ISSN 1000-1239 CN 11-1777/TP

• 信息安全 •

### 双层差值扩展可逆数字水印算法

1. 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) (wgsu@gxu.edu.cn)
• 出版日期: 2019-07-01
• 基金资助:
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)

### Two-Layer Reversible Watermarking Algorithm Using Difference Expansion

Su Wengui1,2, Shen Yulong1, Wang Xiang3

1. 1(College of Computer Science and Technology, Xidian University, Xi’an 710071);2(Guangxi Key Laboratory of Manufacturing System & Advanced Manufacturing Technology (College of Mechanical Engineering, Guangxi University), Nanning 530004);3(College of Telecommunications Engineering, Xidian University, Xi’an 710071)
• Online: 2019-07-01

Abstract: 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 0.5bpp. 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 0.5bpp. Experimental results verify that the proposed algorithm provides higher embedding capacity while maintaining lower distortion in image quality.