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Digital watermarking

  • US 5,915,027 A
  • Filed: 11/05/1996
  • Issued: 06/22/1999
  • Est. Priority Date: 11/05/1996
  • Status: Expired due to Term
First Claim
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1. A method for inserting a watermark signal into data to be watermarked comprising the steps of:

  • dividing data to be watermarked into a plurality of subregions;

    computing frequency coefficients of the data to be watermarked in each subregion;

    spread spectrum modulating a watermark signal to be inserted by mapping the watermark signal into a PN (pseudo-random noise) sequence;

    spectral shaping the PN sequence as a function of the average power in each frequency coefficient of the data; and

    inserting each spectral shaped PN sequence into predetermined coefficients in the data in each subregion.

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