Anti Jpeg Compressed Image Tamper Detection And Recovery

Digital watermarking is a technique for embedding a secret signal (watermark) into a host media in an imperceptible fashion, aiming to protect the copyright and content authentication. Digital watermarking has a high demanding prospect on copyright protection, integrity verification, data tracing, commercial VOD.On account of the inter-cross and the broadness of contents about the digital watermarking,aiming at one branch of the digital watermark,namely the semi-fragile watermarking, as well as combining the actual situation that at present the popular JPEG–format image is easily exposed to the malicious tampering like"exchanging two heads of two people",this paper puts a emphasis on the checking and recovering about the image tampering on the basis of resisting the JPEG compression in order to authenticate the content integrality of watermarked image and restore the image area which is tampered as adequately as possible.This article has made a few efficient innovation in the aspects as follows,compared with a great many of present semi-fragile watermark literature,getting satisfying experiment results:(1)On the basis of resisting the JPEG compression,attempting to combine the tamper check and restoration and the latter is implemented on the basis of the former;(2)Achieving the blind check to tampering and the orientation effects is excellent because of embedding two kinds of watermark which are both able to resist JPEG compression in the original image;(3)Excepting for tampering check and restoration of gray image,the tampering check and restoration of color image is also analyzed by experiments and it is found that the analyzation for color image is absolutely not so sample like decomposating it into R,G,B or Y,Cb,Cr these three channels and continuing to analyze separately,the other way round,there are some problems like the variation of parameters thresholds and the differences between the luminance and the chronance;(4)Discussing whether the watermark can resist both the once JPEG compression and twice JPEG compressions and the discussions about the tamper check and restoration of gray and color images are based on the twice JPEG compressions.It is found that the experiment results are foundamentally perfect and the facts that watermark can resist twice JPEG compressions expand its practicability.