Chroma key switching signal generator
US4386363A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Apr 10, 1981 |
| Grant date | May 31, 1983 |
| Priority date | — |
| Expiry date | Apr 10, 2001 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N9/75
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A wideband chroma key switching signal is generated from lower bandwidth chrominance signals in a video signal by first conventionally generating a chroma key switching signal from these chrominance signals, and then detecting high frequency transition components in the corresponding luminance signal. These luminance signal high frequency components are then added to the switching signal in a manner that insures that their polarities match, thereby generating a higher bandwidth chroma key switching signal. This resultant higher bandwidth chroma key switching signal is used to control cross fade amplifiers which function to output either the video signals of a first or a second scene with linear transitions between these video signals during switching.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.