Histogram-based intensity expansion
US6529211B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jun 22, 1999 |
| Grant date | Mar 4, 2003 |
| Priority date | — |
| Expiry date | Jun 22, 2019 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06T2207/10016
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A method and apparatus for selectively scaling portions of image data based on the intensity levels of historical image data. The selective scaling, or level expansion, provides improved images by increasing or decreasing the intensity of a portion of image pixels. Black level expansion reduces the intensity of dark pixels and is appropriate when a relatively large number of the image pixels have a high intensity level. White level expansion increases the intensity of bright pixels and is appropriate when a relatively large number of image pixels have a low intensity level. Level expansion is implemented by using histogram comparators 402 to compare the intensity of each pixel with a threshold, typically on a frame-by-frame basis. When an adequate number of pixels in each frame meet the threshold criteria, the level expansion is increased. Field accumulator 404 is used to determine whether and by how much the image data is scaled. Field accumulator 404 increments each time a frame meets the expansion criteria, as determined by the histogram comparators 402, and decrements each time a frame does not meet the expansion criteria. The value accumulated by the field accumulator 404 is u…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.