Optimum Restoration Of Coded And Transmitted Images
Michael N. Huhns · Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE · 1976
A restoration technique is derived that can simultaneously reduce the degrading effects of a digital image coding operation and mitigate the effects of channel errors that arise when the encoded information is transmitted. The technique optimally reduces these degradations with respect to a mean-square-error criterion and is applied entirely a posteriori to a received visual signal. The restoration is based upon four factors--the multidimensional probability density function of a typical undegraded image, parameters of the encoding operation, the structure of the channel and its error probabilities, and the received visual signal. The technique is applied to the restoration of DPCM coded images which have been transmitted over a binary symmetric channel. The restored images which result exhibit a decrease in mean-square error and a subjective improvement in visual quality.