Brightness

Brightness

Brightness

Perception of light level

For other uses, see Brightness (disambiguation).

Brightness is an attribute of visual perception in which a source appears to be radiating or reflecting light.[1] 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).

Decreasing brightness with depth (underwater photo as example)

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.[2]

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 *berhtaz, ultimately from a PIE root with a closely related meaning, *bhereg- "white, bright". "Brightness" was formerly used as a synonym for the photometric term luminance and (incorrectly) for the radiometric term radiance. 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.[3] Brightness is an antonym of "dimness" or "dullness".

With regard to stars, brightness is quantified as apparent magnitude and absolute magnitude.

Two pictograms resembling the Sun with rays are used to represent the settings of luminance in display devices. They have been encoded in Unicode since version 6.0 (October 2010) in the Miscellaneous Symbols and Pictographs block under U+1505 as "low brightness symbol" (๐Ÿ”…) and U+1F506 as "high brightness symbol" (๐Ÿ”†).[4]

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.[5] 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.

More information Quantity, Unit ...
  1. [N 1]
    The symbols in this column denote dimensions; "L", "T" and "J" are for length, time and luminous intensity respectively, not the symbols for the units litre, tesla and joule.
  2. [N 2]
    Standards organizations recommend that photometric quantities be denoted with a subscript "v" (for "visual") to avoid confusion with radiometric or photon quantities. For example: USA Standard Letter Symbols for Illuminating Engineering USAS Z7.1-1967, Y10.18-1967
  3. [N 3]
    Alternative symbols sometimes seen: W for luminous energy, P or F for luminous flux, and ฯ for luminous efficacy of a source.

See also

References

  1. [1]
    "Bright Definition & Meaning", Merriam-Webster Dictionary.
  2. [2]
    Robert William Gainer Hunt: Some comments on using the CIECAM97s colour-appearance model
  3. [3]
    โ€œBrightnessโ€ in Federal Standard 1037C, the Federal Glossary of Telecommunication Terms (1996)
  4. [4]
    "Miscellaneous Symbols and Pictographs" (PDF). Unicode Consortium. 2023.
  5. [5]
    "Shopping for Light Bulbs". United States Federal Trade Commission. Retrieved March 13, 2017.

Media related to brightness at Wikimedia Commons

Look up brightness in Wiktionary, the free dictionary.
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This article uses material from the Wikipedia article Brightness, and is written by contributors. Text is available under a CC BY-SA 4.0 International License; additional terms may apply. Images, videos and audio are available under their respective licenses.