A zerotree image-coding scheme is introduced that effectively exploits the inter-scale self-similarities found in the octave decomposition by a wavelet transform. A zerotree is usuful for efficiently coding wavelet coefficients ; its efficiency was proved by Shapiro's EZW. In the EZW coder, wavelet coefficients are sympolized, then entropy-coded for further compression. In this paper, we analyze the symbols produced by the EZW coder and discuss the entropy for a symbol. We modify the procedure used for symbol-stream generation to produce lower entropy. First, we modify the fixed relation between a parent and children used in the EZW coder to raise the propability that a significant parent has significant children. The modified relation is flexibly modified again based on the observation that a significant coefficient is more likely to have significant coefficients in its neighborhood. The three relations are compared in terms of the number of symbols they produce.
雑誌名
IEICE transactions on communications
巻
E81-B
号
12
ページ
2528 - 2535
発行年
1998-12
出版者
The Institute of Electronics, Information and Communication Engineers
A new image coding technique with low entropy using a flexible zerotree
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