Light receptors within the eye transmit messages to the brain, which produces the familiar sensations of color. Newton observed that color is not inherent in objects. Rather, the surface of an object reflects some colors and absorbs all the others. We perceive only the reflected colors.
Can you imagine colors that don’t exist?
If you can imagine a reddish green or a bluish yellow, you can imagine an impossible color, which in theory you have never seen. There is some evidence to suggest that it is possible to observe one of these “impossible colors” by having one eye view one color and one eye view the other.