What is Color?

We perceive color just as we perceive taste. When we eat, our taste buds sense four attributes: sweet, salty, sour and bitter. Point at the foods below and distinguish their different taste attributes.

Similarly, when we look at a scene, our visual nerves register color in terms of the attributes of color: the amount of green-or-red; the amount of blue-or-yellow; and the brightness. To see how colors are registered in terms of the attributes of color, point at the painting by Renoir below.

Color attributes were first understood by 19th century physiologist Ewald Hering, who made the color charts below. His charts show how all colors arise from a combination of green-or-red, blue-or-yellow and brightness. (In his diagram, the green-neutral-red is vertical, and blue-neutral-yellow is horizontal.) The left circle shows relative mixtures of color attributes. The right circle shows what we perceive when these attributes are mixed.