Brightness is an attribute of

visual perception Visual perception is the ability to interpret the surrounding environment through photopic vision (daytime vision), color vision, scotopic vision (night vision), and mesopic vision (twilight vision), using light in the visible spectrum reflecte ...

in which a source appears to be radiating or reflecting

light Light or visible light is electromagnetic radiation that can be perceived by the human eye. Visible light is usually defined as having wavelengths in the range of 400–700 nanometres (nm), corresponding to frequencies of 750–420 tera ...

. In other words, brightness is the

perception Perception () is the organization, identification, and interpretation of sensory information in order to represent and understand the presented information or environment. All perception involves signals that go through the nervous system ...

elicited by the

luminance Luminance is a photometric measure of the luminous intensity per unit area of light travelling in a given direction. It describes the amount of light that passes through, is emitted from, or is reflected from a particular area, and falls withi ...

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 White's illusion is a brightness illusion where certain stripes of a black-and-white grating are partially replaced by a gray rectangle (see the figure). Both of the gray bars of A and B have the same color and opacity. The brightness of the gray ...

). Brightness is a subjective sensation of an object being observed and one of the color appearance parameters of many

color appearance model A color appearance model (CAM) is a mathematical model that seeks to describe the perceptual aspects of human color vision, i.e. viewing conditions under which the appearance of a color does not tally with the corresponding physical measurement of ...

s, typically denoted as

Q

. Brightness refers to how much light ''appears to shine'' from something. This is a different perception than

lightness Lightness is a visual perception of the luminance (L) of an object. It is often judged relative to a similarly lit object. In colorimetry and color appearance models, lightness is a prediction of how an illuminated color will appear to a stan ...

, which is how light something appears ''compared to'' a similarly lit white object. The adjective ''

bright Bright may refer to: Common meanings *Bright, an adjective meaning giving off or reflecting illumination; see Brightness *Bright, an adjective meaning someone with intelligence People * Bright (surname) * Bright (given name) *Bright, the stage na ...

'' derives from an Old English ''

beorht Bert is a hypocoristic form of a number of various Germanic male given names, such as Robert, Albert, Elbert, Herbert, Hilbert, Hubert, Gilbert, Wilbert, Filbert, Norbert, Osbert, Bertram, Berthold, Bertrand, Umberto, Humbert, Cuthbert, Delber ...

'' with the same meaning via metathesis giving Middle English ''briht''. The word is from a

Common Germanic Proto-Germanic (abbreviated PGmc; also called Common Germanic) is the reconstructed proto-language of the Germanic branch of the Indo-European languages. Proto-Germanic eventually developed from pre-Proto-Germanic into three Germanic branc ...

', ultimately from a

PIE A pie is a baked dish which is usually made of a pastry dough casing that contains a filling of various sweet or savoury ingredients. Sweet pies may be filled with fruit (as in an apple pie), nuts ( pecan pie), brown sugar ( sugar pie), swe ...

root with a closely related meaning, *' "white, bright". "Brightness" was formerly used as a synonym for the photometric term ''

'' and (incorrectly) for the

radiometric Radiometry is a set of techniques for measuring electromagnetic radiation, including visible light. Radiometric techniques in optics characterize the distribution of the radiation's power in space, as opposed to photometric techniques, which cha ...

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 radiatio ...

''. As defined by the US ''Federal Glossary of Telecommunication Terms'' (

FS-1037C Federal Standard 1037C, titled Telecommunications: Glossary of Telecommunication Terms, is a United States Federal Standard issued by the General Services Administration pursuant to the Federal Property and Administrative Services Act of 1949, a ...

), "brightness" should now be used only for non-quantitative references to physiological sensations and perceptions of light. Brightness is an antonym of " dimness" or "

dullness Dullness may refer to: In vision *A lack of perceived brightness *A lack of perceived colorfulness In medicine *A dull sound in response to percussion (medicine) **Shifting dullness, a medical sign In philosophy and religion *Tamas (philosophy) ...

". With regard to

star A star is an astronomical object comprising a luminous spheroid of plasma (physics), plasma held together by its gravity. The List of nearest stars and brown dwarfs, nearest star to Earth is the Sun. Many other stars are visible to the naked ...

s, brightness is quantified as

apparent magnitude Apparent magnitude () is a measure of the brightness of a star or other astronomical object observed from Earth. An object's apparent magnitude depends on its intrinsic luminosity, its distance from Earth, and any extinction of the object's li ...

and

absolute magnitude Absolute magnitude () is a measure of the luminosity of a celestial object on an inverse Logarithmic scale, logarithmic Magnitude (astronomy), astronomical magnitude scale. An object's absolute magnitude is defined to be equal to the apparent mag ...

. Two pictograms resembling the Sun with rays are used to represent the settings of

display devices Display may refer to: Technology * Display device, output device for presenting information, including: ** Cathode ray tube, video display that provides a quality picture, but can be very heavy and deep ** Electronic visual display, output device ...

. They have been encoded in

Unicode Unicode, formally The Unicode Standard,The formal version reference is is an information technology Technical standard, standard for the consistent character encoding, encoding, representation, and handling of Character (computing), text expre ...

since version 6.0 (October 2010) in the Miscellaneous Symbols and Pictographs block under U+1505 as "low brightness symbol" (🔅) and U+1F506 as "high brightness symbol" (🔆). The United States

Federal Trade Commission The Federal Trade Commission (FTC) is an independent agency of the United States government whose principal mission is the enforcement of civil (non-criminal) antitrust law and the promotion of consumer protection. The FTC shares jurisdiction ov ...

(FTC) has assigned an unconventional meaning to brightness when applied to lamps. When appearing on light bulb packages, brightness means

luminous flux In photometry, luminous flux or luminous power is the measure of the perceived power of light. It differs from radiant flux, the measure of the total power of electromagnetic radiation (including infrared, ultraviolet, and visible light), in th ...

, 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.

References

External links

Poynton's Color FAQ
{{Authority control Vision Photometry hu:Világosság

See also

References

External links