Color blindness
Cone cells receive the images that the eye sees in normal daylight or in bright light. There are three types of cone cells. Each type has a different chemical photopsin and reacts to a different spectrum of light. One is specially sensitive to short wavelengths. Another is sensitive to medium wavelengths. The third is sensitive to long wavelengths. These wavelengths cover much of the visible light. Each color is "seen" as a result of how much each of the receptors is stimulated.