Research On Algorithm For Improving The Stealthiness Of Watermarking

With the rapid development and extensive use of communications technology and network technology, digital multimedia information storage, reproduction and dissemination has become very convenient, so, copyright protection of digital products become urgent problem, and information hiding emerges in such circumstances. Digital watermarking technique is one of the main branches of the information hiding technology, and it is a new and effective means of copyright protection。In recent years, Digital watermarking technique become one of the most hotspots in the filed of multimedia security.Images, sound and so on as the multimedia information has a large number of redundant information, the existence of these redundant information makes the image or sound can hide some information, and will not give rise to the doubts of the observer. But, the text signal does not have the redundant information. A bit of text changes, the errors will happened in the text. So the methods of the watermark embedding in the text are different to the methods in the images or sound signal. No matter what the cover object and any of embedding algorithm, the region of embedment is very important, and it relates to the stealthiness of the watermarking algorithm. If the region of embedment is the right choices, we can better hide watermark, and make the attacker difficult to find it, so, it can reduce the success rate of attacks.This paper presents a new protocol based the hierarchical model which can improve the stealthiness of the digital watermarking algorithm. The protocol can be used in combination to the watermarking algorithm of the images,sound,text and so on to determine the region of the embedment, hereby, the stealthiness of the watermarking algorithm can be improved. In this paper, the selective cover object is the text file of the form of natural language, and the embedding watermark is the same form to the cover object. The selective watermarking algorithm is the feature coding algorithm of the text watermark. Based on the theoretical analysis, this paper has the simulative experiment to verify the protocol.