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Method and image forming apparatus, and printing system for recording invisible information recording

  • US 20020027674A1
  • Filed: 08/31/2001
  • Published: 03/07/2002
  • Est. Priority Date: 09/01/2000
  • Status: Active Grant
First Claim
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1. An invisible information recording method comprising:

  • recording a digital image on a blank on a sheet of paper; and

    recording information in the form of pixels so sized as to be invisible to a naked eye and at a print density invisible to the naked eye.

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