Geometry in Color Perception

Abstract

Of the five human senses, only two can be excited essentially instantaneously by signals from distant sources: hearing and sight. In both cases, signals propagate as waves. It is not an accident therefore that we have television but not its equivalent in the realm of smell, taste or touch. Smell for example, propagates by diffusion, a slow process which is difficult to control, while taste and touch require immediate contact with the source of the signal. There is, however, a rather fundamental difference also between hearing and sight. Hearing occurs because sound excites cells in the cochlear tube of the inner ear and each little longitudinal section of the tube is sensitive to a different frequency. Consequently, we are capable of distinguishing a very large class of ‘sound profiles’. Thus, the space of sounds that human beings are capable of hearing has a very large dimension, which, for all practical purposes, can be taken to be infinite. This is in striking contrast with sight. It turns out that the space of colors that human beings are capable of seeing is only three dimensional!