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Rotation, scale, and translation resilient public watermarking for images using a log-polar fourier transform

  • US 6,282,300 B1
  • Filed: 01/21/2000
  • Issued: 08/28/2001
  • Est. Priority Date: 01/21/2000
  • Status: Expired due to Term
First Claim
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1. A method for inserting a watermark signal in digital image data to obtain a watermarked image, the method comprising the steps of:

  • computing a log-polar Fourier transform of the image data to obtain a log-polar Fourier spectrum;

    projecting the log-polar Fourier spectrum down to a lower dimensional space to obtain an extracted signal;

    modifying the extracted signal such that it is similar to a target watermark;

    performing a one-to-many mapping of the modified signal back to log-polar Fourier transform space to obtain a set of watermarked coefficients; and

    performing an inverse log-polar Fourier transform on the set of watermarked coefficients to obtain a watermarked image.

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