Improved Digital Watermark Robustness against Translation and/or Cropping of an Image Area

Takao NAKAMURA  Hiroshi OGAWA  Atsuki TOMIOKA  Youichi TAKASHIMA  

IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E83-A   No.1   pp.68-76
Publication Date: 2000/01/25
Online ISSN: 
Print ISSN: 0916-8508
Type of Manuscript: Special Section PAPER (Special Section on Cryptography and Information Security)
digital watermark,  image processing,  orthogonal transform,  spread spectrum,  copyright protection,  

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Watermarking methods that employ orthogonal transformations are very robust against non-geometrical modifications such as lossy compression, but attaining robustness against image translation or cropping is difficult. This report describes a watermarking method that increases robustness against geometrical modifications such as image translation and cropping by embedding watermark data in the frequency component of an image and detecting that data by considering the phase difference of the coefficients that results from translation of the image. Experimental results demonstrate the robustness of this method against both non-geometrical image changes and image translation and cropping.