Dichromatic vision

Guth, S. L. et al. (1980). Vector model for normal and dichromatic color vision. Journal of the Optical Society of America 70 197-212. 

Wooten, B. R. and G. Wald (1973). Color-vision mechanisms in the peripheral retinas of normal and dichromatic observers. Journal of General Physiology 61 125-145. 

Finlayson GD and Schaefer G 2001 Solving for colour constancy using a constrained dichromatic reflection model. International Journal of Computer Vision 42(3), 127-144. 

About 8% of males and less than 1% of females are born with defective color vision. As was discussed earlier, a person with normal color vision—the trichromat— has three kinds of color-sensitive cones red-, green-, and blue-sensitive cones. Dichromatism is when only two colors are perceptible and one color is difficult to recognize. 

The majority of persons, amounting to 92 per cent in the case of men, are trichromats, meaning that they have normal colour vision. When matching two or more shades with each other they make use of the three primaries. Between 2 and 3 per cent of men are dichromats because their eyes respond to only two primaries and their capacity to discriminate is less acute than that of the trichromats. 

Color Blindness (Deprecated) An incorrect term applied to defective color vision. An extremely small number of persons having complete lack of color response (are achromatopes). Most so-called colorblind persons are anomalous trichromats, seeing all three primaries but having responses which are weaker than normal to one of the primaries. Persons who lack response to one primary are called dichromats, seeing only two primaries. 

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