Predictive Image Coding with Pseudo-Laplacian Edge Detector

Several edge-adaptive dual-mode predictive coding systems are proposed for coding monochrome video signals. These algorithms use the pseudo-Laplacian edge detector to switch between the textural coding and the edge coding. The one-dimensional Song DM coder and the two-dimensional weighted average prediction DM coder were used for the textural coding. The edge coding was done with either a normal two-dimensional Song DM coder, Graham's DPCM schemes, or a DPCM coder developed by the authors. Nine different combinations of textural and edge coding techniques were developed and simulated. The bit rates of the various schemes were compared, and the range varied between 2.28-3.46 bits/pixel without further compression of the edge information bits or the correction bits. Subjective tests were carried out on images reconstructed according to these schemes. The results show that most of the pictures obtained with the techniques in this paper are superior to the pictures coded by the Song mode normal two-dimensional DM coder alone.