Efficient shape-adaptive zero tree coding scheme and its FPGA implementation for DWT based progressive coding

Shape adaptive processing is essential in an object based video codec system (e.g. MPEG-4) to reduce the computing complexity. An efficient shape-adaptive zero tree coding scheme and its hardware realization are presented for real time still texture coding using DWT. The wavelet coefficients obtained from a shape adaptive DWT core are passed onto the proposed design for progressive coding. We adopt the approach of zero tree coding but take advantage of the shape mask information to eliminate totally the coding overheads of pixels outside the video object. The proposed coding scheme features both shape adaptive and progressive coding. Simulation results indicate that under given bit rates, a 4dB PSNR performance edge over the SPIHT algorithm can be obtained. The corresponding hardwired design is next derived while the counterpart for the SPIHT algorithm has been considered as too complicated to be realized in hardware. The FPGA implementation results show that the logic gate count is less than 10K and a sustained processing rate of 20 1024×1024 sized frames/sec can be obtained.