Reversible predictive coding of continuous‐tone picture signals using block adaptive variable‐length codes — A scheme of reversible coding for picture data base

Abstract

AbstractIn the picture data base the allowable distortion is dependent on the various uses for each picture signal. an efficient reversible coding for continuous‐tone picture signals, which does not increase the distortions of PCM original picture signals, is necessary to construct the picture data base efficiently. In most of the former proposed reversible coding schemes, the compression characteristic deteriorates remarkably as the number of picture signal gradations is increased. In this paper, a scheme of reversible predictive coding using block adaptive variable‐length codes is proposed for 8 bit/6 bit PCM continuous‐tone picture signals. A simple method of selecting the appropriate variable‐length code in every block based upon threshold logic, which is designed by means of numerical calculation, is shown to be able to achieve almost the same efficiency as in the optimum selection scheme. Besides, a method of adapting its block size is introduced to cope with the block size dependency of the compression characteristic. This coding scheme yields a performance advantage of approximately 0.2 ‐ 0.4 bit/pel for 8 bit PCM picture signals and 0.11 ‐ 0.17 bit/pel for 6 bit PCM picture signals over Rice Machine 1.