METHOD OF IMAGING A CODING PATTERN WITH DATA ELEMENTS ENCODING BY MULTI-PULSE POSITION MODULATION

• US 20090078767A1
• Filed: 07/24/2008
• Published: 03/26/2009
• Est. Priority Date: 09/21/2007
• Status: Active Grant

• Current Assignee: Silverbrook Research Pty Limited
• Original Assignee: Silverbrook Research Pty Limited
• Inventors: Lapstun, Paul
• Granted Patent: US 8,070,071 B2
• Time in Patent Office: Days
• US Class Current: 235/454
• CPC Class Codes: G06F 3/1206 resulting in increased flexibility in input data format or job format or job type
• CPC Class Codes: G06F 3/1265 Printing by reference, e.g. retrieving document/image data for a job from a source mentioned in the job
• CPC Class Codes: G06F 3/1284 Local printer device
• CPC Class Codes: G06K 19/06037 multi-dimensional coding

Abstract

A method of imaging a coding pattern disposed on a surface of a substrate. The method comprises the steps of: (a) capturing an image of a portion of the coding pattern; and (b) low-pass filtering said captured image so as to obscure data elements and preserve target elements. The coding pattern comprises and target elements and data elements, which encode data values by multi-pulse position modulation.

Claims

1. A method of imaging a coding pattern disposed on a surface of a substrate, said method comprising the steps of:

(a) capturing an image of a portion of said coding pattern, said coding pattern comprising;

a plurality of target elements defining a target grid, said target grid comprising a plurality of cells, wherein neighboring cells share target elements;

a plurality of data elements contained in each cell; and

a plurality of tags, each tag being defined by a plurality of contiguous cells, each tag comprising respective local tag data encoded by a respective set of said data elements, wherein said data elements encode data values by multi-pulse position modulation; and

(b) low-pass filtering said captured image so as to obscure said data elements and preserve said target elements.

2. The method of claim 1, wherein said data elements are macrodots.

3. The method of claim 2, wherein a portion of data is represented by m macrodots, each of said macrodots occupying a respective position from a plurality of predetermined possible positions p within said cell, the respective positions of said macrodots representing one of a plurality of possible data values.

4. The method of claim 3, wherein m is an integer of 2 or more, and p>

m.

5. The method of claim 3, wherein p is 6 and m is 2 or 3.

6. The method of claim 3, wherein said portion of data is a Reed-Solomon symbol.

7. The method of claim 6, wherein each cell defines a symbol group, each symbol group comprising a plurality of Reed-Solomon symbols encoded by a plurality of said data elements.

8. The method of claim 7, wherein said tag data is encoded as a local codeword comprised of a set of said Reed-Solomon symbols.

9. The method of claim 8, wherein each local codeword identifies a location of a respective tag.

10. The method of claim 1 comprising the further steps of:

observing a perspective distortion of said preserved target elements due to a 3D orientation of a reader relative to said surface; and

calculating a 2D perspective transform using said target elements.

11. A system for imaging a coding pattern disposed on a surface of a substrate, said system comprising:

(A) said substrate, wherein said coding pattern comprises;

a plurality of target elements defining a target grid, said target grid comprising a plurality of cells, wherein neighboring cells share target elements;

a plurality of data elements contained in each cell; and

a plurality of tags, each tag being defined by a plurality of contiguous cells, each tag comprising respective local tag data encoded by a respective set of said data elements, wherein said data elements encode data values by multi-pulse position modulation; and

(B) an optical reader comprising;

an image sensor for capturing an image of a portion of said coding pattern; and

a processor configured for low-pass filtering said captured image so as to obscure said data elements and preserve said target elements.

12. The system of claim 11, wherein said data elements are macrodots.

13. The system of claim 12, wherein a portion of data is represented by m macrodots, each of said macrodots occupying a respective position from a plurality of predetermined possible positions p within said cell, the respective positions of said macrodots representing one of a plurality of possible data values.

14. The system of claim 13, wherein m is an integer of 2 or more, and p>

m.

15. The system of claim 13, wherein p is 6 and m is 2 or 3.

16. The system of claim 13, wherein said portion of data is a Reed-Solomon symbol.

17. The system of claim 16, wherein each cell defines a symbol group, each symbol group comprising a plurality of Reed-Solomon symbols encoded by a plurality of said data elements.

18. The system of claim 17, wherein said tag data is encoded as a local codeword comprised of a set of said Reed-Solomon symbols.

19. The system of claim 11, wherein said reader is an optically imaging pen having a nib.

20. The system of claim 11, wherein said processor is further configured for:

observing a perspective distortion of said preserved target elements due to a 3D orientation of said reader relative to said surface; and

calculating a 2D perspective transform using said target elements.