双层差值扩展可逆数字水印算法  

Two-Layer Reversible Watermarking Algorithm Using Difference Expansion

作　　者：苏文桂 沈玉龙[1] 王祥[3] Su Wengui;Shen Yulong;Wang Xiang(College of Computer Science and Technology, Xidian University, Xi’an 710071;Guangxi Key Laboratory of Manufacturing System & Advanced Manufacturing Technology (College of Mechanical Engineering, Guangxi University), Nanning 530004;College of Telecommunications Engineering, Xidian University, Xi’an 710071)

机构地区：[1]西安电子科技大学计算机科学与技术学院,西安710071 [2]广西制造系统与先进制造技术重点实验室(广西大学机械工程学院),南宁530004 [3]西安电子科技大学通信工程学院,西安710071

出　　处：《计算机研究与发展》2019年第7期1498-1505,共8页Journal of Computer Research and Development

基　　金：陕西省重点研发计划项目(2017ZDXM-GY-014);广西制造系统与先进制造技术重点实验室基金项目(17-259-05S007)~~

摘　　要：传统的差值扩展可逆数字水印算法通过将图像相邻像素对的差值进行扩展来嵌入1 b水印,最大嵌入率为0.5 bpp.其不足之处在于低嵌入率和高嵌入失真.为提高嵌入率,差值扩展算法需进行多次嵌入,由于无法有效地利用像素间的相关性,从而带来较大的嵌入失真.为了提高嵌入性能提出一种新的双层差值扩展嵌入可逆数字水印算法,通过分析差值扩展对像素对的修改规律,对第1层嵌入和第2层嵌入分别采用不同的像素对构建方式,更好地利了像素的相关性,并进一步利用像素块的均值作为预测器优先选择平滑像素对用于嵌入,使得在超过0.5 bpp的嵌入率时仍可保持较高的峰值信噪比.仿真实验结果表明:所提出的算法在提高水印嵌入容量的同时可有效减少图像的失真.Traditional difference expansion algorithm expands the difference between two adjacent pixels and embeds one bit of secret data to the expanded difference of the pixels of each pair if no overflow or underflow occurs. It can achieve an embedding rate up to 0.5 bpp. The shortcoming of this algorithm is that it cannot provide higher embedding rate while keeping distortion low. To achieve higher capability, multiple-layer embedding is required for traditional difference expansion reversible watermarking. However, repetitive embedding of images in the same way does not effectively exploit the characteristics of difference expansion and the correlation among pixels, which will result in large image distortion. To achieve better capacity and superior performance, a novel difference expansion-based algorithm which enables two-layer embedding and pixel pair selection is proposed. The cover image is firstly divided into pairs of pixels. By analyzing the modification mechanism of pixel pairs in difference expansion, a different paring manner for each embedding is developed to better exploit the correlation among different pixel pairs. Furthermore, the mean of pixel pair is utilized as a predictor to select smooth pixel pairs for embedding, so that a higher peak signal-to-noise ratio can be achieved even when the embedding rate exceeds 0.5 bpp. Experimental results verify that the proposed algorithm provides higher embedding capacity while maintaining lower distortion in image quality.

关 键 词：差值扩展 可逆水印 信息隐藏 双层嵌入法 像素选择 

分 类 号：TP391[自动化与计算机技术—计算机应用技术]