In view of the limitation that most of the watermarking algorithms are single in functions and unable to achieve perfectly blind detection,a bifunctional watermarking algorithm with perfectly blind detection for copyright protection and content authentication was proposed.The algorithm adopted the idea of region segmentation for sub-block,and the generation and embedding of watermark were respectively carried out in the different regions of the same sub-block.A feature watermark was generated by judging the parity of the first digit from the average of maximum singular values,and the watermark was embedded by adjusting two DCT coefficients of adjacent blocks in the same position.Both the image copyright protection and content authentication functions were achieved by comparing the generated feature watermark and blindly extracting authentication watermark in the detection.Compared to some of the reported watermarking schemes,the proposed algorithm not only has better robustness against the common attacks to realize the copyright protection,but also has a good sensitivity to malicious image tampering to accurately locate the tampered area.%针对现有大部分水印算法功能单一且无法实现完全盲检测的局限性,提出一种同时进行版权保护和内容认证的全盲双功能数字水印算法.算法采取子块区域分割的思想,水印产生和嵌入分别利用同一个子块的不同区域.通过判别两个最大奇异值均值的最高位奇偶性产生特征水印,然后自适应地调整相邻区域相同位置的两个离散余弦变换交流系数的大小,实现水印的嵌入.检测端通过产生的特征水印和盲提取的认证水印实现全盲的版权鉴别和内容认证.相比于已报道的一些水印方案,本文提出的水印算法对于常见的攻击具有更好的顽健性,可以实现版权保护功能,同时对于恶意的图像篡改又有较好的敏感性,可以准确定位篡改的区域.
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