Luminance
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The word luminance, a synonym for luminosity, means emitting or reflecting light.
As applied to analog television signals, two different words are used, luminance and luma, meaning two different things. Luma is a new word proposed by the NTSC in 1953 to prevent confusion between the Y' component of a color signal and the traditional meaning of luminance. While luminance is the weighted sum of the linear RGB components of a color video signal, proportional to intensity, luma is the weighted sum of the non linear R'G'B' components after gamma correction has been applied, and thus is not the same as either intensity or luminance.
An incorrect luma setting can cause visible flicker in a television display.
SI light units
| Quantity | SI unit | Symbol | Notes | |
|---|---|---|---|---|
| Luminous energy | joule | J | ||
| Luminous flux | lumen or ( candela · steradian ) | lm | also called Luminous power | |
| Luminous intensity | candela | cd | ||
| Luminance | candela / square metre | cd/m2 | also called Luminosity | |
| Illuminance | lux or (lumen / square metre) | lx | ||
| Luminous efficacy | lumens per watt | lm/w | ||
See also
fr:Luminance sv:Luminans
