09-22-2021-1701 - Gamma correction or gamma

 

Gamma correction or gamma is a nonlinear operation used to encode and decode luminance or tristimulus values in videoor still image systems.^[1] Gamma correction is, in the simplest cases, defined by the following power-law expression:

where the non-negative real input value  is raised to the power  and multiplied by the constant A to get the output value . In the common case of A = 1, inputs and outputs are typically in the range 0–1.

A gamma value  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  is called a decoding gamma, and the application of the expansive power-law nonlinearity is called gamma expansion.

The effect of gamma correction on an image: The original image was taken to varying powers, showing that powers larger than 1 make the shadows darker, while powers smaller than 1 make dark regions lighter.

https://en.wikipedia.org/wiki/Gamma_correction