#include "SDL.h"
int SDL_SetGamma(float redgamma, float greengamma, float bluegamma);
Sets the "gamma function" for the display of each color component. Gamma controls the brightness/contrast of colors displayed on the screen. A gamma value of 1.0 is identity (i.e., no adjustment is made).
This function adjusts the gamma based on the "gamma function" parameter, you can directly specify lookup tables for gamma adjustment with SDL_SetGammaRamp.
Not all display hardware is able to change gamma.
Returns -1 on error (or if gamma adjustment is not supported).
SDL_GetGammaRamp SDL_SetGammaRamp