A wavelet packet based block-partitioning image coding algorithm with rate-distortion optimization

Image coding methods based on wavelet packet decomposition show more potential than those based on usual wavelet transform since wavelet packet presents an effective tool for adaptive waveform analysis. However, most of current work adopts zerotree quantization methods inside the wavelet packet framework, and these quantization methods are proved to be inappropriate for wavelet packet subbands. In this paper, we present an image coding algorithm based on a rate-distortion optimized wavelet packet decomposition and on a block-partitioning coding scheme which quantizes each subband separately. In this way, our algorithm naturally overcomes the difficulty in defining parent-child relationships for wavelet packet subbands, which exists in the zerotree based methods. The experimental results show that the proposed algorithm significantly outperforms SPIHT and JPEG2000 schemes and also surpasses recent wavelet packet based image coding algorithms, in terms of both PSNR and visual quality.