In order to protect copyright of digital images,a new robust digital image watermarking algorithm based on chaotic system and QR factorization was proposed.The host images were firstly divided into blocks with same si...In order to protect copyright of digital images,a new robust digital image watermarking algorithm based on chaotic system and QR factorization was proposed.The host images were firstly divided into blocks with same size,then QR factorization was performed on each block.Pseudorandom circular chain(PCC) generated by logistic mapping(LM) was applied to select the embedding blocks for enhancing the security of the scheme.The first column coefficients in Q matrix of chosen blocks were modified to embed watermarks without causing noticeable artifacts.Watermark extraction procedure was performed without the original cover image.The experimental results demonstrate that the watermarked images have good visual quality and this scheme is better than the existing techniques,especially when the image is attacked by cropping,noise pollution and so on.Analysis and discussion on robustness and security issues were also presented.展开更多
The Bi-LS method based on QR decomposition provides a convenient framework for de-veloping efficient subspace tracking algorithms.To overcome the shortcoming of the backsubstitution step and improve the parallel archi...The Bi-LS method based on QR decomposition provides a convenient framework for de-veloping efficient subspace tracking algorithms.To overcome the shortcoming of the backsubstitution step and improve the parallel architecture of the Bi-LS algorithms,a Bi-LS subspace tracking algorithm based on Inverse QR(IQR) decomposition is developed.The proposed IQR iterative algorithm for subspace tracking is well suited for the parallel implementation in the systolic array.Simulation results are presented to illustrate the effectiveness of the proposed IQR subspace tracking algorithm.展开更多
基金Project(2007AA01Z241-2) supported by the National High-tech Research and Development Program of ChinaProject(2006XM002) supported by Beijing Jiaotong University Science Foundation,ChinaProject(0910KYZY55) supported by the Fundamental Research Funds for the Central University in China
文摘In order to protect copyright of digital images,a new robust digital image watermarking algorithm based on chaotic system and QR factorization was proposed.The host images were firstly divided into blocks with same size,then QR factorization was performed on each block.Pseudorandom circular chain(PCC) generated by logistic mapping(LM) was applied to select the embedding blocks for enhancing the security of the scheme.The first column coefficients in Q matrix of chosen blocks were modified to embed watermarks without causing noticeable artifacts.Watermark extraction procedure was performed without the original cover image.The experimental results demonstrate that the watermarked images have good visual quality and this scheme is better than the existing techniques,especially when the image is attacked by cropping,noise pollution and so on.Analysis and discussion on robustness and security issues were also presented.
基金Supported in part by the 973 Program (No.2008CB-317109)the National Natural Science Foundation of China (No.60572054)the SRF for ROCS, SEM
文摘The Bi-LS method based on QR decomposition provides a convenient framework for de-veloping efficient subspace tracking algorithms.To overcome the shortcoming of the backsubstitution step and improve the parallel architecture of the Bi-LS algorithms,a Bi-LS subspace tracking algorithm based on Inverse QR(IQR) decomposition is developed.The proposed IQR iterative algorithm for subspace tracking is well suited for the parallel implementation in the systolic array.Simulation results are presented to illustrate the effectiveness of the proposed IQR subspace tracking algorithm.
