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A short introduction to the physics, perception, specification, and use of color. This document is intended primarily for technical writers and user interface designers.

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Table of Contents

1. Why is color important?
2. The physics of color
3. Color perception
4. Modeling color space
4.1. The Ostwald diagram
4.2. The color wheel and the RGB color model
4.3. The hue-saturation-value (HSV) color model
4.4. The CMY model
4.5. The CMYK model

1. Why is color important?

A working understanding of the physics of color, and how humans perceive color, is most useful in technical writing and in engineering design.

If you use color to convey information, in a user interface or in documentation, there are many things to keep in mind.

  • Section 2, “The physics of color” discusses color from a scientific viewpoint.

  • Section 3, “Color perception” discusses how we perceive color. Not everyone sees color the same way; a substantial fraction of humans have some form of color-blindness.

  • There are several different useful ways to describe colors; see Section 4, “Modeling color space”.

  • Consider the cultural differences in the interpretation of color. In the USA, red often means danger, but in China, red is the color of good fortune.

  • The legibility of text can be affected strongly by the contrast between foreground and background colors. Dark letters on a black background are hard to read. Some combinations of bright colors, such as bright green text on a pink background, are difficult to ignore, even annoying; this may be a good practice (as when you are trying to attract attention) or a bad practice (as when you would prefer that your readers or users not hate you).

  • If you want your colors to be rendered in the same way on paper as on a display device, it is important to understand the limitations of printing and display devices. We touch on this problem in Section 4.5, “The CMYK model”.