Journal of the Korean Institute of Telematics and Electronics C (전자공학회논문지C)
- Volume 36C Issue 9
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- Pages.76-84
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- 1999
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- 1226-5853(pISSN)
Improvement of Flexible Zerotree Coder by Efficient Transmission of Wavelet Coefficients
웨이블렛 계수의 효율적인 전송에 따른 가변제로트리코더의 성능개선
- Joo, Sang-Hyun (Dept. Electronics Eng. Dongguk Univ.) ;
- Shin, Jae-Ho (Dept. Electronics Eng. Dongguk Univ.)
- Published : 1999.09.01
Abstract
EZW proposed by Shapiro is based on a zerotree constructed in a way that a parent coefficient in a subband is related to four child coefficients in the next finer subband of similar orientation. This fixed treeing based on 1-to-4 parent-child is suitable to exploti hierachical correlations among subbands but not to exploit spatial correlations within a subband. A new treeing by Joo, et al. is suggested to simulatneously exploit those two correlatins by extending parent-child relationship in a flexible way. The flexible treeing leads to increasing the number of symbols and lowering entorpy comparing to the fixed treeing, and therefore a better compression can be resulted. In this paper, we suggest two techniques to suppress the increasing of symbols. First, a probing bit is generated to avoid redundant scan for insignivicant coefficients. Second, since all subbands do not always require the same kind of symbol-set, produced symbols are re-symbolized into binary codes according to a pre-defined procedure. Owing to those techniques, all symbols are generated as binary codes. The binary symbols can be entropy-coded by an adaptive arithmetic coding. Moerover, the binary symbol stream can give comparatively good performances without help of additional entropy coding. Our proposed coding scheme is suggested in two modes: binary coding mode and arithmetic coding mode. We evaluate the effectivenessof our modifications by comparing with the original EZW.
Shaprio가 발표한 EZW에서는 한 대역의 부(父)계수가 유사방향의 인접 고주파대역에 4개의 자(子)계수들과 부자관계를 구성하는 고정트리를 기반으로 한다. 이러한 고정트리는 대역간의 계층적 상관관계를 고찰하는데는 적합할 수 있으나, 4개의 계수가 하나의
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