color

color effect produced on the eye and its associated nerves by light waves of different wavelength or frequency. Light transmitted from an object to the eye stimulates the different color cones of the retina, thus making possible perception of various colors in the object.

See also light ; painting ; protective coloration ; vision .

The Visible Spectrum

Since the colors that compose sunlight or white light have different wavelengths, the speed at which they travel through a medium such as glass differs; red light, having the longest wavelength, travels more rapidly through glass than blue light, which has a shorter wavelength. Therefore, when white light passes through a glass prism , it is separated into a band of colors called a spectrum . The colors of the visible spectrum, called the elementary colors, are red, orange, yellow, green, blue, indigo, and violet (in that order).

Apparent Color of Objects

Color is a property of light that depends on wavelength. When light falls on an object, some of it is absorbed and some is reflected. The apparent color of an opaque object depends on the wavelength of the light that it reflects; e.g., a red object observed in daylight appears red because it reflects only the waves producing red light. The color of a transparent object is determined by the wavelength of the light transmitted by it. An opaque object that reflects all wavelengths appears white; one that absorbs all wavelengths appears black. Black and white are not generally considered true colors; black is said to result from the absence of color, and white from the presence of all colors mixed together.

Additive Colors

Colors whose beams of light in various combinations can produce any of the color sensations are called primary, or spectral, colors. The process of combining these colors is said to be "additive" ; i.e., the sensations produced by different wavelengths of light are added together. The additive primaries are red, green, and blue-violet. White can be produced by combining all three primary colors. Any two colors whose light together produces white are called complementary colors, e.g., yellow and blue-violet, or red and blue-green.

Subtractive Colors

When pigments are mixed, the resulting sensations differ from those of the transmitted primary colors. The process in this case is "subtractive," since the pigments subtract or absorb some of the wavelengths of light. Magenta (red-violet), yellow, and cyan (blue-green) are called subtractive primaries, or primary pigments. A mixture of blue and yellow pigments yields green, the only color not absorbed by one pigment or the other. A mixture of the three primary pigments produces black.

Properties of Colors

The scientific description of color, or colorimetry, involves the specification of all relevant properties of a color either subjectively or objectively. The subjective description gives the hue, saturation, and lightness or brightness of a color. Hue refers to what is commonly called color, i.e., red, green, blue-green, orange, etc. Saturation refers to the richness of a hue as compared to a gray of the same brightness; in some color notation systems, saturation is also known as chroma. The brightness of a light source or the lightness of an opaque object is measured on a scale ranging from dim to bright for a source or from black to white for an opaque object (or from black to colorless for a transparent object). In some systems, brightness is called value. A subjective color notation system provides comparison samples of colors rated according to these three properties. In an objective system for color description, the corresponding properties are dominant wavelength, purity, and luminance. Much of the research in objective color description has been carried out in cooperation with the Commission Internationale de l'Eclairage (CIE), which has set standards for such measurements. In addition to the description of color according to these physical and psychological standards, a number of color-related physiological and psychological phenomena have been studied. These include color constancy under varying viewing conditions, color contrast, afterimages, and advancing and retreating colors.

Symbolic Uses of Color

Color has long been used to represent affiliations and loyalties (e.g., school or regimental colors) and as a symbol of various moods (e.g., red with rage) and qualities (e.g., worthy of a blue ribbon). A well-known use of the symbolism of color is in the liturgical colors of the Western Church, according to which the color of the vestments varies through the ecclesiastical calendar; e.g., purple (i.e., violet) is the color of Advent and Lent; white, of Easter; and red, of the feasts of the martyrs.

Bibliography

See G. Wyszecki and W. S. Stiles, Color Science (1967); M. W. Levine and J. M. Shefner, Fundamentals of Sensation and Perception (1991).

color n.
1. the flag of a regiment or ship.

2. a national flag.

3. the armed forces of a country, as symbolized by its flag: he was called to the colors during the war.

col·or / ˈkələr/ (Brit. col·our) • n. 1. the property possessed by an object of producing different sensations on the eye as a result of the way the object reflects or emits light. ∎  one, or any mixture, of the constituents into which light can be separated in a spectrum or rainbow, sometimes including (loosely) black and white. ∎  the use of all colors, not only black, white, and gray, in photography or television: he has shot the whole film in color | [as adj.] color television. ∎  a substance used to give something a particular color: lip color. ∎ fig. a shade of meaning: many events in her past had taken on a different color. ∎ fig. character or general nature: the hospitable color of his family. ∎ Heraldry any of the major conventional colors used in coats of arms (gules, vert, sable, azure, purpure), esp. as opposed to the metals, furs, and stains. 2. the appearance of someone's skin; in particular: ∎  pigmentation of the skin, esp. as an indication of someone's race: discrimination on the basis of color. ∎  a group of people considered as being distinguished by skin pigmentation: all colors and nationalities. ∎  rosiness of the complexion, esp. as an indication of someone's health. ∎  redness of the face as a manifestation of an emotion, esp. embarrassment or anger. 3. vividness of visual appearance resulting from the presence of brightly colored things: for color, plant groups of winter-flowering pansies. ∎ fig. picturesque or exciting features that lend a particularly interesting quality to something. ∎  fig. variety of musical tone or expression: orchestral color. 4. (colors) an item or items of a particular color or combination of colors worn to identify an individual or a member of a school, group, or organization; in particular: ∎  the clothes or accoutrements worn by a jockey or racehorse to indicate the horse's owner. ∎  the flag of a regiment or ship. ∎  a national flag. ∎  the armed forces of a country, as symbolized by its flag: he was called to the colors during the war. 5. Physics a quantized property of quarks which can take three values (designated blue, green, and red) for each flavor. 6. Mining a particle of gold remaining in a mining pan after most of the mud and gravel have been washed away. • v. 1. [tr.] change the color of (something) by painting or dyeing it with crayons, paints, or dyes. ∎  [intr.] take on a different color: the foliage will not color well if the soil is too rich. ∎  use crayons to fill (a particular shape or outline) with color. ∎ fig. make vivid or picturesque. 2. [intr.] (of a person or their skin) show embarrassment or shame by becoming red; blush: everyone stared at him, and he colored slightly. ∎  [tr.] cause (a person or their skin) to change in color: rage colored his pale complexion. ∎  [tr.] (of a particular color) imbue (a person's skin): a pink flush colored her cheeks. ∎  [tr.] fig. (of an emotion) imbue (a person's voice) with a particular tone. 3. [tr.] influence, esp. in a negative way; distort: the experiences had colored her whole existence. ∎  misrepresent by distortion or exaggeration: witnesses might color evidence to make a story saleable. PHRASES: person of color see person of color. show one's true colors reveal one's real character or intentions, esp. when these are disreputable or dishonorable. with flying colors see flying.