Method for mismatch detection between the frequency of illumination source and the duration of optical integration time for imager with rolling shutter
US7142234B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Dec 10, 2002 |
| Grant date | Nov 28, 2006 |
| Priority date | — |
| Expiry date | Nov 1, 2024 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N23/73
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A method for achieving flickerless operation of imagers using a rolling shutter, including the steps of detecting flicker in an image frame and adjusting an integration time such that the integration time is an integer multiple of a light intensity period, is described. The method reduces the task of detecting flicker to detecting a spatial sine wave in the image frame by subtracting two image frames from each other. The subtraction reduces or eliminates image content from the image frames and makes the detection process independent of image content. This method can be practiced based on a very short sequence of image frames (as few as two image frames) and is virtually insusceptible to motion of the image content. Adjustments to the integration time are made by changing the horizontal blanking time of the imager and, thereby extending the duration time of each row of said image frame.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.