基于混沌的DCT变换域数字水印算法

Watermarking Algorithm Based on Chaotic System and Discrete Cosine Transform Domains

该算法一方面利用强混沌系统理论中的环形自同构系统对作为水印信息的二值图像进行置乱,另一方面对载体的灰度图像进行分块DCT变换,之后用JPEG标准中的较大压缩率情况下的量化矩阵量化DCT系数。用量化后不为零的DCT系数的统计特征来实现置乱后的水印信息的嵌入。结果表明,该算法较好地解决了鲁棒性(特别对JPEG压缩)和视觉不可见性。

This paper proposes a image-based watermarking algorithm,which embeds a binary image as the watermark.Adapting Toral Automorphism system,which belong to theory of Strong Chaotic System,firstly,the watermarking algorithm disorders the binary image used as the watermark.Then the algorithm carries out discrete cosine transform on the blocks of a gay scale image used as the carrier of watermark and then uses quantization matrix depicted in JPEG standards,which are used when a image needs a relatively high compression rate,to quantize the DCT coefficients.After the quantizing of the DCT coefficients,some statistical characteristics of the coefficients which are still not equal to zero will be used to implement the embedding of the watermark.Given the embedding course of watermark mentioned above,this watermarking algorithm is expected to have great robustness,specially to JPEG compressing,and watermark embedded through this watermarking algorithm be invisible.