Gamma Correction
By default, Glide does not perform gamma correction (i.e. a linear ramp is used), however gamma correction is available. A gamma value can be passed to the hardware using the Glide function grGammaCorrectionValue().
void grGammaCorrectionValue( float value ) 
grGammaCorrectionValue() sets the gamma correction value used during video refresh. Gamma is a positive floating point value from 0.0 to 20.0. Typical values are 1.3 to 2.2. The default value is 1.0 (i.e. a linear ramp is used).

The displayed RGB value (RGBgamma) is computed from the RGB value read from the frame buffer (RGBfb) according to the following equation:

RGBgamma = [(RGBfb/255)1/gamma]*255 

Chapter 5                                                                                                                   Next : Chapter 6