Method and system for frequency domain watermarking using a phase based filter signature
First Claim
1. A method for digitally watermarking digital image files comprising:
- embedding a digital watermark into a digital image file;
extracting said digital watermark from a digital image file;
detecting said digital watermark to authenticate said 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
15 Claims
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1. A method for digitally watermarking digital image files comprising:
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embedding a digital watermark into a digital image file;
extracting said digital watermark from a digital image file;
detecting said digital watermark to authenticate said digital image file.
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2. A method for digitally watermarking digital image files comprising:
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embedding a digital watermark into a digital image file;
the step of embedding comprising;
extracting magnitudes of Fourier frequencies in said digital image file;
extracting phases of Fourier frequencies in said digital image file;
encrypting a signature from the phases of said digital image file;
reassembly of said signature into said digital image file;
extracting said digital watermark from a digital image file;
the step of extracting comprising;
detecting said digital watermark to authenticate said digital image file. - View Dependent Claims (3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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Specification