What I've emphasized is obviously not the "real news" of the article.
Might be of interest to the "Sir Frederick" sub-tradition of this
group.

Color Contrast Is 'Seen' By The Brain Early Doors
http://www.eurekalert.org/pub_releases/2007-09/du-cci090707.php

#EXCERPT# Dr Robert Kentridge, lead researcher and lecturer in Durham
University's Psychology Department explains: "Colour is a product of
our nervous system--it is a 'pigment' of our imagination. The colours
that we see are more related to the materials that things are made of
than the light reflected from them into our eyes. Making this happen
involves many complex processes. One of the earliest involves seeing
contrast between pairs of colours. We have found that this important
step of seeing colour contrast happens much earlier in the brain than
we had realised up to now.

"..... Professor Charles Heywood, who leads Durham's Psychology
Department, added: "People can distinguish between colours partly
because of the contrast with its background. If someone has lost that
ability through brain damage, it means that they might see colours as
changing all the time. The colour of clothes, and indeed everything
else we see, would change dramatically, depending on the colour of
light which shines on them."