imProcessCalcAutoGamma

Calculates an automatic gamma factor. \n * gamma=log((mean-min)/(max-min))/log(0.5); * Usefull for \ref imProcessToneGamut when using IM_GAMUT_POW. * * \verbatim im.ProcessCalcAutoGamma(image: imImage) -> gamma: number [in Lua 5] \endverbatim * \ingroup tonegamut