Illuminance
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In photometry, illuminance is the total luminous flux incident on a surface, per unit area. It is a measure of how much the incident light illuminates the surface, wavelength-weighted by the luminosit
A lux meter for measuring illuminances in work environments
Illuminance diagram with units and terminology
Luminance
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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 reflec
Illuminance
…that is used in photography. Illuminance was formerly often called brightness, but this leads to confusion with other uses of the word, such as to mean luminance. "Brightness" should never be used for quantitative description, but only for nonquantitative references to physiological sensations and perceptions…
A tea light-type candle, imaged with a luminance camera; false colors indicate luminance levels per the bar on the right (cd/m2)