基于DCT域的自适应数字水印算法

针对离散余弦变换(DCT)的特点,提出一种自适应水印算法.选取JPEG量化矩阵若干DCT中频系数,并求均值,比较嵌入位与均值的关系,调整嵌入位的大小实现水印自适应嵌入.利用Arnold变换对水印信息进行预处理和后续处理,降低水印信息的相关性;同时用随机控制方法选取水印嵌入图像块,用于控制随机选取块的密钥作为该算法的一个密钥,实现水印的加密处理,提高水印的安全性.实验表明,该算法在保证隐蔽性的前提下,水印提取效果较好,对旋转、剪切、JPEG、修改等攻击具有较好的鲁棒性和稳健性.

Adaptive digital watermarking algorithm based on DCT domain

Aiming at the characteristics of Discrete Cosine transformation to propose an adaptive digital watermarking algorithm was proposed,Some medium frequency DCT coefficients with JPEG matrix were selected and their mean was calculated,and after comparing the mean with the embedded coefficient,watermarking embedded adaptively was achieved by adjusting the value of embedded coefficient.The pretveatment and subsequent treatment on watermarking were conducted by Arnold transformation to reduce the relativity among watermarking dates.Embedded image blocks were chose randomly with a key,and the key was regarded as a key of the algorithm to achieve watermarking encrypted and improve the security of the algorithm.The experiment shows that the algorithm has a good effect on extracted watermarking,enough robustness and toughness for some common image processing operations,such as rotation,cutting,JPEG compression,altering,etc.