Error control coding of television signals by multidimensional filtering

The design of image prefilters for error control is considered and seen to be dual to the well-known problem of designing anti-aliasing filters for signal decimation. Filters formed from unitary transforms are seen to yield computationally efficient two-step implementations obtained by orthogonal decomposition. Filters which perform optimally in the presence of background noise are introduced and seen to require only P multiplications for each column of N pixels, where P=2 and N=240 for TV signals in NTSC format. The amount of signal distortion due to this prefiltering is small and often imperceptible