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
文摘针对采用最大体积单体MVS(Maximization Volume Simplex)端元提取算法进行端元初选时存在相似端元光谱问题,提出一种光谱信息散度SID(Spectral Information Divergence)和光谱梯度角SGA(Spectral Gradient Angle)相结合以区分两个相似端元光谱的方法。该方法对经过端元初选之后的端元子集进行端元的二次选择,采用以SID_SG作为最相似端元选择的判据,除去相似端元,降低相似端元对解混精度的影响,利用全约束最小二乘法进行丰度估计。实验结果表明,提出的优化方法与传统方法相比,提高了端元的选择精度,重构影像与原始影像之间的均方根误差RMSE(Root Mean Square Error)也有所降低,分布更加均匀。该方法对高光谱遥感影像进行深度解译具有十分重要的意义。
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.
