The Study Of Fragile And Semi-fragile Digital Watermarking Technique For Digital Image Authentication

As an effective means of a protection of the intelligent property right for the digitalproducts, the digital watermarking technique got the extensive concern, and has become theinternational research focus in the academic circles. Based on the research with the digitalwatermarking technique particularly the authentication watermarking technique,the thesis putforward two kinds of digital watermarking projects of the integrated authentication of digitalimage:fragele and semi-fragile digital watermarking and pointed out its limits throughanalysis of current typical model calculation ways home and abroad from different angles. Onthis foundation, we attempted to build up a fragile watermarking algorithm according to thechaos system and a semi-fragile watermarking algorithm according to the imvariant propertyto JPEG lossy compression, carried out the analysis to its experiment and proved therationality of this algorithm. This research will be beneficial to the promotion and applicationof the digital watermarking technique.First of all, we investigated the digital watermarking theories systematically, summarizedthe general theory and general models of the digital watermarking, pointed out its mainforeground of application and analyzed typical algorithm of various kinds and main attackmethod of the digital watermarking. Fragile and semi-fragile digital watermarking techniqueswere analyzed in detail. In addition, we summarized the basic frame of it and relatedrequirements of the two algorithms and discussed the recent development of the two kinds ofwatermarking techniques systematically in the last few years and analyzed the attack behaviorto the watermarking at integrated authentication that the authentication watermarking besubjected to.In the nest place, we put forward a fragile digital watermarking algorithm, which canovercome the restrictions of the characteristics of its own and can, at the same time,Strengthen the relationships among all blocks. The experimental results have demonstratedthat this algorithm can locate the tampered area as well as detecting "collage-attack" to thewatermarked image.This paper we also put forward an algorithm for semi-fragile watermarking of still imageaccording to the invariant property to JPEG lossy compression and based on the invariantproperty to JPEG of the coefficient of DCT, which enables the blind examination.Moreoverthis algorithm obtains the good balance in the robustness and fragility-the algorithm has the very strong robustness to the non- malicious attacks and the good ability in the identificationand position to the malicious attacks.Last, the thesis carried out a summary of the possible research direction of digitalwatermarking technique and pointed out further academic direction.