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Watermarks encrypted in a concealogram and deciphered by a modified joint-transform correlator.
David Abookasis1, Ofir Montal, Ohad Abramson
1Department of Electrical and Computer Engineering, Ben-Gurion University of the Negev, P.O. Box 653, Beer-Sheva 84105, Israel.
Applied Optics
|June 3, 2005
Summary
This study introduces an electro-optical technique to reveal hidden watermarks in novel encoded images called concealograms. Spatial correlation between a concealogram and its key reveals the watermark using a joint-transform correlator.
Area of Science:
- Optics and Photonics
- Image Processing
- Information Security
Background:
- Novel encoded images, termed concealograms, have been developed.
- Existing methods for watermark deciphering may lack efficiency or security.
- Optical correlation techniques offer potential for image deciphering.
Purpose of the Study:
- To present an electro-optical method for deciphering watermarks from concealograms.
- To demonstrate the use of spatial correlation for watermark retrieval.
- To validate the proposed method through simulation and experimentation.
Main Methods:
- Utilizing a modified joint-transform correlator (JTC).
- Performing spatial correlation between a concealogram and its deciphering key.
- Illuminating the input plane with a plane wave to reconstruct the watermark.
Main Results:
- Successful reconstruction of the watermark image on the correlator's output plane.
- Demonstration that the key correctly deciphers the concealed watermark only when matched with the specific concealogram.
- Validation of the method's performance via both simulation and experimental results.
Conclusions:
- The described electro-optical method effectively deciphers watermarks from concealograms.
- Joint-transform correlation provides a viable approach for secure image deciphering.
- The system's performance is confirmed through rigorous testing.