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Proceedings Paper

A look at non-uniformity correction in the spatial frequency domain
Author(s): Guy Raz; Yuval Weiss
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Paper Abstract

The residual non uniformity of IR detectors is of major concern in the implementation of innovative IR systems. Several algorithms were developed during the last decade in order to solve this problem. One of these algorithms, "Scene based non uniformity correction" (SBNUC), is based on the notion that for a moving thermal imager, close by pixels get over time similar distributions of scene radiation. Following this assumption, differences between the time collected histograms of pixels are due to non uniformity and can thus be corrected. However, pixels which are not in the closest proximity of each other need in general more time for their histograms to match. Moreover, depending on the imager motion characteristics, there can be additional temporal and spatial limitations. An efficient SBNUC algorithm must take the exact limitations into consideration. In this work the SBNUC spatial-temporal relations are investigated using the spatial frequency domain representation. This representation provides an effective point of view since distances in the image are naturally translated into different spatial frequencies. We show that a way to implement this correction by a recursive time filter incorporates spatial frequency dependence into the correction speed, allowing the spatial-temporal relation to be engineered easily into the correction process. Using several characteristic imager motion models we analyze the effect of the motion on the spatialtemporal relations and demonstrate how an optimal SBNUC process can be designed, for each motion model.

Paper Details

Date Published: 21 May 2011
PDF: 12 pages
Proc. SPIE 8012, Infrared Technology and Applications XXXVII, 80123Q (21 May 2011); doi: 10.1117/12.883937
Show Author Affiliations
Guy Raz, Elbit Systems Electro-Optics El-Op Ltd. (Israel)
Yuval Weiss, Elbit Systems Electro-Optics El-Op Ltd. (Israel)

Published in SPIE Proceedings Vol. 8012:
Infrared Technology and Applications XXXVII
Bjørn F. Andresen; Gabor F. Fulop; Paul R. Norton, Editor(s)

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