| Theory | Explanation of Color Vision |
|---|
| Trichromatic theory | There are three types of cones, each only activated by wavelength ranges of light corresponding roughly to blue, green, and red; all colors are mixtures of various levels of activation of these three types of cones |
| Opponent-process theory | There are three opponent-process cell systems (red-green, blue-yellow, and black-white) that process color information after it has been processed by the cones; the colors in each system oppose one another (if one is stimulated, the other is inhibited) |
| Composite theory | Color information is processed by the cones according to trichromatic theory, but color information is processed at the post-receptor cell level according to opponent-process theory |