Gamma correction is achieved by raising the color to a power, the power being the gamma value. So sqrt is the same as gamma correction with gamma = 2.0; On typi

Gamma correction is achieved by raising the color to a power, the power being the gamma value. So sqrt is the same as gamma correction with gamma = 2.0; On typical monitors, gamma is 2.2 , so this is close and maybe faster if the GPU has optimizations for fast square root. More info : http://http.developer.nvidia.com/GPUGems3/gpugems3_ch24.html http://http.developer.nvidia.com/GPUGems3/gpugems3_ch24.html