Comprehensive electronic compositing system
US4344085A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Dec 4, 1980 |
| Grant date | Aug 10, 1982 |
| Priority date | — |
| Expiry date | Dec 4, 2000 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N9/75
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
The linear foreground and background compositing system of the "blue-screen" type and as included in my prior U.S. Pat. No. 4,100,569, is provided with non-linear background control signals for improved composite picture quality under various adverse circumstances. More particularly, the problem of footprints, scuff marks, and dust on the "blue-screen" background for the foreground signal has been eliminated by a "clean-up" circuit 98 which shifts the background signal to "fully on" when it reaches a level in the vicinity of 80 or 90 percent "on", and making a concurrent reduction in the foreground signals, so that above the selected control level shadows or semi-transparency objects are made fully transparent and are not reproduced. The problem of "print-through" in the case of glossy black objects has been avoided by a circuit 34 which reduces background signal to zero when the level of blue foreground signals drops below a predetermined level. The problem of shadow inversion and high noise level which may arise when foreground objects are subject to back lighting has been solved by the use of a dual control signal, one operating in the blue backing area, and the second operating…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.