High speed analog color key detection technique and system
US6169533A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Apr 25, 1997 |
| Grant date | Jan 2, 2001 |
| Priority date | — |
| Expiry date | Apr 25, 2017 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG09G2340/125
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A high speed analog color key detection system is disclosed for video/graphics mixing that employs a high speed analog strobe comparator to compare the analog version of a pre-defined color key value to the stream of pixel values in an incoming analog graphics signal. When the comparator indicates a match, the display signal is switched from the analog graphics signal to an incoming analog video signal, enabling the analog video signal to be displayed within a graphics window. Comparisons are triggered by active transitions of a strobe signal with a frequency that is an integer k multiple of the frequency at which the pixel values are generated by a graphics card. Oversampling strobe signals (where the integer k is greater than one) enable comparisons to be performed on small segments of fat pixel values. The strobe signal is generated using a phase locked loop that is synchronized with a horizontal synchronization signal provided by the graphics card. The PLL also regenerates the pixel clock using the horizontal synchronization signal.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.