glPixelTransfer()
Pixel Transfer
GL_INDEX_
SHIFT
OFFSET
GL_
RED
GREEN
BLUE
ALPHA
DEPTH
_SCALE
_BIAS
Post-Convolution
GL_POST_CONVOLUTION_
RED
GREEN
BLUE
ALPHA
_SCALE_EXT
_BIAS_EXT
Post-Color Matrix
GL_POST_COLOR_MATRIX_
RED
GREEN
BLUE
ALPHA
_SCALE_EXT
_BIAS_EXT