Nonuniformity correction of an imaging sensor using region-based correction terms
US5471240A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 15, 1993 |
| Grant date | Nov 28, 1995 |
| Priority date | — |
| Expiry date | Nov 15, 2013 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N25/674
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A scene based nonuniformity correction method (40) that computes and applies offset correction errors to a video signal corresponding to an image derived from a imaging sensor (11). A video signal derived from the sensor (11) is processed such that a vector representing offset correction terms is formed, and this vector is initially set to zero. Each element in this vector represents a correction term for a particular detector of the sensor (11). The vector is applied to each pixel of the image by a processor (13) as the pixels are read from the sensor (11). To measure the offset error, the image is separated into vertically oriented regions, each comprising a plurality of channels. The average of each channel within a region is computed (42), and a set of region vectors is foraged, such that there is one region vector for each region. Each region vector is then globally high-pass filtered and then edges larger than a predefined threshold are detected (43), and marked (44). Then, each region vector is further separated into sub-regions (45). The isolated sub-regions are locally high-pass filtered. In one embodiment, the correction terms for each vertical region vector are averaged …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.