Total raster error correction apparatus and method for the automatic set up of television cameras and the like
US4285004A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 25, 1980 |
| Grant date | Aug 18, 1981 |
| Priority date | — |
| Expiry date | Feb 25, 2000 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N23/10
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A total raster error measurement and correction circuitry, using digital memory means in the camera head for the storage of correction data, corrects spatial scan, shading, etc., errors in a television picture in two dimensions. The basic spatial error correction circuit effectively synthesizes horizontal rate waveforms on a number of discrete lines of the vertical scan. On all scanned lines between discrete lines, a linear approximation between the two discrete waveforms is made to form a vertically continuous waveform. Black and white shading errors are measured by comparing the black and white video levels against respective selected black and white D.C. levels with and without a cap on the camera lens. Gamma correction is provided by comparing the peak black and white levels to derive any gray level errors. The total raster error correction data are retrieved from memory and are applied to given image pickup sensors and corresponding video processing circuits in the camera head system during real time operation.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.