The Research On Image Protection Technology Based On Perceptual Hashing

This thesis briefly introduces the study backgrounds and research status of Perception Image Hash at home and abroad and makes further studies on the methods with illustrating on the extraction process of characteristics in system. Then, we compare and study the characteristics extraction methods of Wavelet Transform and Discrete Cosine Transform, and select Discrete Cosine Transform as the characteristics extraction method combined with the characteristics of multimedia information.We use the Non-negative Matrix Factorization to decompose the image matrixes and keep the Coefficient Matrix as data that needs post treatment, which will not only improve the computational efficiency but also reduce the storage space effectively. The experiment shows that the method has good robustness and retrievement through using Discrete Cosine Transform to extract characteristics and using human visual model to process coefficient and encrypting with Chaotic Sequence.Generally, the Hash Algorithm using Discrete Cosine Transform to extract characteristics could not resist geometric attack. In order to improve the robustness of this calculation method, we introduce the concepts of Zernike moments and use its rotation invariance to extract the moment from Image Matrix to generate hash sequence which is added into Perceptual Hash sequence as Characteristics of test sequences to against geometric attacks. This article extracts the first ten steps of image as we called Zernike moments to generate hash sequence and use Matlab to make experimental verification. The results show that the method has improved the robustness effectively and could resist the image rotation attack.In this paper, the image encryption techniques of chaos theory are researched. The image protection technology not only has to protect Robustness of image but also has strong safety, so it is especially important to encrypt image. Combined with the characteristics of multimedia information encryption and made full use of the characteristics of chaos theory, we put forward a method that uses Chaos Theory to encrypt each stage of hash image which can not only satisfy the safety requirements of Hash Algorithm but also has good flexibility and anti-attack capabilityPerceptual hashing technology as an emerging technology will play an increasingly important role in multimedia management. The core of Perceptual Hashing technology has been used as a basis and it combines efficiently Perceptual Hashing technology with the Chaos Theory and Non-negative Matrix Factorization and human vision model. It improves existed hash Extraction Algorithm and has a great role in promoting image protection technology.