The ability of the eye to detect different wavelengths of light and to distinguish between these different wavelengths and their corresponding colours. In the mammalian eye this is achieved by the cone cells, which are located in and around the fovea near to the centre of the retina. The cone cells contain the light-sensitive pigment iodopsin, which exists in three forms (called photopsins), each occurring in a different cone cell and sensitive to a different range of wavelengths of light (originally proposed as the ‘trichromatic theory’). The relative stimulation of each type of cone will determine the colour that is interpreted by the brain. See also colour blindness.

Full colour vision is widespread among fishes, amphibians, reptiles, birds, and primates. The compound eye of certain insects is also capable of colour vision.