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Apparatus and method for watermark data insertion and apparatus and method for watermark data detection

  • US 6,240,121 B1
  • Filed: 07/09/1998
  • Issued: 05/29/2001
  • Est. Priority Date: 07/09/1997
  • Status: Expired due to Fees
First Claim
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1. A watermark data insertion method for inserting watermark data into an input original signal, comprising:

  • a frequency transform step of applying a frequency transform to the original signal to form an intermediate signal;

    a watermark data insertion step of inserting the watermark data into a first set of frequency components of the intermediate signal; and

    a frequency inverse transform step of applying an inverse frequency transform to the intermediate signal, the watermark data having been inserted into the intermediate signal, thereby obtaining a signal containing the watermark data embedded therein, wherein the watermark data insertion step comprises;

    determining, based on pseudo random numbers, the first set of frequency components of the intermediate signal into which the watermark data is inserted; and

    using a second set of frequency components of the intermediate signal as a reference signal, the watermark data not being inserted into the second set of frequency components.

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