Research On Authentication Watermark For Images Combined With The Protection Of Copyright

With the rapid development of computer network and communication technology, digital media (including digital images, digital video, and digital audio) has been widely used. Information security, intellectual property protection and certification issues on digital media become increasingly prominent. Image authentication technology is a technology as the need to determine the authenticity and integrity of images, is the effective means to ensure the storage and transmission of images in the internet age. It mainly solves two problems: one is to determine whether images are tampered, that is the distinction between alteration and normal processing; the other one is the location and restoration of tamper. At present, the methods for image authentication mainly include digital signature technology, which requires additional signature information, and digital watermarking technology, which authentication information is hided to the original images without additional information. Therefore, most of the image authentication methods use digital watermarking technology.In this paper, a number of meaningful explorations to authentication watermarking technology for images combined with the protection of copyright have been done. It can achieve the protection of copyright and the certification of images. The main points of work include the following:First, discussion of the image authentication methods based on the digital watermark, the analysis of the advantages and disadvantages of the main existing methods at home and abroad.Second, a compound watermarking scheme for image authentication is presented. It mainly uses the characteristics of wavelet decomposition in the spatial-frequency domain, the quadtree structures received by the wavelet decomposition and statistical information on the nodes to choose the location where to embed the watermark, and then adaptively change the wavelet value without affecting the image quality. The results show that the scheme has a higher ratio of signal to noise.Watermark can not only be extracted blindly, identify non-malicious tamper and malicious tamper, can also detect the distorted location of images with high accuracy.Third, a dual watermarking scheme for medical images authentication based on chaotic mapping and ROI is proposed, trying to apply chaotic mapping's initial value sensitivity to tamper detection. It mainly uses the characteristics of wavelet decomposition in the spatial-frequency domain, the quadtree structures received by the wavelet decomposition and statistical information on the nodes to choose the NROI location where to embed the robust watermark; The MOD function is used to design a mapping function defined on two separate blocks, and authentication watermark sequence, is produced by using Logistic chaotic mapping, is embedded into the corresponding mapping block of NROI. The results show that the distorted location of images can be detected, then be located and recovered. It can not only implement the authentication of medical images, but also the protection of copyright.