오류에 강인한 Wavelet 기반의 정지 영상 부호화 기법에 관한 연구
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Recently, as there are proliferation of wireless services and the internet along with demands for the multimedia products, many effective image compression techniques using wavelet transform have been developed. The zerotree wavelet coding technique that uses properties of statistics, energy and directions of wavelet coefficients in the time-space-frequency domain is one of them. It gives the outstanding performance with the low computational complexity. These algorithm are highly dependent on the state of the system and are, therefore, highly susceptible to bit errors. A single bit error could potentially lead to decoder derailment so that it would degrade the whole image quality severely. In the proposed algorithm, the image is encoded by the 2D EZW(Embedded Zerotree Wavelet) algorithm using the zerotree technique. The encoded bitstreams are partitioned into minimum length blocks using the subband correlations and then the Resync markers are inserted before them. In the decoding stage, error-concealment is implemented using interpolation and data recovery algorithm. Interpolation is performed by correlation of wavelet subbands and Data recovery is performed by RVLC(Reversible Length Coder). Simulation results have shown that the proposed algorithm based on the zerotree wavelet coding technique performs more effective error-concealment than the conventional coding techniques in the objective and the subjective evaluations, In low BER(Bit Error Rate), the proposed algorithm has shown better performance in terms of PSNR(Peak Signal to Noise Ratio) than the conventional methods and similar performance to the conventional methods when approaching to high BER environment.