Based On Image Content Semi-fragile Watermarking Technology

Along with the fast development of the multimedia technology and computer network, more and more digital products are being transmitted through the internet. While bringing great convenience to people's life, it also cause illegal copy and malicious tempering. Digital watermarking in accordance with its characteristics can be divided into robust watermark and the vulnerability of the two watermark, the watermark both have their advantages and disadvantages. In this paper the advantages of two watermarking, focuses on the one in between semi-fragile watermarking technology.In this paper, the development of digital watermarking status at home and abroad, and then a digital watermark on the basic principles and relevant theoretical knowledge, and then analyzed the contents of several image-based digital watermarking algorithms, on an issue such as the use of wavelet Transform, HVS human visual system, semi-fragile watermarking technology, and other aspects of the theoretical foundation of knowledge. Finally reference and comprehensive information on various aspects of the study, which is based on image content Semi-fragile watermarking algorithm. This algorithm will be the original images wavelet transform, its approximation of wavelet transform coefficient using pseudo-random sequence modulation resulting in the formation of the content-based image watermark signal. Wavelet transform has good air-frequency characteristics, but also a good match human visual system, but also with the new JPEG2000 standard compatible. Papers completed the watermark embedded in it after the attacks of the anti-testing, to determine how to tamper with the regional and tampering with the type of semi-fragile watermarking method. Simulation experiments show that the algorithm has good robustness and identification were tampered with regional capacity.