Adaptive Edge Encoding Schemes for the Rate-Distortion Optimal Polygon-Based Shape Coding

In this paper, we present two adaptive edge encoding schemes for the operational rate-distortion optimal polygon-based shape coding. The encoding edge is represented by an octant number, a major component, and a minor component, where the ranges of the two components are determined at two levels. For the object-level, these ranges are either determined by users or adaptive to the contour characteristics and the predefined admissible distortions using the discrete contour evolution method. For the edge-level, the range of the minor component is further adaptive to the magnitude of the major component. The appropriate code tables are selected for the two components according to their ranges. Experiments on MPEG-4 test sequences showed that our schemes outperform existing schemes in terms of bit-rate at the same distortion level.