Spatial Filtering Using 3 X 3 Kernel Convolutions
J. T. Carlo, Joseph Hall · Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE · 1979
The equivalence of 3 x 3 linear discrete convolution filtering to spatial frequency domain multiplication is reviewed in this paper. DPCM (Differential Pulse Code Modulation) is simply a low pass filter in the frequency domain. More complex 3 x 3 filters allow the choice of a band stop locus in the frequency domain in order to reduce unwanted spatial frequency components. This real time spatial filtering is readily implemented using a multitapped CCD delay line coefficients on-chip with a CCD imager.