Robust Reversible Watermarking For Geometric Attack by Proposed Pixel Replacement Method

Volume 2, Issue 1 January February 2013 Page 186 Abstract: Reversible watermarking is broadly used in military and medical applications. In this paper we are presenting a novel pixel replacement method, whose watermark is robust to geometric attack as well as it has maximum embedding capacity than all histogram shifting methods. This idea is generated from histogram shifting method, a well known method for reversible watermarking. Our method also maintains comparable quality of watermarked images. Other techniques affected with geometric attacks such as rotation, scaling and translation are not robust watermarking techniques. They do not recover 100% similar watermark and image with original. Our few modifications proved that our method is robust watermarking method with 100% similarity between original and recovered watermark. In our method, PSNR is slightly reduced than histogram shifting method, (minimum 48 dB) but still it is higher than Dinu Coltuc’s RCM method and Tian’s Difference expansion method. The embedding capacity of our method is more than histogram shifting method but it is lesser than RCM and difference expansion method. By compromising quality of watermarked image, embedding capacity can be improved more than difference expansion, RCM and histogram shifting method. Our proposed replacement method is less complex than difference expansion and RCM method. So optimizing quality and embedding capacity, this method can be made superior. This method gets a crown in her head, as we have made it robust watermarking for geometric attack by combining with existing Geometric Transformation Correction method. KeywordsReversible Watermarking, histogram shifting, embedding capacity, processing time, PSNR, robust and geometric attack.