Color Theory

“In visual perception, a color is almost never seen as it really is—as it physically is.”—Josef Albers

Color is fundamental to many forms of art. Its relevance, use and function in a given work depend on the medium of that work. While some concepts dealing with color are broadly applicable across media, others are not.

The full spectrum of colors is contained in white light. Humans perceive colors from the light reflected off objects. A red object, for example, looks red because it reflects the red part of the spectrum. It would be a different color under a different light.

Light can be split up into a spectrum by sending it through a prism. This was discovered by Isaac Newton, who is the creator of color theory.

Color Theory
The study of color in art and design often starts with color theory. Color theory splits up colors into three categories: primaries, secondaries, and tertiaries.

The basic tool used is a color wheel, developed by Isaac Newton in 1666. Another model, the color tree, was created by Albert Munsell. It has a spectrum made up of sets of tints and shades on connected planes.

Theory Variations
There are a number of approaches to organizing colors into meaningful relationships. Most systems differ in structure only. Among these, three systems are consistently used in the contemporary art world.

Traditional Model
Traditional color theory is a qualitative attempt to organize colors and their relationships. It is based on Newton's color wheel, and continues to be the most common system used by painters and printmakers.


 * Traditional color theory uses the same principles as subtractive color mixing (see below) but prefers different primary colors.


 * The Primary colors are red, blue, and yellow. These are the "elemental" colors, because they cannot be produced by mixing other colors together, and all other colors are derived from some combination of these three.


 * The Secondary colors are orange (mix of red and yellow), green (mix of blue and yellow), and purple (mix of blue and red).


 * The Tertiary colors are obtained by mixing one primary color and one secondary color. Depending on amount of color used, different hues can be obtained such as red-orange or yellow-green. Neutrals (browns and grays) can be made by mixing all three primaries together.


 * White and black lie outside of these categories. They are used to lighten or darken a color. A lighter color (made by adding white to it) is called a tint, while a darker color (made by adding black) is called a shade.

Color Mixing
A more quantifiable approach to color theory is to think about color as the result of light reflecting off a surface. Understood in this way, color can be represented as a ratio of amounts of primary color mixed together. In this system, primary colors are chosen by dividing up the visible spectrum into thirds and making each third a primary.

Whether a color is being determined by the light source being reflected or the surface reflecting it makes a significant difference in the way colors interact with one another. This distinction is blurred when working with digital technology where production environments and product often move fluidly between these media types.


 * Additive color theory is used when different colored lights are being projected on top of each other. Projected media produce color by projecting light onto a reflective surface.  Where subtractive mixing creates the impression of color by selectively absorbing part of the spectrum, additive mixing produces color by selective projection of part of the spectrum.  Common applications of additive color theory are theater lighting and television screens.  RGB color is based on additive color theory.


 * The Primary colors are red, blue, and green.


 * The Secondary colors are yellow (mix of red and green), cyan (mix of blue and green), and magenta (mix of blue and red).


 * The Tertiary colors are obtained by mixing the above colors at different intensities.


 * White is created by mixing the three primary colors while black represents the absence of all colors. The lightness or darkness of a color is determined by the intensity/density of its various parts.  For instance: a middle-toned gray could be produced by projecting a red, a blue and a green light at the same point with 50% intensity.


 * Subtractive color theory ("process color") is used when a single light source is being reflected by different colors laid one on top of the other. Color is produced when parts of the external light source's spectrum are absorbed by the material and not reflected back to the viewer's eye.  Subtractive color works as the reverse of additive color theory.  Common applications of subtractive color theory are color printing and photographic positives and negatives. The CMYK color model uses subtractive color theory. It was developed by Herbert Ives for printing.


 * The Primary colors are yellow, cyan, and magenta.


 * The Secondary colors are red (mix of magenta and yellow), blue (mix of cyan and magenta), and green (mix of cyan and yellow).


 * The Tertiary colors are obtained by mixing the above colors at different intensities.


 * Black is created by mixing the three primary colors while white represents the absence of all colors. (However, since it is impossible to mix a perfect black, and in order to save money and paper drying time, devices using process colors add black as a fourth "color." CMYK stands for Cyan, Magenta, Yellow, and Key (i.e., black). Similar to additive color theory, lightness/darkness is determined by color intensity/density.

Color Interactions
Beyond creating a mixing hierarchy, color theory also provides tools for understanding how colors work together.

Analogous Colors
Analogous colors are similar to one another. As their name implies, analogous colors can be found next to one another on any 12 part color wheel.


 * Common analogous colors can be found by taking one tertiary color and one of the secondary colors used by it when creating that tertiary color. note: examples using traditional color theory


 * purple/blue-purple.


 * green/yellow-green.


 * orange/red-orange.

A warm/cool scheme uses two pairs of analogous colors; one warm pair and one cool pair. (Intermixing should only be done within the pairs.)

Complementary Colors
Complementary colors are pairs of colors which, if added, would produce complete color saturation—white or black depending on the type of mixing you're doing. Complementary colors are found directly opposite one another on a color wheel.


 * Common complementary colors can be found by taking one secondary color and the primary color not used when creating that secondary color. note: examples using traditional color theory


 * violet/yellow.


 * green/red.


 * orange/blue.


 * white/black. Though they are not represented on the color wheel, adding white to black will always result in complete color saturation regardless of mixing method.

A double complementary scheme is made up of two complementary color pairs. (Intermixing may be done, but only within the pairs.)

A split complementary uses three hues, one color, and two others which are on each side of that hue's complement on the color wheel.

See also
 * color harmony

Attributes
The three attributes of color are hue, saturation, and value.

Hue
A hue is a pure, spectral color. Black and white are not hues.

Values
Color values range from low key (very dark) to high key (very light). 1 is absolute black, and 10 is pure white. Yellow is the hue with the lightest value, while violet is the darkest.

The value of a color can make a difference in how it is perceived. A color on a dark background will appear lighter, while that same color on a light background will appear darker.

Other Considerations
Other factors that affect how a piece looks are perception, and local color. Under what conditions will the piece be viewed? Since most art and design is looked at under ordinary (white) light, designers often buy bulbs that recreate that light.

Color quality is another concern. This can be affected by opacity or texture of media, or glossiness of surface.

Color Subtraction
A visual phenomenon where the appearance of one color will lessen its presence in a nearby color. For instance, orange (red + yellow) on a red background will appear more like yellow (RY − R = Y).

Simultaneous Contrast
Neutrals on a colored background will appear tinted toward that color's complement, because the eye attempts to create a balance. (Grey on a red background will appear more greenish, for example.) In other words, the color will shift away from the surrounding color.

Also, non-dominant colors will appear tinted towards the complement of the dominant color.

Color interaction affect values, as well. Colors appear darker on or near lighter colors, and lighter on or near darker colors. Complementaries will look more intense on or near each other than they will on or near grays.

Color for programmers
Color spaces

Color in scientific data visualisation

Misconceptions about colors
=See also=
 * Color Models: RGB, HSV, HSL from a computer graphics (Web page, image) perspective
 * Commons:Category:Color_theory