Video contrast enhancer
US5808697A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 14, 1996 |
| Grant date | Sep 15, 1998 |
| Priority date | — |
| Expiry date | Jun 14, 2016 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG09G2360/16
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A video contrast enhancer enhances luminance contrast by dividing each video frame or field into blocks, calculating a mean luminance level for each block, selecting mapping functions on the basis of these mean luminance levels over a series of frames or fields, and mapping the video luminance levels according to the selected mapping functions. Color-saturation contrast is enhanced by modifying the amplitude of the modulated chrominance signal by the histogram equalization method, preferably by making a single linear modification in each period of the chrominance signal, so that color phase is not affected. For video signals with non-picture bands, these enhancements are preferably restricted to the picture area. If a black offset is present, it is preferably removed.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.