Color perception requires specific photoreceptors. The photoreceptor rhodopsin (right), which absorbs light in the process of vision, consists of the protein opsin and a bound vitamin A derivative, retinal. The amino acids (shown in red) that surround the retinal determine the color of light that is most efficiently absorbed. A person lacking a light-absorbing photoreceptor for the color green will see a bowl of fruits of many colors (left) as similar shades of yellow-green (middle).