This document discusses color interaction with the human eye. It explains that color is a perceptual response to light entering the eye. The eye contains photoreceptors called cones that are sensitive to different wavelengths of light, including long (L), medium (M), and short (S) wavelengths. The cones detect light and send signals to the brain where color perception occurs. Spatial vision and color contrast also impact color perception, as the context of a color stimulus affects its appearance.