Image-based Digital Watermark Technology

With the rapid development of computer and network, the daily life and work of human beings are becoming digitalized and networked. A large number of private data are transformed in the Internet, and electrical commerce is more and more popular. All these challenge the traditional method of copyright protection and technology of data security. In this background, digital watermarking is developed gradually. Digital watermarking technique is an a effective protection technique ,Which embeds a copyright information into multimedia products in order to authenticate the ownership or transmit to the available information. Based on the research and work of pre-scholars, regarding the situation of nowadays digital watermarking, so the main innovative work is done in this dissertation and is listed as follows:1. Design the program of watermark embed and extract ,investigate the basic principles and characteristic of information hiding technique and digital watermarking technique , introduced the research backgrounds, basic principles, application areas ,and recent development and the future of the digital watermarking technology ,do some program design on the bases of the research of the typical watermark algorithms.2. Discuss a digital watermarking technique based on the protection of the copyright of digital image from the invisibleness and robustness. First analyze the possible attack in the field of image circulation , Then make sure to add the watermark in the low and middle frequency of DCT transform. Last and we have the conclusion : the algorithm based on DCT have strong robustness when experience attack, and we can extract it after that.3. Analyze the algorithm of Mallat and the concept , characteristic of wavelet transform and wavelet packet, point out the advantages of using wavelet transform in digital watermarking and multi-resolution analysis . Put forward a new kind of watermarking schemes in DWT domain and test the algorithm. Simulation results of the algorithm show that the method have strong robustness when experience attack, and we can extract clear watermark after that.