The Research On Chinese Text Digital Watermarking Technology Based On Sine Wave

With the wide spread use of the Internet in our society, the distribution and access of information is greatly facilitated. However, without effective methods which can prevent illicit redistribution and reproduction of information content, copyright can be easily infringed. Digital watermarking is widely believed to be a valid solution to the problem. Currently, there is intensive research in this area. However, compared to the plurality of previously proposed methods in digital watermarking for picture, audio and video, digital watermarking methods for text documents are very limited. One reason for this difference is the special features of text documents structure. Moreover, Chinese is differing with English in both spatial characteristic and semantics, thus we should present corresponding watermarking methods of Chinese text document according to its characteristic.This paper performs an in-depth research on Chinese digital text watermarking in different application fields, which is based on the sine wave theory. On the one hand, the idea of watermarking is used by slightly adjusting text format, which changes the grayscale of characters by sine function; on the other hand, the algorithm considers the structure of Chinese document and information of Chinese character during the embedding. The study can be concluded into three aspects: Firstly, a scheme for document authentication is proposed, which can ensure the authenticity and integrity of text. The method segments the original document into paragraphs and determines the parameters of sine wave by the characteristic of related text block. Then the watermark can be embedded. After the modification, the alteration of the grayscale shows characteristics of corresponding sine wave; next, a scheme for copyright marking is proposed, which embeds the copyright information into the text document to provide protection. The method encrypts the copyright information into binary sequence for repeated embedding and the intensity of watermarking can be set by the user. At the same time, it introduces the binary-tree theory of Chinese Mathematical Expression during the random embedding to improve the robustness of watermarking. The alterations of grayscale is also controlled by sine wave, which can divide the mark into several segments and reduce the error rate in the detection; lastly, a scheme for distribution control is proposed, which can prevent unauthorized document copy and trace the unlawful user. The method generates a random sequence to identify the original recipient of the document by user register. Then it uses the CRC error coding technique to form a watermark sequence. Only characters which rank first 1000 in the...