Colours

Color (American English) or colour (Commonwealth English) is the characteristic of human visual perception described through color categories, with names such as red, yellow, purple, or bronze. This perception of color derives from the stimulation of cone cells in the human eye by electromagnetic radiation in the spectrum of light. Color categories and physical specifications of color are associated with objects through the wavelength of the light that is reflected from them. This reflection is governed by the object's physical properties such as light absorption, emission spectra, etc. Human trichromacy is the basis for all modern color spaces that assign colors numerical coordinates and associate corresponding distances between colors.

The photo-receptivity of the "eyes" of other species also varies considerably from our own and so results in presumably different color perceptions that cannot readily be compared to one another. The mere presence of "extra" photoreceptor types does not directly imply that they are being used functionally in an animal. Demonstrating improved spectral discrimination in any animal can be difficult since complex sets of neurons affect color perception in ways that are generally difficult to interrogate.

The science of color is sometimes called chromatics, colorimetry, or simply color science. It includes the perception of color by the human eye and brain, the origin of color in materials, color theory in art, and the physics of electromagnetic radiation in the visible range (that is, what is commonly referred to simply as light).

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