一种二维混沌加密彩色图像自适应水印算法

Color Image Watermarking Algorithm Based on Two Dimension Chaotic Encryption

数字水印技术可以有效地保护数字产品的版权,维护数据安全。现有的数字水印方法大多数针对灰度图像,而较少研究彩色图像。但是与灰度图像水印相比,彩色图像水印含有更多的信息。因此,文中提出了一种二维混沌加密的彩色图像自适应水印算法。经过二维logistic混沌迭代生成加密水印。在水印嵌人过程中,把彩色图像亮度分量分成互不重叠的图像块,用分数盒维数分析各块的特征,提取特征块和次特征块,对它们分别进行一级小波分解,先将水印以不同强度自适应地嵌入到特征块的小波域低频子图中,在保证隐蔽性的前提下,再次将水印以不同强度自适应地嵌入到次特征块的小波域低频子图中。实验结果表明,该算法对JPEG压缩、加噪、剪切、滤波等具有较强的稳健性。

Digitalwatermark technique is effective in protecting copyright of digital products and maintaining data security. Existing digital watermarking algorithms are mostly designed against gray images but few are for the color images. This paper presents a color image watermarking algorithm based on two dimension chaos encryption. Use the two dimension logistic chaotic map to generate the watermark. An original image is divided into non-overlapped blocks,fractional boxcounting dimension is used to analyze the feature of the image blocks to extract the feature blocks and secondary feature blocks and then used one level DWT to decompose them. The different strength watermark is adaptively embedded into the low-frequency coefficients of the feature blocks,under the condition that the watermark embedded is invisibh,and then is embedded into the secondary feature blocks in the same way when embedded watermarking. Experimental results demonstrate that the watermarking scheme is strongly robust to different types of attacks such as JPEG compression,noise addition,eropping, filtering and so on.