Enhancement of PCM and DPCM Images Corrupted by Transmission Errors

Simple methods for enhancing PCM and DPCM monochrome pictures corrupted by transmission bit errors are described. For PCM signals the enhancement is achieved by operating exclusively on the corrupted image, without recourse to any side-information from the transmitter. The DPCM signals have simple protection codewords that increase the bit rate by 12 percent (if majority protection coding is used). Photographs of the original, corrupted, and enhanced images are presented, together with SNR as a function of percentage bit error rate (BER) for the corrupted and enhanced picture. For 0.1<;BER<;1.0, the SNR gains for PCM and DPCM are ≃10 and 18 dB, respectively. For BER<;0.05 percent there is imperceptible picture degradation.