基于混沌理论和量化方法的双功能水印算法

针对传统数字水印功能单一的问题,提出一种同时实现版权保护和完整性认证的双功能水印算法。采取块均值量化方式,使水印嵌人过程中块内系数的变化值自适应于系数本身大小,以协调不可见性与鲁棒性,同时利用混沌映射构造与图像特征信息相关联的认证水印嵌入图像的最低有效位,以减少脆弱水印对鲁棒水印的影响。实验结果表明,该算法中的鲁棒水印对常见攻击具有抗攻击性,脆弱水印具有敏感性,且能定位出图像的篡改位置。

Bifunctional watermarking algorithm based on chaos theory and quantitative methods

Due to the monotonicity of the traditional digital watermarking function,a bifunctional watermarking algorithm is proposed to achieve both copyright protection and certification integrity.Block coefficients variation value is adapted to the size of coefficients itself through block quantization to coordinate invisibility and robustness while embedding watermark at the same time.Using the chaotic mapping,authentication watermark associated with the image feature information can be embedded in the least significant bit of the image to reduce effects of fragile watermark on the robust watermark.Experimental results show that the robust watermark by this algorithm is anti-aggressive to common attacks,the fragile watermark has good sensitivity,and the tampering position of the image can also be well positioned.