"Video system with feedback controlled ""white stretch"" processing and brightness compensation"
US5191420A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 16, 1991 |
| Grant date | Mar 2, 1993 |
| Priority date | — |
| Expiry date | Dec 16, 2011 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N5/20
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A non-linear (e.g., "white stretch") processor and a brightness control processor are coupled in cascade between an input for receiving a video input signal to be processed and an output for providing a processed video output signal. A control signal for controlling the transfer characteristics of the non-linear processor is provided by an amplifier having a first input coupled to receive an average picture level (APL) indicating signal derived from the processed video output signal and having a second input coupled to receive a reference level signal supplied thereto. A brightness control signal is applied to a control input of the brightness control processor for controlling the brightness level of the processed video output signal. Circuit means are provided for deriving at least a portion of the reference level signal for the amplifier from the brightness control signal supplied to the brightness control processor thereby reducing a tendency for variations in the brightness control signal to alter the transfer characteristics of the non-linear processor.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.