An embedded wavelet image coder with parallel encoding and sequential decoding of bit-planes

Abstract

Wavelet-based coders are widely used in image compression. Many popular embedded wavelet coders are based on a data structure known as zerotree. However, there exists another category of embedded wavelet coders that are fast and efficient without employing zerotree. These coders are based on three key concepts: (1) wavelet coefficient reordering, (2) bit-plane partitioning, and (3) encoding of bit-planes with certain efficient variants of run-length coding. In this paper, we propose a novel method to construct a bit-plane encoder that can be used in this category of non-zerotree coders. Instead of encoding the bit-planes progressively, the bit-plane encoding process can be finished in one pass when multiple bit-plane encoders are activated concurrently. With this proposed method, traditional partitioned-block based parallel processing strategy is enhanced with another dimension (depth of bit-planes) of processing flexibility. This bit-plane encoder inherently targets parallel processing architecture. The final output bitstream can be compatible with that of the original sequential coder if compatibility is preferred over speed and memory efficiency.