Digital Watermarking is the art and science of embedding information in existing digital content for Digital Rights Management (DRM) and authentication. Reversible watermarking is a class of (fragile) digital watermarking that not only authenticates multimedia data content, but also helps to maintain perfect integrity of the original multimedia "cover data." In non-reversible watermarking schemes, after embedding and extraction of the watermark, the cover data undergoes some distortions, although perceptually negligible in most cases. In contrast, in reversible watermarking, zero-distortion of the cover data is achieved, that is the cover data is guaranteed to be restored bit-by-bit. Such a feature is desirable when highly sensitive data is watermarked, e.g., in military, medical, and legal imaging applications. This work deals with development, analysis, and evaluation of state-of-the-art reversible watermarking techniques for digital images. In this work we establish the motivation for research on reversible watermarking using a couple of case studies with medical and military images. We present a detailed review of the state-of-the-art research in this field. We investigate the various subclasses of reversible watermarking algorithms, their operating principles, and computational complexities. Along with this, to give the readers an idea about the detailed working of a reversible watermarking scheme, we present a prediction-based reversible watermarking technique, recently published by us. We discuss the major issues and challenges behind implementation of reversible watermarking techniques, and recently proposed solutions for them. Finally, we provide an overview of some open problems and scope of work for future researchers in this area.
About the Author: Ruchira Naskar received a B.Tech degree in Information Technology from West Bengal University of Technology in 2008, and an M.Tech degree in Information Technology from Indian Institute of Technology, Kharagpur in 2010. Since July 2010, she has been a research scholar in the Department of Computer Science and Engineering at Indian Institute of Technology, Kharagpur. Her research interest is in the areas of digital watermarking, multimedia content protection and cryptography. Currently she is working as an Assistant Professor at the National Institute of Technology Rourkela, India.Rajat Subhra Chakraborty has been an Assistant Professor in the Computer Science and Engineering Department of IIT Kharagpur since 2010. He received a Ph.D. in Computer Engineering from Case Western Reserve University (USA) and a B.E. (Hons.) in Electronics and Telecommunication Engineering from Jadavpur University (India) in 2005. His professional experience includes a stint as CAD Software Engineer at National Semiconductor, and a graduate internship at AMD Headquarters at Santa Clara (California). His research interests include Hardware Security including: design methodology for hardware IP/IC protection; Hardware Trojan detection and prevention through design and testing, attacks on hardware implementation of cryptographic algorithms; and reversible watermarking for digital content protection. Dr. Chakraborty has published over 45 articles in internationaljournalsandconferences. He has delivered keynote talks and tutorials at several international conferences and workshops, and has rendered his service as a reviewer and program committee member for multiple international conferences and journals. He is the co-author of three book chapters and two forthcoming books and was one of the recipients of the IBM Faculty Award for 2012. He holds one US patent, and two more international patents and one Indian patent have been filed based on his research work. Dr. Chakraborty is a member of IEEE and ACM.