Seeing in Color by Sharon Himes

Artists need not be scientists but an understanding of the nature of color can help us mix and use color in our work. We know that light is a small part of the spectrum of electromagnetic waves that are patterns of energy pulsing through the universe. Different wavelengths of light appear to us as different colors. The longest wavelengths are red. A red traffic light emits a light at the wavelength for red.

The retina that is a tissue thin surface layer inside our eyeball has millions of cells that react to light and color. The two major types of light sensitive cells on this layer, called rods and cones, absorb most of the light and convert it to electrical signals. Rods are more common and fill much of the retina but although they are very sensitive to light and movement, they do not respond to the different wavelengths of light and thus do not see in color.

Cones are more tightly packed into an area of greater focus. There are three types of cones, each containing a different pigment that is sensitive to a particular wavelength of light. One type is stimulated by red wavelengths and sends an electrical signal to the brain expressing red. A second type reacts to green wavelengths. The third type, which is more common and scattered among the rods as well as the concentrated area of focus, reacts to blue.

Each rod and cone sends signals down the optical nerve, much like fiber optics might carry an image made of millions of tiny dots of color and shadow. We interpret the results and call it vision. Each viewer sees with a different set of eyes, however, and there are many variations in the number and sensitivity of rods and cones as well as the lens of the eye that the light travels through.

Artists with even mild cataracts may be seeing through a gold or orange tinted lens that unknowingly affects their color choices. Our sensitivity to light, night vision and other factors can change with age as likely as our clarity of vision. The physical qualities of sight influence every artist’s work.

Next: Painting in Color