brightness

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



Q


{\displaystyle 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 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.With regard to stars, brightness is quantified as apparent magnitude and absolute magnitude.
Brightness is an antonym of dimness or dullness.

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