@blahh:
Coloring the Universe: Why Reality is a Gray Area in Astronomy

"...Levay says the process of coloring photos is never arbitrary.

"What we're doing is representing physical processes and representing actual astronomical observations in a visual and artistic way," Levay explained shortly after discussing the issue with Brecher. "I'm adding value, but it's not arbitrarily added. What I'm mostly doing is enhancing what's already there...."

Glad you brought the point up and made me want to know how that worked.