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
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.
文摘目的为了提高数字水印的鲁棒性和不可见性,提出一种基于Laplacian Pyramid和LWT-QR分解的水印算法。方法首先对宿主图像进行2层Laplacian Pyramid分解,取其第2层Laplacian残差图像进行一层LWT分解,取其低频子带进行大小为4×4的无重叠分块处理。然后,基于提升小波系数的相关属性,再对每个选中的低频子块进行QR分解,取分解后R矩阵的第1行为目标进行水印的嵌入,同时对水印进行Arnold置乱,置乱后的水印图像嵌入到R矩阵的第1行元素中。结果嵌入水印后图像的PSNR能够达到45 d B,而且该方案对常见的信号处理攻击有较好的鲁棒性,NC均值在0.9以上。结论理论分析和大量的实验数据表明,该方案能够很好地改善图像操作过程中的鲁棒性和不可见性。
