Processing methods using adaptive threshold for removal of chroma/luminance cross-talk in quadrature-modulated subcarrier color television systems
US4731660A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 20, 1987 |
| Grant date | Mar 15, 1988 |
| Priority date | — |
| Expiry date | Feb 20, 2007 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N9/646
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A comb filter for improved cross-color reduction with improved visible diagonal resolution is provided for processing a luminance component of a quadrature modulated color subcarrier television signal in the vicinity of the color subcarrier pass band. The comb filter comprises an input and an output, and has a first path including a delay circuit for delaying the luminance component and a subtraction circuit connected between the input and the output, and has a second path including a chrominance type comb filter, a band pass filter for passing a spectrum in the vicinity of the color subcarrier pass band both being followed by a variable threshold circuit connected to the subtraction circuit. The variable threshold circuit is for inhibiting the signal in the second path below a variable threshold. The variable threshold is derived as a function of at least one of luminance diagonal transition level, chroma level and averaged luminance activity in the spectrum in the vicinity of the color subcarrier.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.