Image reader and image reading method
US6839153B1 · kind B1 · utility
Assignee
Inventor
Key dates
| Filing date | Mar 8, 2000 |
| Grant date | Jan 4, 2005 |
| Priority date | — |
| Expiry date | Mar 8, 2020 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N1/4097
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
Even if there may exist a difference in reading density between reading positions, there will be provided an image reader capable of accurately detecting and removing streaks-shaped noise caused by the adhesion of dust particles to the reading unit. A CCD reads an original at each reading position, and image data A and B in each reading position are obtained from an output delay circuit and a shading correction circuit. A streak detection circuit judges a difference A−B between each image data through the use of a threshold corrected on the basis of an average density difference between each image data A and B, and outputs black streak detection data in accordance with the judgment result. A streak removal circuit always outputs the image data A, but if black streak detection data is outputted, image data B corrected on the basis of the average density difference is outputted in place of the image data A.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.