DPCM ENCODER FOR TV SIGNALS USING SELECTIVE PREDICTION AND ENTROPY CODING.

A proposed DPCM encoder for monochrome television signals has been simulated. Its main features are entropy encoding and selective prediction. The range of differences is divided into three regions, fine, medium, and coarse, and 3-, 6-, and 10-bit codes, respectively, are transmitted for picture elements (pels) with differences in those regions. The prediction for the encoder is selective. For each segment of a specified number of pels, both horizontal and vertical predictions are performed using the nearest horizontal pel and the nearest vertical pel, respectively. The prediction that yields the smallest average bits/pel for the segment under consideration is then used for the transmission. One extra bit is transmitted with each segment to notify the receiver of the prediction which has been used. Simulation of this encoder shows that, at a transmission rate of 4. 5 bits/pel, there is no perceptible degradation between the original and reconstructed pictures. A transmission buffer of 4000 bits has been found to be adequate to accommodate the digitized TV signal.