A kind of nonsubsampled contourlet and block-based cosine transform(NSCBCT)is developed,and its application in image fusion is studied in this paper.The construction of filtering banks is based on the nonsubsampled co...A kind of nonsubsampled contourlet and block-based cosine transform(NSCBCT)is developed,and its application in image fusion is studied in this paper.The construction of filtering banks is based on the nonsubsampled contourlet transform(NSCT)and block-based discrete cosine transform(B-DCT).We combine NSCT and B-DCT to design filters that lead to NSCBCT with better singularity representation than either of them in isolation.A design framework based on the hybrid approach is proposed,which allows for the fast implementation based on NSCT and B-DCT respectively.In addition,a new image fusion scheme based on NSCBCT for multispectral and panchromatic satellite images is proposed.Firstly,because it adopts NSCT,the fused satellite images have higher spatial resolution than those based on wavelets.Secondly,based on the localized high frequency information provided by B-DCT,the proposed fusion scheme can reduce the spectral distortion of the fused image further.Experimental results show that the proposed fusion method is able to increase the spatial resolution and reduce the spectral distortion of the fused image at the same time.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
文摘提出了一种改进的 L ZC(listless zerotree coding)图像编码算法 ,该算法不仅继承了原有 L ZC算法不使用链表、易于硬件实现的优点 ,而且针对原始算法子带扫描顺序不尽合理、递归结构算法复杂度较高等缺点 ,通过改变空间子带的编码顺序 ,将块的概念引入编码过程在改进算法中完全采用顺序结构等措施进一步提高了原有算法的工作效率、降低了 L ZC算法的复杂度。实验结果表明 ,该算法是一种高效的图像编码算法 ,其不仅具有良好的视觉效果、无方块效应 ,而且在相同压缩比情况下 ,该算法的图像重构质量和 PSNR均明显优于原始的 L
文摘A kind of nonsubsampled contourlet and block-based cosine transform(NSCBCT)is developed,and its application in image fusion is studied in this paper.The construction of filtering banks is based on the nonsubsampled contourlet transform(NSCT)and block-based discrete cosine transform(B-DCT).We combine NSCT and B-DCT to design filters that lead to NSCBCT with better singularity representation than either of them in isolation.A design framework based on the hybrid approach is proposed,which allows for the fast implementation based on NSCT and B-DCT respectively.In addition,a new image fusion scheme based on NSCBCT for multispectral and panchromatic satellite images is proposed.Firstly,because it adopts NSCT,the fused satellite images have higher spatial resolution than those based on wavelets.Secondly,based on the localized high frequency information provided by B-DCT,the proposed fusion scheme can reduce the spectral distortion of the fused image further.Experimental results show that the proposed fusion method is able to increase the spatial resolution and reduce the spectral distortion of the fused image at the same time.
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.
