Image analysis – Applications
Reexamination Certificate
2000-02-04
2003-10-14
Chang, Jon (Department: 2623)
Image analysis
Applications
C382S250000
Reexamination Certificate
active
06633653
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to watermarked digital images. In particular, it relates to methods for improving confidence in and for authentication of watermarked digital images.
In order to increase confidence of use of digital images as evidence, possibly in a court of law, there is a significant need to demonstrate that an image has not been tampered with.
BACKGROUND OF THE INVENTION
It is known to use audit trails, in which information about when an image was processed is appended to the image, but these methods are only applicable once an image has been registered onto a system. Such audit trails therefore cannot detect any unauthorized operations prior to registration on a computer, and may not be able to report on the type of processing done at any one time. Audit trails can also be avoided or corrupted, whether deliberately or accidentally.
Image watermarking is a known technique. In this technique, a known binary pattern or signature is embedded into an image at the moment of image acquisition. Such watermarks are called “robust” because they are designed to remain intact regardless of any post-processing of the image such as filtering, cropping etc. While such watermarks do provide a useful degree of protection, they can at present not be wholly relied on and they cannot always possess the required degree of surety that an image has not been tampered with in order for the image to be used as evidence under the strict rules of courts of law, etc.
Ruanaidh, Dowling and Boland “Phase Watermarking of Digital Images”, IEEE INTCONF Image Processing, Vol. 3, Lausanne, Switzerland, September 1996, pp 239 to 241, describes a technique for watermarking digital images in which an image is divided into blocks of a selected size (e.g. 16×16 pixels). A discrete Fourier transform (DFT) is applied to the luminance component of the image on a block by block basis. The DFT is a complex value and thereby generates a modulus and a phase. The resulting watermark comprises a binary string of 1's and 0's which may represent, for example, a company logo, a user authentication code, date/time/location information and so on. The watermark is embedded in the image by altering the phase of selected DFT coefficients.
The present invention arose in an attempt to provide an improved method of authenticating, and thereby improve confidence in, a watermarked image.
REFERENCES:
patent: 5930369 (1999-07-01), Cox et al.
patent: 6285775 (2001-09-01), Wu et al.
patent: 0 828 372 (1998-03-01), None
“Secure Spread Spectrum Watermarking for Multimedia” by Ingemar Cox et al. NEC Research Institute Technical Report 95-10 1995.*
“DCT-based Watermark Recovering without Resorting to the Uncorrupted Original Image” by A. Piva et al. IEEE Signal Processing Society 1997 International Conference on Image Processing.*
“Improved robust watermarking through attack characterization” by Deepa Kundur et al. Optics Express 485 1998.*
“Copyright protection of digital images by embedded unperceivable marks” by Mauro Barni et al. 1998.*
Fridrich J: “Robust Bit Extraction from Images”; Proceedings of the International Conference on Multimedia Computing and Systems, Jun. 1999, XP000939253, p. 536, right-hand column, line 35—p. 537, right-hand column, line 42.
Kundur D. et al.: “Attach Characterization for Effective Watermarking”; Kobe, Japan, Oct. 24-28, 1999, Los Alamitos, Ca: IEEE, US, Oct. 1999, pp. 240-244, XP000939230, ISBN: 0-7803-5468-0, p. 242, left-hand column, line 9-line 22.
Ruanaidh JJKO et al.: “Phase Watermarking of Digital Images” Proceedings of the International Conference on Image Processing (ICIP), US, New York, IEEE, Sep. 16, 1996, pp. 239-242, XP000199952, ISBN: 0-7803-3259-8 the whole document.
Hobson Paola Marcella
Tay Lai Hock
Chang Jon
Davis Valerie M.
Kim Charles
Motorola Inc.
Santema Steven R.
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