Method for improving contrast in picture sequences
US6148103A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jan 28, 1998 |
| Grant date | Nov 14, 2000 |
| Priority date | — |
| Expiry date | Jan 28, 2018 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06T2207/10016
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
The invention relates to adjusting contrast in television pictures and other natural picture sequences. In the method according to the invention, the pictures of the picture sequence are gathered into histograms which are processed in certain fashion in order to improve contrast in the pictures, whereafter there are formed mapping functions on the basis of the processed histograms, and the pixel values of the pictures in the picture sequence are then altered on the basis of said mapping functions. The histograms are processed so that from each class where the magnitude of values surpasses a given, predetermined limit, there are cut off all values surpassing said limit, which are then redistributed in the histogram, to classes nearest to the class under observation. The weighting of the distribution controlling the redistribution of the cut-off values advantageously varies according to the class under observation, so that near the low-value end of the histogram, the values are redistributed mainly to classes with higher values than in the class under observation, and near the high-value end of the histogram, the cut-off values are redistributed mainly to classes with lower values th…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.