> Right. That's exactly what I meant with my "color is > perception" comment. Colour perception is a very complex thing. Back in my undergraduate days, I went to a conference on the use of colour in computing, and one of the seminars was on colour perception. Two examples have stuck strongly in my mind. Lights were turned off, and then a strong white light was shone onto a black card. The lecturer then placed a white card so that it partially covered the black card, and yes, we all agreed that it was white. He then took another card and said "if that first one was white, what's this?" He placed it onto the first white card... and it was whiter, the first white card now looking slightly grey. He repeated this 4 or 5 times, each time the new card he placed looked white, and the older cards turned greyer. When the room lights came back up, the first card was maybe a 50% grey and not white at all. The second one involved some slides. THe picture was of a living room and had a yellow cushion sitting on a chair. The second slide was a copy of the first slide, except a small piece of translucent blue plastic had been affixed over the yellow cushion, turning it distinctly green. The third slide was the same slide again, but with the blue plastic now covering the whole slide. If you'd taken RGB data of the cushion, it would have been exactly the same as in the second slide. However, it was clearly yellow again. In fact, you can see similar perception examples here : http://www.echalk.co.uk/amusements/OpticalIllusions/illusions.htm (Check out colour perception and colour perception 2, though the other illusions are cool too!) Timothy