Brightness is an attribute of
visual perception in which a source appears to be radiating or reflecting
light. In other words, brightness is the
perception elicited by the
luminance of a visual target. The perception is not linear to luminance, and relies on the context of the viewing environment (for example, see
White's illusion).
Brightness is a subjective sensation of an object being observed and one of the
color appearance parameters of many
color appearance models, typically denoted as
. Brightness refers to how much light ''appears to shine'' from something. This is a different perception than
lightness, which is how light something appears ''compared to'' a similarly lit white object.
The adjective ''
bright'' derives from an Old English ''
beorht'' with the same meaning via metathesis giving Middle English ''briht''. The word is from a
Common Germanic ', ultimately from a
PIE root with a closely related meaning, *' "white, bright".
"Brightness" was formerly used as a synonym for the
photometric term ''
luminance'' and (incorrectly) for the
radiometric term ''
radiance
In radiometry, radiance is the radiant flux emitted, reflected, transmitted or received by a given surface, per unit solid angle per unit projected area. Radiance is used to characterize diffuse emission and reflection of electromagnetic radiati ...
''. As defined by the US ''Federal Glossary of Telecommunication Terms'' (
FS-1037C), "brightness" should now be used only for non-quantitative references to physiological sensations and perceptions of light.
[�]
Brightness
�� in Federal Standard 1037C, the ''Federal Glossary of Telecommunication Terms'' (1996)
With regard to
stars, brightness is quantified as
apparent magnitude and
absolute magnitude.
Brightness is an antonym of
dimness or dullness.
New meaning
The United States
Federal Trade Commission (FTC) has assigned an unconventional meaning to brightness when applied to
lamps. When appearing on light bulb packages, brightness means
luminous flux, while in other contexts it means luminance.
Luminous flux is the total amount of light coming from a source, such as a lighting device. Luminance, the original meaning of brightness, is the amount of light per solid angle coming from an area, such as the sky. The table below shows the standard ways of indicating the amount of light.
See also
*
Brightness (sound)
*
Luma (video)
In video, luma represents the brightness in an image (the "black-and-white" or achromatic portion of the image). Luma is typically paired with chrominance. Luma represents the achromatic image, while the chroma components represent the color infor ...
*
Luminance (relative)
*
Luminosity
* The difference between luminescence and brightness is practically exploited by
prism lighting
Notes
External links
Poynton's Color FAQ
{{Authority control
Vision
Photometry
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