Dichromacy in humans's a moderately severe color vision defect in which one of the three basic color mechanisms's absent or not functioning. It's hereditary and sex-linked, predominantly affecting males. Dichromacy occurs when one of the cone pigments's missing and color's reduced to two dimensions. Organisms with dichromacy are called dichromats. Dichromats can match any color they see with a mixture of no more than two pure spectral lights. By comparison, a trichromat requires three pure spec… (More on Dichromacy)