Change detection and texture analysis for image sequence coding

摘要

In Hybrid DPCM image sequence coders, every block with high variance in the corresponding difference block is replenished even if it belongs to a stationary background region, as could be the case for coarse textured blocks. We present an improved Hybrid DPCM image sequence coder, which includes a block classification unit. This unit detects stationary textured background blocks and allows copying such blocks instead of replenishing them, thus reducing the bit-rate of the coder. The unit consists of three parts. The first part is a statistical-based change detector. Segmentation of each image into textured and smooth regions, a fast converging deterministic relaxation procedure and a multi-resolution approach are used to obtain the final moving/stationary segmentation. In the second part, a Gaussian AR model-based texture matching test is proposed. The third part detects edges in stationary blocks. To avoid edge related artifacts, blocks that contain an edge are unconditionally coded. The coder which incorporates the proposed change detector was found, in simulations, to provide a substantial reduction in bit-rate, while maintaining the quality of the reconstructed sequences, in coding image sequences which contain large areas of coarse textured background.