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Many people refer to problems with one’s ability to see color as , however, unless a person can’t see any color at all, color vision problems should be called by another term. Common terms are abnormal color vision, color deficiency and color vision confusion ....

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.... only three color sensitivities. Therefore, the huge variety of colors we see are a response to different compositions of wavelengths of light. The rods are responsible for encoding white and black. results when one or more of the cone cells fail to function properly. One of the visual pigments may be functioning abnormally, or be absent altogether. There are several different types of , however, complete , or achromatopsia, is probably the simplest to understand. This is the rarest form of . This is when no colors can be seen at all. The color receptors are almost completely gone in this form, however, the white and black receptors remain intac ....