Цветовой круг: организация и принципы построения

Illustrative organization of color hues

A color wheel or color circle is an abstract illustrative organization of color hues around a circle, which shows the relationships between primary colors, secondary colors, tertiary colors etc. Some sources use the terms color wheel and color circle interchangeably; however, one term or the other may be more prevalent in certain fields or certain versions as mentioned above. For instance, some reserve the term color wheel for mechanical rotating devices, such as color tops, filter wheels or the Newton disc. Others classify various color wheels as color disc, color chart, and color scale varieties.

In his book Opticks, Isaac Newton presented a color circle to illustrate the relations between these colors. The original color circle of Isaac Newton showed only the spectral hues and was provided to illustrate a rule for the color of mixtures of lights, that these could be approximately predicted from the center of gravity of the numbers of "rays" of each spectral color present (represented in his diagram by small circles). The divisions of Newton's circle are of unequal size, being based on the intervals of a Dorian musical scale. Most later color circles include the purples, however, between red and violet, and have equal sized hue divisions. Color scientists and psychologists often use the additive primaries, red, green, and blue; and often refer to their arrangement around a circle as a color circle as opposed to a color wheel. Thomas Young postulated that the eye contains receptors that respond to three different primary sensations, or spectra of light. James Clerk Maxwell showed that all hues, and almost all colors, can be created from three primary colors such as red, green, and blue, if they are mixed in the right proportions. Goethe's Theory of Colours provided the first systematic study of the physiological effects of color (1810). His observations on the effect of opposed colors led him to a symmetric arrangement of his color wheel anticipating Ewald Hering's opponent color theory (1872). text= for the colours diametrically opposed to each other are those that reciprocally evoke each other in the eye.|author=Goethe|title=Theory of Colours

Most color wheels are based on three primary colors, three secondary colors, and the six intermediates formed by mixing a primary with a secondary, known as tertiary colors, for a total of 12 main divisions; some add more intermediates, for 24 named colors. They make use of the trichromatic model of color.

The typical artists' paint or pigment color wheel includes the blue, red, and yellow primary colors. The corresponding secondary colors are green, orange, and violet or purple. The tertiary colors are green yellow, yellow orange, orange red, red violet/purple, purple/violet blue and blue green. Non digital visual artists typically use red, yellow, and blue primaries (RYB color model) arranged at three equally spaced points around their color wheel. Printers and others who use modern subtractive color methods and terminology use magenta, yellow, and cyan as subtractive primaries. Intermediate and interior points of color wheels and circles represent color mixtures. In a paint or subtractive color wheel, the "center of gravity" is usually (but not always) black, representing all colors of light being absorbed.

A color wheel based on RGB (red, green, blue) additive primaries has cyan, magenta, and yellow secondaries. Alternatively, the same arrangement of colors around a circle can be described as based on cyan, magenta, and yellow subtractive primaries, with red, green, and blue being secondaries. Sometimes a RGV (red, green, violet) triad is used instead. In an additive color circle, the center is white or gray, indicating a mixture of different wavelengths of light (all wavelengths, or two complementary colors, for example). The HSL and HSV color spaces are simple geometric transformations of the RGB cube into cylindrical form. The outer top circle of the HSV cylinder – or the outer middle circle of the HSL cylinder – can be thought of as a color wheel. There is no authoritative way of labelling the colors in such a color wheel, but the six colors which fall at the corners of the RGB cube are given names in the X11 color list, and are named keywords in HTML.

Some color wheels are based on the four opponent process colors red, yellow, blue and green. This includes those of the Natural Color System.

A color circle based on spectral wavelengths appears with red at one end of the spectrum and is 100% mixable violet at the other. A wedge shaped gap represents colors that have no unique spectral frequency. These extra spectral colors, the purples, form from an additive mixture of colors from the ends of the spectrum. In normal human vision, wavelengths of between about 400 nm and 700 nm are represented by this incomplete circle, with the longer wavelengths equating to the red end of the spectrum. Complement colors are located directly opposite each other on this wheel. These complement colors are not identical to colors in pigment mixing (such as are used in paint), but when lights are additively mixed in the correct proportions appear as a neutral grey or white. The color circle is used for, among other purposes, illustrating additive color mixture. Combining two colored lights from different parts of the spectrum will produce a third color that appears like a light from another part of the spectrum, even though dissimilar wavelengths are involved. This type of color matching is known as metameric matching. A similar calculation cannot be performed with two paints. As such, a painter's color wheel is indicative rather than predictive, being used to compare existing colors rather than calculate exact colors of mixtures. Because of differences relating to the medium, different color wheels can be created according to the type of paint or other medium used, and many artists make their own individual color wheels. These often contain only blocks of color rather than the gradation between tones that is characteristic of the color circle.

A number of interactive color wheel applications are available both on the Internet and as desktop applications. These programs are used by artists and designers for picking colors for a design.