A method for performing black trapping and under print processing on image data from a raster image processing (RIP) frame buffer is provided. The image data includes pixel data according to a predetermined color space (e.g., RGB) and may include black rendering hints. If black rendering hints are not included, the method includes steps to determine if each pixel from the frame buffer is black or black with respect to predetermined thresholds. Three further embodiments of the method are provided in regard to CMY under print values for a black pixel when all pixels of a context window surrounding the black pixel are black. One embodiment provides no CMY under print. Another embodiment provides a predefined CMY under print. Still another embodiment provides an adaptive CMY under print based on the last saved CMY under print value.