Research On Image Tapmer Localization And Copyright Protection Based On Digital Watermarking

With the development of computer network and multimedia technology, it ismore convenient to distribute digital products. However, this will lead to more issuesof piracy and information tamper for some interests. As one of the importantapplications of information hiding technology in computer field, digital watermarkingprovides a new method to protect the copyright and integrity of multimediainformation through embedding extra information. Based on the projects granted byNational Natural Science Foundation, we study on the watermarking schemes focusedon copyright protection and tampering localization. The main contributions of thisdissertation are as following:1. Image authentication schemes based on digital watermarkingA one-way Hash function based on the chaos was proposed. Since thesignificance of Hash function, we proposed a one-way Hash function based on achaos system. The detailed analysis was performed, which presents the proposedone-way Hash function possesses good performances of anti-attack and diffusion. Thesimulation shows the effectiveness and validity of our algorithm in variousconditions.An authentication scheme for JPEG image was proposed. The JPEGcompression and JPEG compression invariance were introduced firstly. Then anauthentication scheme for JPEG image was introduced based on the one-way Hashfunction and JPEG compression invariance. The experiments show that the proposedscheme could enhance the perceptual quality of watermarked image and localize thetampering correctively.A fragile image authentication scheme with the capabilities of accurate tamperlocalization and tamper recovery was proposed. The watermarks, includingauthentication code and recovery code, were coded with BCH and embedded into theLSB of the image. Next, we analyzed the capability of tamper localization andfulfilled the process of tamper localization and recovery. The experiments show thatour scheme enhanced the accuracy of tamper localization and maintained a goodability of image recovery when tamper ratio is smaller than7%. 2. Copyright protection schemes based on digital watermarkingA robust watermarking scheme based on neural network was proposed. Thewatermark and some extra information were embedded into all three imagecomponents together. Three BP networks were trained by extra information and thenused to predict the embedding data. All predictive result voted according to theirweight to get the watermark representing the owner’s copyright. Since watermarkingembedded in different components, the perpetual quality of watermarked image andthe robustness of our scheme were both better than existed schemes.A robust lossless watermarking scheme was presented based on block gravitycenter shifting. Two classic previous schemes were introduced and then theirweaknesses were analyzed. According to the feature, we demonstrated the similaritybetween gravity centers of different blocks derived from low frequency band in DWTdomain. According to the shifting of pairs of gravity centers, the proposed scheme isnot only lossless but also maintains the ability of discriminating malicious tamper andoccasional tamper.