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Image watermarking in the fourier domain based on global features of concentric ring areas

: Funk, W.


Wong, W.P.; Delp, E.J. ; Society for Imaging Science and Technology -IS&T-; Society of Photo-Optical Instrumentation Engineers -SPIE-, Bellingham/Wash.:
Security and Watermarking of Multimedia Contents IV
Bellingham/Wash.: SPIE, 2002 (SPIE Proceedings Series 4675)
ISBN: 0-8194-4415-4
Conference on Security and Watermarking of Multimedia Contents <4, 2002, San Jose/Calif.>
Fraunhofer IGD ()
image watermarking; robust watermarking

This paper presents a blind decoding watermarking scheme that takes advantage of two basic properties of the Fourier transform: The image information is transformed into frequency bands centered around the origin of the coordinate system and the image information, the latter beeing independent from shifts in the original image. (i.e. pixel domain). These properties are exploited to embed a watermark that is inherently robust against translation an rotation in the pixel domain and shows considerable robustness against cropping and scaling as well. The amplitude part of the Fourier representation of the image is divided into rings, and each ring is subdivided into sections. A pair of sections is used to embed one bit of watermark information with the bit value being represented´by a predifined difference between the mean power values of the sections. The playload of the presented watermarking scheme strongly depends on the size of the image. Tests based on a leightweights implementation of the presented scheme were run with a watermark playload of 16 bits for an image of 512 by 512 pixels.