Research On Technology Of DWT Semi-fragile Watermarking For Content Authentication

With the wide spread of image processing software, people can easy replicate and modifydigital image. Therefore, digital image copyright protection and content authentication becamethe major issues to be solved .Semi-fragile watermarking technology is a measure to solve theabove problems effectively. A novel semi-fragile watermarking scheme for image authenticationand tamper localization is proposed based on wavelet transformation. In this algorithm, thewatermark is generated by extracting image feature from the approximation subband in thewavelet domain. The linear congruential pseudo random number generator is used to control thewatermark embedding location. The scheme can resist the mild modification of digital image andable to detect the malicious modifications precisely.A new watermarking algorithm in DWT domain to resist JPEG compression is presentedbased on human visual system (HVS). In this algorithm, the watermark used for contentauthentication is generated by extracting image feature. The watermark is embedded by adjustingDWT coefficients in detail subband of block image. Use just noticeable difference (JND) ofblock image to adaptive control of wavelet coefficient modifier, thus enhanced the watermarktransparency and the watermark anti-JPEG performance. The experimental result indicated thatthis algorithm has the very good anti-JPEG compression performance and the image distortionlocalization function.