Use readPixels to read a block of pixels, and getPixel to get the value of a single pixel. The raster number. The pixel to be set. This routine is more efficient than readPixels for getting the value of a single pixel, but is a lot less efficient if a block of pixels are to be read. All parameters except the mapping number are output parameters.
All parameters are input parameters.
The offset and scale parameters may be used to adjust the brightness and contrast of the image when the colormap is loaded. Colormap zero is the hardware colormap. By following graphics pipelines back to the original source raster we mean the following. This is a convenience routine for changing only the flip portion of a mapping. This destroys all markers and initializes the marker subsystem.