一种DWT和DCT相结合的数字图像水印算法

A digital image watermarking algorithm based on the combination of the DWT and the DCT

提出一种DWT变换和DCT变换相结合的灰度图像数字水印算法。对二值水印图像进行置乱和混沌加密处理,将水印图像序列调制成正负序列。在水印的嵌入过程中,对载体图像进行小波变换,提取出其低频系数矩阵,将低频系数矩阵划分成4×4大小的子块,针对各子块进行DCT变换,采用正负量化的方法进行水印的嵌入。实验结果表明,该算法对JPEG压缩、加噪、剪切和滤波等攻击,具有良好的抵抗能力,鲁棒性较好。

An algorithm for the gray-scale image digital watermarking was proposed by combination of the DWT and DCT transformation.First,scrambling and chaos the binary watermark image and then modulate a sequence of watermark image into a sequence of positive and negative.In the watermark embedding process,we perform wavelet transform to the image and extract the low-frequency coefficient matrix of it,then the low-frequency coefficient matrix is divided into 4×4 sub-block,with each sub-block being transformed with DCT,and the positive and negative methods has been used to quantify the embedded watermark.The experimental results show that the algorithm has a good resistance and better robustness for attacking the JPEG compression,plus noise,shear,filtering and so on.