Image analysis – Applications
Reexamination Certificate
2000-03-07
2004-03-02
Boudreau, Leo (Department: 2621)
Image analysis
Applications
C382S250000
Reexamination Certificate
active
06700991
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a digital watermark; more specifically, the invention relates to a method of providing hidden digital watermarks in images.
2. Description of Related Art
Due to the rapid and extensive growth of electronic publishing industry, issues regarding protection of copyright have become increasingly important, in a large part because digital data in media form is easily copied and manipulated. One potential solution for claiming the ownership of a digital image is to use electronic stamps or so-called watermarks, which are embedded into the images, wherein the watermarks containing the copyright information should be added to the original digital image data without being perceptually visible to the viewers.
In order to achieve the above objects, conventional technologies provide an image authentication technique by embedding digital watermarks into original images. Details regarding technologies of this sort, which are still being developed, are disclosed in “Electronic marking and identification techniques to discourage document copying” by J. T. Brassil, S. Low, N. F. Maxemchuk, and L. O'Gorman, pp. 1495-1504, IEEE J. Select. Areas Commum., vol. 13, October 1995; there different encoding methods are mentioned in the document to conceal digital markings in a document. Furthermore, related publications including “Applying signatures on digital images” by I. Pitas and T. H. Kaskalis, pp. 460-463, in Proc. IEEE Nonlinear Signal and Image Processing, June 1995; “Spatial method for copyright labeling of digital images” by O. Bruyndonckx, J. J. Quisquater, and B. Macq, pp. 456-459, in Proc. IEEE Nonlinear Signal and Image Processing, June 1995; “Image authentication for a slippery new age” by S. Walton, pp. 18-26, Dr. Dobb's Journal, April 1995; and “Techniques for data hiding” by W. Bender, D. Gruhl, and N. Morimoto, p. 40, Proc. SPIE, vol. 2420, February 1995 are conventional technologies to provide digital watermarks in spatial domain.
However, while technologies for concealing added information in digital data are readily available, it is difficult to make sure that the digital watermarks survive common digital image processing operations such as image compression (as in JPEG format), change of geometry (for example, image cropping, ornamental change, etc.), D/A-A/D converting (for example, scanning on a printout), noise interference, and so forth, with the biggest challenge of all being maintaining the watermark on a reduced image after a lossy data compression that eliminates secondary information. A technology for providing digital watermarks in a frequency domain, which superimposes a copyright code and its random sequence of locations for embedding on the image based on a JPEG model, is also readily available, as disclosed in “Toward robust and hidden image copyright labeling” by E. Koch and J. Zhao, pp. 452-455, in Proc. IEEE Nonlinear Signal and Image Processing, June 1995, “Secure spread spectrum watermarking for multimedia” by I. J. Cox, J. Kilian, T. Leighton, and T. Shammoon, in Tech. Rep. 95-10, NEC Res. Inst., Princeton, N.J., 1995, and “Transparent robust image watermarking” by M. D. Swanson, B. Zhu, and A. H. Tewfik, pp. 211-214, in Proc. ICIP '96, etc.
However, the above-mentioned conventional technologies do not take into consideration the embedding of the digital watermarks with visible recognizable patterns such as signatures in the forms of Chinese characters and personal seals.
SUMMARY OF THE INVENTION
In order to improve on the aforementioned technical shortcomings and inadequacies, the present invention is related to a method of providing hidden digital watermarks in images, comprising: providing an original image and a watermark image; applying pseudo-random permutations to the watermark image for generating a dispersed watermark image; applying block-based permutations to the original image and the dispersed watermark image in order to form a plurality of original image blocks with each of the watermark blocks dispersed over the corresponding image block only; applying FDCT (Forward Discrete Cosine Transform) on each of the original image blocks independently so that each of the original image blocks is transformed into a DCT coefficient block that corresponds to different frequency ranges; embedding said watermark image blocks into said DCT coefficient blocks, which are the original image blocks of specified frequency range, in order to form a plurality of combined DCT coefficient blocks; applying IDCT (Inverse Discrete Cosine Transform) to the combined DCT coefficient blocks to form an embedded watermark image.
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Bender et al., “Techniques for data hiding”, Massachusetts Institute of Technology, Media Library, pp. 1-23, 1996.
Brassil et al., “Electronic Marking and Identification Techniques to Discourage Document Copying”, IEEE Journal on Selected Areas in Communications, vol. 13, pp. 1495-1504, Oct. 1995.
Bruyndonckx et al., “Spatial Method for Copyright Labeling of Digital Images”, pp. 456-459.
Cox et al., “Secure Spread Spectrum Watermarking for Multimedia”, pp. 1-33, NEC Research Institute.
Koch et al., “Towards Robust and Hidden Image Copyright Labeling”, pp. 452-455, Fraunhofer Institute of Computer Graphics.
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Hsu Chiou-Ting
Wu Ja-Ling
Akhavannik Hussein
Boudreau Leo
Cyberlink Corporation
Fish & Richardson P.C.
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