The convolution kernels are themselves treated as one- and two- dimensional images. They can be loaded from application memory or from the framebuffer.
Convolution is performed only for RGBA pixel groups, although these groups may have been specified as color indexes and converted to RGBA by index table lookup.
Figure 7-2 shows the equations for general convolution at the top and for separable convolution at the bottom.
Figure 7-2 : Convolution Equations