Image filtering with orthogonal projectors for burst error control

The design of image prefilters for error control is considered and seen to be closely related to the problem of designing antialiasing filters to precede signal decimation. Intrafield codes are introduced, some of which can be implemented with fewer than 1 multiplier per 100 pixels. These codes have a great advantage in a bandlimited TV environment over alternative error-control methods requiring no redundancy, since they depend on prefiltering of the image. The primary implementation cost is, therefore, that of intrafield processors at the source and receiver. These processors consist primarily of a field store and of simple arithmetic units implementing vertical line (comb). filtering. In the optimal filters discussed, most coefficients are ±1´s. An application to compatible coding of TV signals for control of impulse errors in NTSC signals is presented. The emphasis is on encoding by vertical filtering and burst error estimation