基于混沌置乱离散余弦变换的图像水印研究

Study on Image Watermarking Algorithm Based on Chaotic Scrambling DCT

关于数字水印优化版权保护技术,研究优化图像水印问题,要求不被复制和抗攻击性。传统的离散余弦变换的图像水印算法,水印信息均分布于整个图像,当含水印图像遭到攻击后,提取的水印图像有明显失真。为消除失真,改善水印提取效果,提出了混沌置乱离散余弦变换的图像水印算法。在传统的离散余弦变换(DCT)数字水印算法的基础上,引入了混沌理论。利用了混沌理论,获得混沌序列具有对初始值的不可预测性能和高度的敏感性,所以特别适合作为置乱地址发生的特点,获得一个置乱网络,然后将水印信号进行加密处理,增加抗几何破译的能力。实验结果表明,改进的算法保持了鲁棒性和不可见性,同时也消除了失真,获得了很好的图像水印提取效果。

Because the watermark information is distributed in the whole image,great distortion and black thin line exist around the main diagonal pixels while employing a conventional DCT-based method for extracting and recovering the watermark from the cover image which is attacked.In order to solve the above problem,a novel image watermarking algorithm based on DCT in wavelet domain is presented in this paper.Firstly,a special meaningful binary image should be constructed and the text information is set in the lower left and upper right corner of the image.In that there is no text information around the main diagonal pixels.A good result can be obtained when we extract and recover the watermark by means of simple computing.Experimental results indicate that the proposed algorithm is invisible and robust and also eliminates the distortion.Finally,a good watermark extraction is obtained and the algorithm can be employed for copyright protection.