Brightness

Brightness is an attribute of visual perception in which a source appears to emit a given amount of light. In other words, brightness is the perception elicited by the luminance of a visual target.

Related Topics:
Visual perception - Light - Luminance

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"Brightness" was formerly used as a synonym for the photometric term luminance and (incorrectly) for the radiometric term radiance.

Related Topics:
Photometric - Luminance - Radiometric - Radiance

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"Brightness" should now be used only for nonquantitative references to physiological sensations and perceptions of light.

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Source: Federal Standard 1037C

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Note, that the same target luminance can elicit different perceptions of brightness in different contexts. (See, e.g. White's illusion and Wertheimer-Benary illusion)

Related Topics:
White's illusion - Wertheimer-Benary illusion

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In the RGB color space, brightness can be thought of as the arithmetic mean μ of the Red, Green, and Blue color coordinates (although some of the three components make the light seem brighter than others, which, again, may be compensated by some display systems automatically):

Related Topics:
RGB color space - Arithmetic mean

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: mu = {R + G + B over 3 }.

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Brightness is also a color coordinate in HSB color space.

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With regard to stars etc. see apparent magnitude, absolute magnitude.

Related Topics:
Star - Apparent magnitude - Absolute magnitude

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