Method and apparatus for encoding paper with information

• US 6,608,919 B1
• Filed: 02/29/2000
• Issued: 08/19/2003
• Est. Priority Date: 11/10/1999
• Status: Expired due to Term

• Current Assignee: Digimarc Corporation
• Original Assignee: Digimarc Corporation
• Inventors: Alattar, Adnan M.
• Primary Examiner(s): Patel, Jayanti K.
• Application Number:
  US09/515,545
• Time in Patent Office: 1,267 Days
• Field of Search: 382/100, 382/112, 382/135, 382/137, 382/138, 382/181, 382/191, 382/108, 382/219, 382/232, 382/280, 382/278, 382/276, 382/312, 356/456, 358/16, 358/456, 380/54, 380/23, 713/150, 162/123, 162/125, 162/130-140, 101/321, 101/3.1, 283/67, 283/72
• US Class Current: 382/135
• CPC Class Codes: D21F 11/00 Processes for making continuous lengths of paper, or of cardboard, or of wet web for fibre board production, on paper-making machines
• CPC Class Codes: D21F 9/00 Complete machines for making continuous webs of paper
• CPC Class Codes: G03G 21/046 by discriminating a special original, e.g. a bank note
• CPC Class Codes: G06T 1/0021 Image watermarking
• CPC Class Codes: G06T 2201/0052 Embedding of the watermark in the frequency domain

Abstract

Paper is textured with a pattern that yields a known signature signal when transformed to the frequency domain. This signature can be used for various purposes, including determining the angular orientation of the paper when scanned, conveying a plural-bit digital watermark, and for simple document recognition purposes (e.g., photocopiers that refuse to reproduce banknotes). The texturing can be effected during the paper-making process, e.g., by shaping the surface of a de-watering element accordingly.

Claims

1. A method of determining a transformation of a paper document including:

optically scanning the paper document to generate scan data;

transforming the scan data to a frequency domain;

identifying frequency components in the transformed scan data corresponding to texture resulting from the paper'"'"'s manufacture; and

determining from said frequency components one or more possible transformations of the scanned documents from a reference state.

2. The method of claim 1 that includes determining from said frequency components a rotation of the scanned document from a reference orientation.

3. The method of claim 1 that includes determining from said frequency components a scale of the scanned document from a reference scale.

4. The method of claim 1 that includes determining from said frequency components a translation of the scanned document from a reference translation.

5. The method of claim 1 wherein the texture results from a de-watering element used in the paper'"'"'s manufacture.

6. A method including:

optically scanning a paper document to generate scan data;

transforming the scan data to a frequency domain;

identifying frequency components in the transformed scan data corresponding to texture resulting from the paper'"'"'s manufacture; and

interpreting said identified frequency components to yield payload data including at least a registration indicator.

7. The method of claim 6 that includes determining from the registration indicator a rotation of the scanned document from a reference orientation.

8. The method of claim 6 that includes determining from the registration indicator a scale of the scanned document from a reference scale.

9. The method of claim 6 that includes determining from the registration indicator a translation of the scanned document from a reference translation.

10. The method of claim 6 wherein the texture results from a de-watering element used in the paper'"'"'s manufacture.

11. A paper-making process including:

defining a frequency-domain signal, wherein the frequency-domain signal comprises an orientation component;

inverse transforming the frequency-domain signal to yield a two-dimensional pattern in the spatial domain;

shaping an element of the paper-making apparatus in accordance with said spatial domain pattern; and

imparting said pattern to a paper surface, wherein the orientation component provides an orientation reference for paper made according to said paper-making process.

12. A printing process using paper made according to the method of claim 11, the printing process comprising:

aligning printing on the paper so as to be oriented in a predetermined manner with respect to the pattern on the paper surface, wherein transforming optical scan data corresponding to said pattern into a frequency domain reveals an orientation of the paper.