Weighted-pixel characteristic sensing system
US4748679A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 25, 1986 |
| Grant date | May 31, 1988 |
| Priority date | — |
| Expiry date | Jul 25, 2006 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N1/029
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A system for sensing a characteristic of a document, e.g. translucency, by using radiation from the document at a specific window area. The identified window area is illuminated to provide radiation from the area which is sensed by pixel dissection so that pixels of central location in the window area are weighted for greater significance. The pixel weighting attributes greater significance to the central portion of the defined area thereby increasing the tolerance of the system to misalignment of the window area. The observed characteristic is reduced to signal representations which are compared with registered values as to authenticate the document. Pixel-weighting techniques include overlapped pixels, filtered pixels and algebraically weighted pixels.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.