| Summary: | 碩士 === 南台科技大學 === 電子工程系 === 99 === The Discrete Wavelet Transform (DWT), which decomposes a signal into its components in different frequencies, can be considered as multi-resolution signal analysis. The pictures transformed through DWT and then encoded by using Embedded Zerotree Wavelet (EZW) coding, which has the property of progressive transmission.
The thesis aims at reducing the length of the encoded symbols
generated by EZW coding. To reduce the computing complexity, the pictures are partitioned into several 8*8 pixels blocks. Each block is transformed through DWT. To reduce the distortion caused by the block effect, the block compensation method has been added while doing DWT. Then the DWT coefficients are EZW coded. Finally, the number of coded symbols can be reduced by using the Burrows-Wheeler Transform (BWT). Experimental results show that our method achieves 1 to 9 percent improvement in compression ratio over the previous EZW coding method.
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