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Jai Ganesh

Administrator

Registered: 2005-06-28

Posts: 48,638

Brightness

Brightness

Gist

The quality of shining with, or of producing, a lot of light.

Details

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.

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 Q.  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 Proto-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. Brightness is an antonym of "dimness" or "dullness".

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

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.

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paulb203

Member

Registered: 2023-02-24

Posts: 334

Re: Brightness

Is brightness synonymous with intensity, which is measured by a wave's amplitude?

On the EM spectrum there is ultraviolet light and visible light; are the other rays/waves on the spectrum considered as light also (gamma rays; x-rays; infrared radiation; microwaves; radio waves)?

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