Patent ID: 6891550

Claim:
A graphics program, comprising: (a) a first buffer for storing values representing the pixels of a region, (b) a second buffer for storing values representing the pixels of a region, (c) a plurality of functions for mapping input pixel values to output pixel values, (d) input means for selecting a function with which pixels of the region are to be processed, (e) input means for describing the strength and area of an alpha channel in the region, (f) a processor for computing a new set of pixel values, comprising: (1) means for calculating an output for each pixel with the selected function applied to it, (2) means for comparing the output pixels with the pixel values of the second buffer, according to the alpha channel described, to produce a set of resultant pixel values, and (3) means for installing the resultant pixel values into the first buffer, and (g) input means for requesting that the pixel values be copied from the first buffer to the second, and (h) means for copying the pixel values of said first buffer into said second buffer.