Imaging apparatus offering dynamic range that is expandable by weighting two image signals produced during different exposure times with two coefficients whose sum is 1 and adding them up
US6677992B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Oct 22, 1998 |
| Grant date | Jan 13, 2004 |
| Priority date | — |
| Expiry date | Oct 22, 2018 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N23/555
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An object is imaged continuously during a first exposure time and a second exposure time shorter than the first exposure time. Weights, one of which decreases monotonously and the other of which increases monotonously, are applied to first and second resultant image signals under the condition that the sum of the weights is 1. The first and second image signals that have been weighted are added up, thus producing a synthetic picture signal. When a luminance level is low, the ratio of the first image signal, which has been produced during the longer exposure time, to the second image signal is increased. This results in an image demonstrating a high signal-to-noise ratio. When the luminance level is high, the ratio of the second image signal, which has been produced during the shorter exposure time, to the first image signal is increased. This results in a synthetic image that proves a wide dynamic range, depicts a smoothly varying brightness level, and exhibits a characteristic of being seen as almost natural. Moreover, the first and second image signals are produced to resemble those produced during mutually different exposure times by controlling an amount of light incident on an…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.