Vision , Light , and Color
Color is universally experienced as an important aspect of vision. Although almost everyone sees the colors of the sky, earth, grass, flowers, and all other visible objects, and although there seems to be general agreement about what these colors appear to be, exactly what color is can be somewhat puzzling.
We tend to think of it as a characteristic of an objects or a surface-but it can be demonstrated. That the same object can appear different in color under various circumstance. A scientific approach to the study of color has brought about an understanding of what color is, so that any study of color must now begin with knowledge of the basic physical principles that underline all color effects.
Whether we choose to define color as the mental or psychological impression created in the mind of a viewer by a particular observed object or surface, or we define it as the stimulus that produces such mental impressions, is a matter of choice. Like the question of whether a falling tree in the forest makes a sound if no one is present to hear it, whether color is the stimulus or the sensation produced by the stimulus is a semantic ( or perhaps a philosophical ) matter. In scientific terms, the choice makes little different. All color study must begin with understanding the working of the human eye.
The human ( and many animal ) eyes are devices for collecting information. In a form that can be delivered to the brain. Such visual information is collected by the ability of the eye to convert experience of light into signals. That can be transmitted to the brain by nerve impulses. The lens of the eye focuses lights onto the sensitive retina much as the lens of a camera focuses light onto the surface of the film or plate. Without light, neither the camera nor the eye ca operate.
We cannot see in total darkness; to see well, we need adequate light falling on the scene we wish to view. How much light is adequate is a matter that concerns lighting designers but is incidental to this discussion. The light of a candle or a match makes vision possible under limited circumstances. The light of the sun in daytime is more than adequate for vision in most familiar situations.
How the eye and brain convert the images that the lens casts on the retina into an understanding of three-dimensional reality is a complex matter constantly under study in the field usually called visual perception.
It becomes clear that light is itself a carrier of information that the eye and brain can interpret as color.