Chroma noise reduction and transient improvement
US4935806A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Dec 30, 1988 |
| Grant date | Jun 19, 1990 |
| Priority date | — |
| Expiry date | Dec 30, 2008 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N9/646
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A digital chroma signal processor samples groups of three successive pixels and develops first and second difference signals therefrom. The first difference signals indicate changes in color and the second difference signal peaks those changes when combined with the original signal. A threshold detector determines when the changes are great enough to need peaking and operates a multiplexer that supplies a transient enhanced signal for a chroma signal above the threshold or a median signal for a chroma signal below the threshold. The median signal is developed for each sample group, along with minimum and maximum signals, by a criteria filter. A limiting coefficient adjusts the minimum and maximum signals to provide controlled amounts of overshoot and undershoot in the processed chroma signal.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.