IMBRIGHTNESS(r;l;h;m) modifies the brightness of the RGB image in matrix
r, setting pixels in each channel with brightness less than
l (default 0) to 0 and those brighter than
h (default 255) to 255;
m defines the mode of adjustment (default 0 stretches brightness and 1 distributes brightness evenly across the range).
Updated on December 4, 2017