B ) = ( R7, RB, R6 ). Note that the flag colors are not correct.
I did a little analysis of the surface soil visible in the upper right and the TEGA soil that shows a slight increase in the brightness -- but most likely not meaningful.
Remember, in our tourist snaps any color comparisons must be in the same picture to have any meaning.
( Gee, Uncle Howard is purple -- but so is Aunt Helen -- Maybe it's the green cheese they are eating? )