Method and apparatus for compensating for dirt or etched areas on a document platen
US5214470A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Apr 9, 1992 |
| Grant date | May 25, 1993 |
| Priority date | — |
| Expiry date | Apr 9, 2012 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N1/4097
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A method and apparatus are provided for detecting the presence of dirt or abrasions or etched areas on a document platen and for preventing these defects from being reproduced as unwanted spots on output copies. The platen is first scanned without a document placed thereon and an electronic image is generated and stored which contains information on the location of a dirt spot or inherent defects such as etched marks. Upon the initiation of a scanning mode with a document placed on the platen, the scanned electronic document image is subjected to a logical XOR process to correlate the previously stored spot location with the same location on the document image which is generated and stored. Once the spot location is determined, the spot is erased. A further logical step is used to determine whether the spot lies wholly or partially within any informational areas of the document image. To the extent there is such an overlap, the spot is restored to black in the overlapping areas.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.