Dichromacy

Dichromacy is a form of color vision with two dimensions. Dichromatic humans have a Color Vision Deficiency compared to Color Normals. However, most mammals are Dichromats and have color vision very similar to Protanopes or Deuteranopes. Dichromacy is more severe than Anomalous Trichromacy but not as severe as Monochromacy.

Dichromats have two Cones. In humans, this means that one of their typical 3 Cones (L-cone, M-cone or S-cone) is missing or completely dysfunctional. The three forms of Dichromacy are Protanopia, Deuteranopia and Tritanopia, depending on which cones is missing.