Dynamic video scrambling
US4454543A · kind A · utility
107Cited by
6References
4Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Nov 6, 1981 |
| Grant date | Jun 12, 1984 |
| Priority date | — |
| Expiry date | Nov 6, 2001 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N7/171
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A means for coding and decoding video signals by the application of one of a plurality of available scrambling signals includes means for comparing the brightness level during a predetermined time period of the video signal with the brightness level of the video signal over the succeeding predetermined time period. There are means for changing from one scrambling signal to another if the difference between brightness levels in successive predetermined time periods exceeds a given value.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.