In color models (such as the CIE color space), an alternate term for lightness. See Lightness.
Luminance is also defined as the luminous intensity of a surface or object, or the amount of light that is radiated or reflected by that surface or object. Luminance is measured in terms of the photometric brightness of a surface as viewed from a given direction per unit of area of the surface in that direction, such as candles per square meter or lumens per square foot (also called footlamberts).
In video and television production, luminance refers to the brightness of a video signal, which can be controlled independently of chrominance, which is the color information. See Chrominance.