Border-less clock free two-dimensional barcode and method for printing and reading the same
US6201901A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 1, 1998 |
| Grant date | Mar 13, 2001 |
| Priority date | — |
| Expiry date | Jun 1, 2018 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06K19/06037
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
Inventive two-dimensional barcodes, each having encoded digital information in a bitmap representing preferably randomized encoded data bits, are printed onto a printed medium. Preferably, error correction codes are added to the digital information to ensure that the decoding process accurately reproduce the digital information. In one embodiment, the bitmap may further include "anchor" bits in each corner, which are used as part of the skew estimation and deskewing processes during decoding. In a second embodiment, no "anchor" bits are required. The encoded digital information is mapped into the two-dimensional barcode in such a way as to minimize the errors caused by damage to particular rows and/or columns, for example, row damage caused by faxing the printed barcode. To extract the encoded digital information from the printed medium, the printed medium is scanned, then the bitmap is located within the printed medium. The skew of the bitmap, if any, is determined, and the bitmap is deskewed if necessary. The bitmap is then cropped, and the randomized digital information is read from the bitmap. The digital information is derandomized and any error correction codes are removed, i…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.