Print-and-photocopy Resilient Text Watermarking based on Hadamard Transform
In this paper, a novel watermarking algorithm is proposed for copy tracking of paper-based text documents. By modifying AC coefficients, the watermark is modulated and extracted in the transform domain of Hadamard transform, which is applied on the numbers of black pixels in each character of the binary text image. Meanwhile, by tuning DC coefficient, the distortion of each text character can be well controlled. The Hadamard transform is chosen based on the observation that their AC coefficients are less sensitive to print-and-photocopy. The novel algorithm can embed adequate data into office-like text document while keeping visual appearance, and resist printand- photocopy attack as well. Practically, by this method, we can embed identity information into electronic text files. When obtaining a paper-based illegal copy, we can restore it into electronic format by scanner and extract the embedded data through watermark decoding, then identify the source of the copy. This can improve the management of confidential files. The validity of our method is demonstrated via extensive experiments.
Xiaolong Li Bin Yang Wenfa Qi
Institute of Computer Science and Technology, Peking University, Beijing 100871
国际会议
2011亚太信号与信息处理协会年度峰会(APSIPAASC 2011)
西安
英文
1-9
2011-10-18（万方平台首次上网日期，不代表论文的发表时间）