Digital video signal filtering to produce a double-sided impulse response

摘要

Video signals are subjected to a filtering process in which the signals are multiplied by a first variable gain coefficient and a delayed sample of the signals is derived by a delay circuit and the delayed sample is multiplied by a second variable gain coefficient. The two multiplied signals are added together. The magnitudes of the first and second gain coefficients are varied in dependence upon a comparison between the input video signal relative to the delayed sample from the delay circuit and in an opposite sense to one another. By a suitable choice of the gain coefficients, the filtering process can be used to preserve the sharpness of large transitions in picture information and the impulse response of the filter can be readily modified by re-calculating the gain coefficient. The filtering process may be used in a cascade of stages to achieve filtering in vertical, horizontal and temporal domains.