Anomalous trichromacy

Anomalous trichromats have three cone photopigments and like normal trichromats, require three colors to match all spectral hues. However, the relative proportions of the three primaries required to make a color match are anomalous implying that one or more of the cone photopigments has abnormal absorption characteristics. The terms used are protanomalous, deuteranomalous and tritanomalous to describe the presence of abnormal 'red', 'green' and 'blue' photopigment respectively. Anomalous trichromats do not accept color matches made by normal trichromats and may not accept matches made by other anomalous trichromats in the same category. The severity of the defect also varies significantly between individuals.

The prevalence of the various forms of anomalous trichromacy are as follows: