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Human color vision

Human color vision is based on three color sensitive cells, cones in the human eye. Color stimulus is formed in the brain and the color seen, is based on the relative distribution of these three stimuli. The perceived color of an object is dependent not only on the color of the object but also on the illumination, where the object is looked at. In Figure, there is a schematic drawing of formation of color stimulus in the human eye.



Figure. Color stimulus is generated by the color signal reaching the human retina. Color signal is a product of color spectrum of illumination and reflectance spectrum of an object. The activity of each cone cell into this color signal depends on the sensitivity of the cone. The cone cell response, which is sent to the brain, is a product of color signal and the cone sensitivity. The brain recognizes the color of the object based on these three cone cell response.