Gamma correction

Gamma correction or gamma is a <a href="/facts/Nonlinearity/4aYItALC">nonlinear</a> operation used to encode and decode <a href="/facts/Relative_luminance/cvSXAI7s">luminance</a> or <a href="/facts/CIE_1931_color_space/fzgwzV8V">tristimulus values</a> in <a href="/facts/Video/F1AV8ben">video</a> or <a href="/facts/Still_image/hbjEdTXK">still image</a> systems. Gamma correction is, in the simplest cases, defined by the following <a href="/facts/Power_law/DhAjYwwz">power-law</a> 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.

Gamma correction open-in-new

Gamma correction