Scalable Image Coding Method Based on Zerotrees of Wavelet Coefficients

摘要

Based on the property of wavelet transform and the advantage of Shapiro's EZW coding algorithm, this paper proposed a scalable still image coding method using zerotrees of wavelet coefficients. Firstly form a subband pyramid and quantize all wavelet coefficients using uniform scalar quantizer. Secondly encode the magnitude of nonzero wavelet coefficients at low frequency subband in bit plane order. Finally beginning from coarsest resolution subband of high frequency and ending at finest resolution subband of high frequency, independently search for all nonzero wavelet coefficients in each subband using zerotrees and encode them in bit plane order separately. Differing significantly from Shapiro's, our approach endows the bit stream with the multirate and the multiresolution property simultaneously. Experiment results show that our coding method is superior to the EZW algorithm in PSNR and visual effect.