在众多的图像压缩算法中,SPIHT和SPECK具有较好的性能,文中对这两种算法进行了深入地研究.首先介绍了小波变换后系数的分布特点,然后从算法思想、集合定义、分裂过程、排序过程、量化以及编码后的码流等方面分别介绍了SPIHT(Set Partiti...在众多的图像压缩算法中,SPIHT和SPECK具有较好的性能,文中对这两种算法进行了深入地研究.首先介绍了小波变换后系数的分布特点,然后从算法思想、集合定义、分裂过程、排序过程、量化以及编码后的码流等方面分别介绍了SPIHT(Set Partitioning in H ierarchical Trees多级树集合分裂)和SPECK(Set Partitioning Embedded B lock Coder集合分裂嵌入块)算法,最后总结了他们的异同之处.展开更多
A new fractal image compression algorithm based on high frequency energy (HFE) partitioning andmatched domain block searching is presented to code synthetic aperture radar (SAR) imagery. In the hybridcoding algorithm,...A new fractal image compression algorithm based on high frequency energy (HFE) partitioning andmatched domain block searching is presented to code synthetic aperture radar (SAR) imagery. In the hybridcoding algorithm, the original SAR image is decomposed to low frequency components and high frequencycomponents by wavelet transform (WT). Then the coder uses HFE of block to partition and searchthe matched domain block for each range block to code the low frequency components. For the high frequencycomponents, a modified embedded zero-tree wavelet coding algorithm is applied. Experiment resultsshow that the proposed coder obtains about 0. 3dB gain when compared to the traditional fractal coderbased on the quadtree partition. Moreover, the subjective visual quality of the reconstructed SAR imageof the proposed coder outperforms that of the traditional fractal coders in the same compression ratio(CR).展开更多
In this paper, the authors propose a new approach to image compression based on the principle of Set Partitioning in Hierarchical Tree algorithm （SPIHT）. Our approach, the modified SPIHT （MSPIHT）, distributes entr...In this paper, the authors propose a new approach to image compression based on the principle of Set Partitioning in Hierarchical Tree algorithm （SPIHT）. Our approach, the modified SPIHT （MSPIHT）, distributes entropy differently than SPIHT and also optimizes the coding. This approach can produce results that are a significant improvement on the Peak Signal-to-Noise Ratio （PSNR） and compression ratio obtained by SPIHT algorithm, without affecting the computing time. These results are also comparable with those obtained using the Embedded Zerotree Wavelet （EZW） and Joint Photographic Experts Group 2000 （JPG2） algorithms.展开更多
A novel semi-fragile watermarking scheme for the content authentication of images using wavelet transform(WT) is presented in this paper.It is tolerant to the embedded wavelet image compression methods based on WT suc...A novel semi-fragile watermarking scheme for the content authentication of images using wavelet transform(WT) is presented in this paper.It is tolerant to the embedded wavelet image compression methods based on WT such as embedded zerotree wavelet(EZW) ,set partitioning in hierarchical trees(SPIHT) and embedded block coding with optimized truncation(EBCOT) in JPEG2000 to a pre-determined bit-plane,but is sensitive to all other malicious attacks.The image features are generated from the lowest-frequency(LF) subband of the original image as the embedded watermark.The watermark is embedded into the pre-determined bit-plane by adjusting the corresponding values in the given subband.In the process of watermarking authentication,we compare the image features generated from the LF subband of the received image with the embedded watermarking information(the image features of the original image) extracted from the pre-determined bit-plane in the given subband of the received image to decide whether the image is attacked maliciously or processed acceptably(the embedded wavelet compression) .The most important advantage of our watermarking scheme is that the watermark information can be extracted from the watermarked image when detecting watermark,so the received image authentication needs no information about the original image or watermark.Experimental results prove the effectiveness of our proposed watermarking scheme.展开更多
文摘在众多的图像压缩算法中,SPIHT和SPECK具有较好的性能,文中对这两种算法进行了深入地研究.首先介绍了小波变换后系数的分布特点,然后从算法思想、集合定义、分裂过程、排序过程、量化以及编码后的码流等方面分别介绍了SPIHT(Set Partitioning in H ierarchical Trees多级树集合分裂)和SPECK(Set Partitioning Embedded B lock Coder集合分裂嵌入块)算法,最后总结了他们的异同之处.
基金Supported by the National Natural Science Foundation of China (No. 90304003)the President Fund of GUCAS (No. O85101HM03).
文摘A new fractal image compression algorithm based on high frequency energy (HFE) partitioning andmatched domain block searching is presented to code synthetic aperture radar (SAR) imagery. In the hybridcoding algorithm, the original SAR image is decomposed to low frequency components and high frequencycomponents by wavelet transform (WT). Then the coder uses HFE of block to partition and searchthe matched domain block for each range block to code the low frequency components. For the high frequencycomponents, a modified embedded zero-tree wavelet coding algorithm is applied. Experiment resultsshow that the proposed coder obtains about 0. 3dB gain when compared to the traditional fractal coderbased on the quadtree partition. Moreover, the subjective visual quality of the reconstructed SAR imageof the proposed coder outperforms that of the traditional fractal coders in the same compression ratio(CR).
文摘In this paper, the authors propose a new approach to image compression based on the principle of Set Partitioning in Hierarchical Tree algorithm （SPIHT）. Our approach, the modified SPIHT （MSPIHT）, distributes entropy differently than SPIHT and also optimizes the coding. This approach can produce results that are a significant improvement on the Peak Signal-to-Noise Ratio （PSNR） and compression ratio obtained by SPIHT algorithm, without affecting the computing time. These results are also comparable with those obtained using the Embedded Zerotree Wavelet （EZW） and Joint Photographic Experts Group 2000 （JPG2） algorithms.
文摘A novel semi-fragile watermarking scheme for the content authentication of images using wavelet transform(WT) is presented in this paper.It is tolerant to the embedded wavelet image compression methods based on WT such as embedded zerotree wavelet(EZW) ,set partitioning in hierarchical trees(SPIHT) and embedded block coding with optimized truncation(EBCOT) in JPEG2000 to a pre-determined bit-plane,but is sensitive to all other malicious attacks.The image features are generated from the lowest-frequency(LF) subband of the original image as the embedded watermark.The watermark is embedded into the pre-determined bit-plane by adjusting the corresponding values in the given subband.In the process of watermarking authentication,we compare the image features generated from the LF subband of the received image with the embedded watermarking information(the image features of the original image) extracted from the pre-determined bit-plane in the given subband of the received image to decide whether the image is attacked maliciously or processed acceptably(the embedded wavelet compression) .The most important advantage of our watermarking scheme is that the watermark information can be extracted from the watermarked image when detecting watermark,so the received image authentication needs no information about the original image or watermark.Experimental results prove the effectiveness of our proposed watermarking scheme.
