Image scanning signal generating apparatus with pre-scan for exposure control
US4651226A · kind A · utility
Assignees
Inventors
Key dates
| Filing date | Oct 17, 1984 |
| Grant date | Mar 17, 1987 |
| Priority date | — |
| Expiry date | Oct 17, 2004 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N1/4072
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An image signal generating apparatus includes an optical system for focusing the image of a photographic film onto a predetermined plane and a scanning device for scanning the image with a photoreceptor positioned at the predetermined plane and generating output signals representing the light intensity distribution of the film. The scanning device performs a first scan of the image and a second scan of the image upon completion of the first scan. During the first scan the levels of the output signals indicative of the maximum density and the minimum density of the film are detected, and during the second scan the exposure of the photoreceptor is controlled in accordance with the detected levels. Also, during the second scan, the output signals are clamped to a clamp level calculated in accordance with the detected maximum density level and the minimum level of the output signals during the first scan.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.