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Gaurav Sharma
ECE Department
University of Rochester
Friday, Oct. 1, 11:00am
LC 102, Brooklyn Campus, Polytechnic University
Digital representation and communication make information dissemination easy in today's networked world. The ease of manipulation of the digital data, however, also emphasizes the need for integrity verification. For multi-media signals, authentication watermarks offer not only the capability for secure integrity verification but also the ability to localize tampered signal regions. In this talk, we present our recent work in this area incorporating three main ideas: a hierarchical image authentication watermark, a loss-less data embedding technique, and a new framework for lossless authentication. The hierarchical watermark allows authentication of integrity over a pyramidal hierarchy, thus offering a trade-off between security and localization under collage (vector quantization) attacks. The lossless data embedding method provides a high-capacity low-distortion method for watermark insertion that is reversible and allows recovery of original image data --- a crucial requirement in some medical, legal and military applications where integrity verification is important but common watermarking distortion is unacceptable. The new lossless authentication framework improves on existing lossless authentication watermarks by allowing authentication of the image prior to recovery. This in turn enables tamper localization which is often not realized in existing methods. Finally, we present a lossless authentication watermark (LAW) that implements the new framework by combining the hierarchical authentication and the lossless embedding methods.
Gaurav Sharma
received the PhD degree in electrical engineering and an MS in Applied
Mathematics from North Carolina State University, Raleigh in 1996 and 1995,
respectively. From Aug. 1996 to Aug. 2003 he was employed as a member of the
research and staff at Xerox Corporation's Research and Technology Division in
Webster, NY. Prior to his resignation, he held the position of Principal
Scientist and led a research project on color imaging. Since Aug. 2003 he is an
Associate Professor in the Electrical and Computer Engineering Dept at the
University of Rochester. His research interests include multimedia/print
security, color science and imaging, image halftoning, and signal restoration.
For further information or to arrange a meeting with the speaker please contact Nasir Memon