Protection against various attacks by using semi fragile technique

摘要

A unique semi-fragile watermarking scheme for verification and tamper detection of digital images is proposed in this paper. A watermarking field is necessary while protecting or to resolving the copyright integrity of audio, video and multimedia data files. The need for secure information over network is of high security when the information is shared over network or retrieved from network. There are many promising modifications, such as cropping an image, lossy compression of the information or adding noises and the protections against such attacks are required. In this paper, a semi fragile watermarking approach is proposed. The approach aims to provide a high robustness and imperceptibility with perfectly image recovery zone. These watermarking scheme internments the information content of the image in few coefficients related to other transforms. The originality of the approach is that input image is segmented into 64 images which is then watermarked and embedded into the pseudo randomly determined coefficients. At the receiver side, the extracted and generated watermarked image is combined into blocks of constant size. This scheme exhibits higher Peak signal to noise ratio (PSNR) i.e. 60.2204. Moreover, the proposed technique is robust against some usually used image processing processes [1] such as additive noise with PSNR of 49.06315, contrast adjustment with 47.0969 value of PSNR, compression with PSNR of 55.6190. This technique provides good results against cropping and tampering attacks along with PSNR of 41.6339 and 39.0486 respectively with least computational cost.