Trichromacy

Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Trichromacy or trichromaticism is the condition of possessing three independent channels for conveying color information, derived from the three different cone types. Organisms with trichromacy are called trichromats. The normal explanation of trichromacy is that the organism's retina contains three types of color receptors (called cone cells in vertebrates) with different absorption spectra. In actuality the number of such receptor types may be greater than three, since different types may be active at different light intensities. In vertebrates with three types of cone cells, at low light intensities the rod cells may contribute to color vision, giving a small region of tetrachromacy in the color space. The trichromatic color theory began in the 18th century, when Thomas Young proposed that color vision was a result of three different photoreceptor cells.