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Multiple transform utilization and applications for secure digital watermarking

  • US 6,205,249 B1
  • Filed: 04/02/1998
  • Issued: 03/20/2001
  • Est. Priority Date: 04/02/1998
  • Status: Expired due to Term
First Claim
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1. A method for encoding a message into digital information, the digital information including a plurality of digital blocks, comprising the steps of:

  • transforming each of the digital blocks into the frequency domain using a fast Fourier transform;

    identifying a plurality of frequencies and associated amplitudes for each of the transformed digital blocks;

    selecting a subset of the identified amplitudes for each of the digital blocks using a primary mask from a key;

    choosing message information from the message using a transformation table generated with a convolution mask; and

    encoding the chosen message information into each of said transformed digital blocks by altering the selected amplitudes based on the chosen message information.

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