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Applied Optics

Applied Optics


  • Vol. 44, Iss. 15 — May. 20, 2005
  • pp: 3019–3023

Watermarks encrypted in a concealogram and deciphered by a modified joint-transform correlator

David Abookasis, Ofir Montal, Ohad Abramson, and Joseph Rosen  »View Author Affiliations

Applied Optics, Vol. 44, Issue 15, pp. 3019-3023 (2005)

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We describe an electro-optical method of deciphering a watermark from a recently invented encoded image termed a concealogram. The watermark is revealed as a result of spatial correlation between two concealograms, one containing the watermark and the other containing the deciphering key. The two are placed side by side on the input plane of a modified joint-transform correlator. When the input plane is illuminated by a plane wave, the watermark image is reconstructed on part of the correlator’s output plane. The key function deciphers the concealed watermark from the visible picture only when the two specific concealograms are matched. To illustrate the system’s performance, both simulation and experimental results are presented.

© 2005 Optical Society of America

OCIS Codes
(050.1950) Diffraction and gratings : Diffraction gratings
(070.2580) Fourier optics and signal processing : Paraxial wave optics
(070.4550) Fourier optics and signal processing : Correlators
(070.4560) Fourier optics and signal processing : Data processing by optical means
(090.1760) Holography : Computer holography
(100.2810) Image processing : Halftone image reproduction

Original Manuscript: February 27, 2004
Revised Manuscript: June 1, 2004
Manuscript Accepted: June 7, 2004
Published: May 20, 2005

David Abookasis, Ofir Montal, Ohad Abramson, and Joseph Rosen, "Watermarks encrypted in a concealogram and deciphered by a modified joint-transform correlator," Appl. Opt. 44, 3019-3023 (2005)

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