Ian Mallett wrote:
There is a "color space" that defines all possible colors. "Primary colors" are the colors we choose as basis vectors. Both red-blue-yellow and cyan-magenta-yellow are valid basis vectors;
I don't see how pure red, blue and yellow can be a valid subtractive basis. Pure yellow pigment absorbs all blue light, and pure blue pigment reflects only blue light. So yellow = -blue, and two of your basis vectors are not linearly independent. As far as I can see, red-blue-yellow only works to the extent that your blue is cyan-like, and it works better if your red is magenta-like. The best coverage of the colour space is obtained when the basis vectors are 120 degrees apart around the colour wheel. RGB and CMY are two such sets; RBY is not. Furthermore, anything other than RGB or CMY can't really be described as additive or subtractive -- it's somewhere in between. RGB is the only purely additive basis, and CMY is the only purely subtractive basis. So if you're going to talk about *the* subtractive basis, then it's CMY. -- Greg