Colors the given raster data with the color ramp. The color ramp is stretched betweenminval and maxval, i.e. a value of minval in the raster is mapped to the pixel on the upper left
the value of maxval is mapped to the pixel on the top right. If the raster data is of the
data type byte, the color ray is deposited as a palette. Otherwise a colored
output file with RGB or RGBA channels is generated.