基于置乱和混沌加密的DCT域公开水印技术研究

目前有很多基于离散余弦变换(DCT)的水印算法,但很少讨论到公开水印传播的安全性问题.为进一步增强水印系统的安全性,文中将嵌入的水印信息进行置乱和混沌加密处理,然后选择中频系数为嵌入水印的位置.实验结果表明,该公开水印算法除了能较好地保证水印的安全性外,对图像剪切、中值滤波、JPEG压缩和噪声干扰等常见图像处理操作有较高的鲁棒性.同时,嵌入水印具有很好的透明性,水印的提取无须求助于原图像.

Public Watermarking Technique Based on Scrambling Transformation and Chaotic Encryption in DCT Domain

Though many DCT - based watermarking algorithms have been presented, few of them discuss the issue of which method is better to improve the security of the watermark. In this paper, to further enhance the security of the watermarking system and make the watermark be hard to be extracted, the watermark is scrambled and chaotically encrypted before embedded into the original image, then the watermark is embedded into the parts of medium frequency coefficients. The experimental results show that the introduced algorithm is effective and robust for common image processing such as cropping, median filtering, JEPG compression and blurring noise added etc. besides its good security. The embedded watermark is invisible to human eyes and its extraction without the need of the original image.