Method and system for frequency domain watermarking using a phase based filter signature
First Claim
1. A method for digitally watermarking digital image files, said method comprising:
- embedding a digital watermark into a digital image file; and
extracting the digital watermark from the digital image file,wherein said embedding comprises extracting magnitudes of Fourier frequencies from the digital image file, extracting phases of Fourier frequencies, encrypting a signature from the extracted phases, and reassembling the signature into the digital image file, andwherein said extracting comprises detecting the digital watermark to authenticate the digital image file.
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Abstract
The present invention is a digital watermarking technique Phasemark™ for image authentication. Using a signature extracted from the original image, the present invention hides an encoded version of the signature back into the original image, forming the watermarked image. The hiding is done in the frequency domain. Specifically, the present invention is a new transform domain digital watermarking technique that hides a signature obtained from the Fourier phases into the magnitude spectrum of the same host image. The detection process computes the discrete Fourier transform of the watermarked image, extracts and decodes the embedded signature, and then correlates it with calculated phase information. Correlation metrics determine the degree of authenticity of the image.
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Citations
11 Claims
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1. A method for digitally watermarking digital image files, said method comprising:
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embedding a digital watermark into a digital image file; and extracting the digital watermark from the digital image file, wherein said embedding comprises extracting magnitudes of Fourier frequencies from the digital image file, extracting phases of Fourier frequencies, encrypting a signature from the extracted phases, and reassembling the signature into the digital image file, and wherein said extracting comprises detecting the digital watermark to authenticate the digital image file. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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Specification