Error detection and concealment in JPEG images

Even with use of restart intervals, some residual errors remain in the decoded JPEG images after transmission. In order to improve the image quality, robust decoding techniques are useful. First, we propose error detection techniques, then error compensation and concealment techniques for the damaged blocks. Depending on the entropy coding and on the neighbourhood template, improvements between 3 and 7 dB in terms of Peak-to-peak Signal-to-Noise Ratio (PSNR) are provided by robust decoders with respect to conventionnal JPEG decoders, under bit error rates around and less than 10⁻⁴.