| Summary: | 碩士 === 國立雲林科技大學 === 電子與資訊工程研究所碩士班 === 91 === Object-based coding technology is the main stream of the research for visual coding in the future. Shape adaptive processing is essential in an object based video codec system (e.g. MPEG-4) to reduce the computing complexity. In this thesis, an efficient shape-adaptive zero tree coding scheme and its hardware realization are presented for the 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 totally eliminate the coding overheads of pixels outside the video object. The proposed coding scheme features both shape adaptive and progressive coding. Simulation results indicate the encoder for a 256×256 image requires 149 k bits memory compared with the 2048 K bits in the original design. In addition, under given bit rates, an average of 4dB PSNR performance edge over the SPHIT algorithm can be obtained. The corresponding hardwired design is next derived while the counterpart for SPHIT algorithm has been considered as too complicated to be realized in hardware. The FPGA implementation results show that the SA-DWT logic gate count is 20K and SA-ZTC Codec logic gate count is less than 10K, In terms of performance, sustained processing rate of 20 1024�e1024 sized frames/sec can be obtained.
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