Color vision
Mathematics of color perception

Finally, since a beam of light can be composed of many different wavelengths, to determine the extent to which a physical color C in H stimulates each cone cell, we must calculate the integral (with respect to w), over the interval, of C (w)· s (w), of C (w)· m (w), and of C (w)· l (w). The triple of resulting numbers associates with each physical color C (which is an element in H) a particular perceived color (which is a single point in R). This association is easily seen to be linear. It may also easily be seen that many different elements in the "physical" space H can all result in the same single perceived color in R, so a perceived color is not unique to one physical color.
detectable_format:constrained_response