> I assert that our understanding of the mathematics of harmonious color are well understood because the spectral relationships are fairly straightforward. I d

> I assert that our understanding of the mathematics of harmonious color are well understood because the spectral relationships are fairly straightforward. I definitely disagree with this. The relationship between color and spectrum is not straightforward. Again, the human perception of color is complicated and nonlinear. We have made great strides sussing out that relationship with experiment, but when we discuss hue and relative differences, it becomes far more difficult to translate our experimental data on human color perception to some kind of useful model. The models have evolved over the years, from tristimulus models (based on the spectral response of photoreceptors) to more complicated nonlinear perceptual models (Lab and its successors), but as we work towards more accurate perceptual models, the models become more complicated and therefore more difficult to use and understand. I am not trying to say this in order to be difficult--at one point I was working on image compression techniques and trying to create a perceptually uniform color quantization system. All models of color differences had noticeable limitations which made my work more difficult. > Thus 180 degrees being "correct" complementary. This assumes some kind of linearity in human visual perception which simply does not exist. You can do a hundred experiments showing that green light and magenta light mix to form white light, and yet this does not imply that they are complementary colors--the notion of complementary colors is only loosely related to the physics of light, just as color itself is only loosely related. One line of questioning here is, "Is it reasonable to consider red and green to be complementary colors? If so, should our color space encode this relationship?"