Fiducial mark patterns for graphical bar codes
US6742708B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jun 7, 2001 |
| Grant date | Jun 1, 2004 |
| Priority date | — |
| Expiry date | Jun 10, 2021 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06K19/06037
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
Fiducial mark patterns for graphical bar codes (i.e., images that contain inconspicuous graphical modulations that encode embedded information) that are characterized by high detection robustness and good local deformation tracking are described. In one bar coding method, a base image is modulated with a graphical encoding of a message to produce a graphical bar code, and a fiducial mark pattern comprising a plurality of dots arranged to track one or more reference locations and local deformation across the graphical bar code is generated. In another bar coding method, fiducial mark candidates are identified in a fiducial mark pattern, a fiducial mark path is computed based upon one or more of the identified fiducial mark candidates, and one or more reference locations are identified based upon the computed fiducial mark path.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.