Method and apparatus for improving the effects of color burst modifications to a video signal
US6516132B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Jun 19, 1998 |
| Grant date | Feb 4, 2003 |
| Priority date | — |
| Expiry date | Jun 19, 2018 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N2005/91371
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
In the known color stripe process for preventing recording of video signals, the color burst present on each line of active video is modified so that any subsequent video tape recording of the video signal shows variations in the color fidelity that appear as undesirable bands or stripes of color error. This color stripe process is improved by a combination of modifying the phase of the color burst on only part of the color burst. Additional improvements were obtained by incorporating techniques of widening the normal color burst envelope towards the trailing edge of horizontal sync and towards the beginning of active video. These techniques are useful in improving the performance of the color stripe process in both the NTSC and PAL color systems. However, additional improvements are described in the PAL system whereby the phase modifications are controlled so as to avoid disturbing the so-called PAL ID pulse. Such avoidance of the PAL ID pulse improves the playability of the color stripe signal in the PAL format.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.