基于双混沌系统的抗JPEG压缩的图像认证水印算法

提出了一种新的兼具水印高安全性和高定位精度的抗JPEG压缩的图像认证水印算法.根据JPEG图像压缩过程中DCT系数的不变特性,将预先量化的DCT低频系数和水印密钥合成为混沌系统的初值.再将图像块的编号映射为混沌系统的迭代次数,经过logistic混沌迭代生成图像块水印.在水印嵌入过程中,利用另一混沌系统猫映射构造循环结构,建立图像块之间一一对应的循环关系,并将块水印嵌入到对应图像块的DCT中频系数中.实验结果表明,该算法对JPEG有损压缩具有良好的鲁棒性,同时可对图像内容的恶意篡改进行精确的检测与定位.

Semi-fragile watermarking method for JPEG image authentication based on double chaotic maps

A novel semi-fragile image watermarking technique that accepts JPEG lossy compression was developed with improved security and localization aecuracy. According to the invariant properties of DCT coefficients before and after JPEG compressions,the pre- quantified low DCT coefficients and a watermarking key are combined as the initial value of chaotic system. The indices of image blocks are mapped into the iteration times of logistic map for generating the watermark. Then the watermark of each image block is embed into the middle DCT coefficients of the corresponding image block which is determined by the circular structure built by eat mapping. Experi- mental results showed that the proposed technique was robust against JPEG lossy compression,but sensitive to the malicious attacks on the watermarked image. At meantime,it can localize the tampers correctly and accurately.