Image-based Digital Watermark Technology

The rapid growth of the information technology,the development of e-commerence, the increasingly easy access to digital media, and the increasingly powerful digital media manipulation tools have made media secutity have been proposed. Information hiding and digital watermarking are new measures of digital media protection, which are processes of embedding hidden messages within digital media such as text,images, video and audio. The hidden messages could be copyright information, user distributor identification number, company logo, personal signature, control bits, or any information considered useful for a specific applicaton. 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 principls and characteristic of information hiding technique and watermarking technique, introduced the research backgrounds, basic principles, application areas, and resent 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 frequency of DCT transform. Last we have the conclusion: the algorihm based on DCT have strong robustness when experience attack, and we can extract it after that.3. Analyze the basic theory of wavelet packet and wavelet transform, point out the advantages of using wavelet transform in digital watermarking. Put forward a new kind of watermarking schemes in DWT based on mentally densest. Situation result of the algorithm show that the method have strong robustness when experience attack, and we can extract clear watermark after that.