A rasterizer for generating pixel values for a pattern generation apparatus. The pixel values drive the printing mechanism of the pattern generation apparatus. The rasterizer receives a file defining the pattern to be printed, fractures the pattern into sub frames, rasterizes each sub frame and then coordinates the provision of the shaded pixel values to the pattern generation apparatus. The rasterizer of the present invention is comprised primarily of a host processing means for fracturing and translating the file into one or more sub frames of pixels; geometry engines for rasterizing each sub frame; beam boards for providing the pixel shading values to a pattern generation system; a serial bus for coupling the host processor means to the geometry engines and beam boards and a pixel bus for coupling each of the geometry engines to each of the beam boards.