Improved MPEG-4 VTC BQ Mode Coding Algorithm

Problem of scalable image coding is investigated from the viewpoint of consistency of zerotree symbol with the objective image of bitstream layer.An improved PEZW algorithm,SP-PEZW, is presented,in which a zerotree symbol is denoted by two decomposing symbols separately,and compression rates of the bitstream layers are improved by deleting the inconsistent decomposing symbols of the bitstream layers.Experiment results show that,comparing with PEZW algorithm,the bitrate of low resolution bitstream layer of SP-PEZW algorithm is lower,while bitrate of the highest resolution bitstream layer is the same,and image of the highest resolution spatial layer which is decoded at the special bitrate is better.Furthermore,SP-PEZW is implemented by adding a zerotree symbol decomposing coding module to the PEZW algorithm,and preserves the features such as random access,error resilience,localized coding,and low memory requirement.