Transmission error detection and concealment in JPEG images

摘要

The robustness to transmission errors of JPEG coded images is investigated and techniques are proposed to reduce their effects. After an analysis of the JPEG transfer format, three main classes of transfer format constituents are distinguished, and a JPEG compatible approach is proposed to stop error propagation in the entropy coded data, with encoder and decoder reset after fixed coding interval lengths.With the use of restart intervals, the propagation of errors is stopped but no correction has taken place. Therefore, a concealment procedure is defined and investigated. It consists of two steps. First, error detection must be performed and three different techniques are assessed and compared. Then, block error concealment is achieved.Simulation results are reported. Depending on the entropy coding and on the neighborhood templates used for detection and concealment, prediction based or interpolation based, improvements between 3 and 10 dB in peak-to-peak signal-to-noise ratios (PSNR) are provided by the robust decoder with respect to conventional JPEG decoders, for bit error rates around 10−4.