White reference data generating unit applied to shading correction system
US5317421A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jan 3, 1992 |
| Grant date | May 31, 1994 |
| Priority date | — |
| Expiry date | Jan 3, 2012 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N1/4076
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A white reference data generating unit which generates white reference data used in a shading correction process includes a line memory for storing white reference data, a determination circuit for determining whether or not the image data supplied from an image sensor is equal to or less than a predetermined threshold level, a updating circuit for updating the white reference data stored in the line memory to new white reference data calculated based on the white reference data stored in the line memory and input data while each line on a white reference plate is scanned, and a selector for supplying the image data, as the input data, to the updating circuit when the determination circuit determines that the image data is greater than the threshold level, and for supplying difference data, as the input data, to the updating circuit when the determination circuit determines that the image data is equal to or less than the threshold level, the difference data being obtained by subtracting a predetermined value from the white reference data stored in the line memory.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.