Gamma correction

Gamma correction or gamma is a nonlinear operation used to encode and decode luminance in video or images. Gamma correction is, in the simplest cases, defined by the following power-law expression: V out = A V in γ , {\displaystyle V_{\text{out}}=AV_{\text{in}}^{\gamma },} where the non-negative real input value V in {\displaystyle V_{\text{in}}} is raised to the power γ {\displaystyle \gamma } and multiplied by the constant A to get the output value V out {\displaystyle V_{\text{out}}} . In the common case of A = 1, inputs and outputs are typically in the range 0–1. A gamma value γ < 1 {\displaystyle \gamma <1} is sometimes called an encoding gamma, and the process of encoding with this compressive power-law nonlinearity is called gamma compression; conversely, a gamma value γ > 1 {\displaystyle \gamma >1} is called a decoding gamma, and the application of the expansive power-law nonlinearity is called gamma expansion.