Talk:Brightness

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This page is incorrect. It misses completely the use of brightness as a term in astronomy used to discuss the irradiance or radiant emittance from a star and measured in W/m^2.

Brightness is correctly defined as a lowercase b and is equal to the luminosity of the star, L, divided by 4 * pi * r^2 where r is the distance from the star to the surface the brightness is being measured.

This is a similar problem with luminosity, as astronomy and color theory both claim the same words. I.m.o., make a disambiguation page for the definition in astronomy. 217.122.183.107 (talk) 17:04, 11 April 2013 (UTC)
Brightness is also a technical term used in the paper industry, where it apparently means something like luminance. The three standards for defining and measuring it are TAPPI Standard T451 (more commonly known as GE), ISO Standard 2469 (or ISO for short) and something called D65. When you buy a ream of copier paper in the USA, the label will have something like: "Domtar First Choice MultiUse Copy Paper - Legal - 8.5" x 14" - 24lb - Smooth - 98 GE/114 ISO Brightness - 5000 / Carton - White" In the TAPPI method, nearly all uv is filtered out of the grading lamps, while the ISO standard simulates daylight. The Optical Brightening Agents in white paper exhibit very strong blue fluorescence. In the paper industry, brightness is measured in a 40 nm band centered around 457 nm. This is how paper can have an albedo greater than 100%. Zyxwv99 (talk) 15:24, 2 May 2013 (UTC)