Color Theory Research

Color fills our world with beauty. We delight in the colors of a magnificent sunset and in the bright red and golden-yellow leaves of autumn. We are charmed by gorgeous flowering plants and the brilliantly colored arch of a rainbow. We also use color in various ways to add pleasure and interest to our lives. For example, many people choose the colors of their clothes carefully and decorate their homes with colors that create beautiful, restful, or exciting effects. By their selection and arrangement of colors, artists try to make their paintings more realistic or expressive.

Color serves as a means of communication. In sports, different colored uniforms show which team the players are on. On streets and highways, a red traffic light tells drivers to stop, and a green light tells them to go. On a map printed in color, blue may stand for rivers and other bodies of water, green for forests and parks, and black for highways and other roads.

We use the names of colors in many common expressions to describe moods and feelings. For example, we say a sad person feels blue and a jealous one is green with envy. We say an angry person sees red. A coward may be called yellow.

Color plays an important part in nature. The brilliant colors of many kinds of blossoms attract insects. The insects may pollinate the flowers, causing the plants to develop seeds and fruits. Colorful fruits attract many kinds of fruit-eating animals, which pass the seeds of the fruits in their droppings. The seeds may then sprout wherever the droppings fall. In this way, fruit-bearing plants may be spread naturally to new areas.

The colors of some animals help them attract mates. For example, a peacock spreads his brightly colored feathers when courting a female. The colors of many other animals help them escape from enemies. For example, Arctic hares have brownish fur in summer. In winter, their fur turns white, making it difficult for enemies to see the hares in the snow.

Although we speak of seeing colors or objects, we do not actually see them. Instead, we see the light that objects reflect or give off. Our eyes absorb this light and change it into electrochemical signals. The signals travel through nerves to the brain, which interprets them as colored images. However, there is much that scientists still do not know about how our eyes and brain enable us to sense color.

This article discusses COLOR (History of color studies).

The relation between color and light

To understand how we see color, we must first know something about the nature of light. Light is a form of energy that behaves in some ways like waves. Light waves have a range of wavelengths. A wavelength is the distance between any point on one wave and the corresponding point on the next wave. Different wavelengths of light appear to us as different colors. Light that contains all wavelengths in the same proportions as sunlight appears white. See LIGHT.

When a beam of sunlight passes through a specially shaped glass object called a prism, the rays of different wavelengths are bent at different angles. The bending breaks up the sunlight into a beautiful band of colors. This band contains all the colors of the rainbow and is called the visible spectrum. At one end of the spectrum, the light appears as violet. It consists of the shortest wavelengths of light that we can see. Farther along the spectrum, the light has increasingly longer wavelengths. It appears as blue, green, yellow, orange, and red, each shading into its neighboring colors in the spectrum. The longest wavelengths of light that we can see appear deep red in color. Some descriptions of the spectrum also mention the color indigo, which is closely related to blue, between violet and blue.

Light waves are a form of electromagnetic waves, which consist of patterns of electric and magnetic energy. The visible spectrum is only a small part of the electromagnetic spectrum-the entire range of electromagnetic waves. Beyond the violet end of the visible spectrum are ultraviolet rays, X rays, and gamma rays. Beyond the red end of the visible spectrum are infrared rays and radio waves. See ELECTROMAGNETIC WAVES.

Such objects as traffic lights and neon signs appear colored because the light that they give off contains a limited range of wavelengths. However, most objects appear colored because their chemical structure absorbs certain wavelengths of light and reflects others. When sunlight strikes a carrot, for example, molecules in the carrot absorb most of the light of short wavelengths. Most of the light of longer wavelengths is reflected. When these longer wavelengths of light reach our eyes, the carrot appears orange.

An object that reflects most of the light of all wavelengths in nearly equal amounts appears white. An object that absorbs most of the light of all wavelengths in nearly equal amounts appears black.

How we see color

The roles of the eyes and brain. Our ability to see color depends on many highly complicated workings of the eyes and brain. When we look at an object, light coming from the object enters our eyes. Each eye focuses the light, forming an image of the object on the retina. The retina is a thin layer of tissue covering the back and sides of the inside of the eyeball. It contains millions of light-sensitive cells. These cells absorb most of the light that falls on the retina and convert the light to electrical signals. These electrical signals then travel through nerves to the brain.

The retina has two main types of light-sensitive cells--rods and cones. The cells are named after their shapes. Rods are extremely sensitive to dim light but cannot distinguish wavelengths. For this reason, we see only tones of gray in a dimly lit room. As the light becomes brighter, the cones begin to respond and the rods cease functioning. The retina of a person with normal color vision has three types of cones. One type responds most strongly to light of short wavelengths, which corresponds to the color blue. Another type reacts chiefly to light of middle wavelengths, or green. The third type is most sensitive to light of long wavelengths, or red.

The brain organizes nerve signals from the eye and interprets them as colored visual images. Exactly how the brain makes us aware of colors is still much of a mystery. Scientists have developed several theories to explain color vision. Some of these theories are discussed in the section History of color studies.

Some people do not have full color vision. Such people are said to be color blind. There are different types