Automatic brightness compensation for fluorography systems
US5012504A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 26, 1989 |
| Grant date | Apr 30, 1991 |
| Priority date | — |
| Expiry date | Dec 26, 2009 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH05G1/60
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
The brightness of an X-ray video image during fluorography is maintained at a substantially constant level by a control circuit which varies the X-ray dose in relation to changes in the average brightness of the X-ray image. Selected picture elements of the image which lie within a defined region in the image and which have a brightness above a given level are used to derive the average X-ray image brightness. The brightness of the selected picture elements are summed and the number of such picture elements counted. The summation of the brightness and the picture element count are both scaled by a factor of 2.sup.n to reduce the size of the numbers of the complexity of the averaging circuitry. The scaled brightness summation is divided by the scaled picture element count and the result is stored as the average X-ray image brightness.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.