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Proceedings Paper

Noise and artifact reduction in infrared thermography
Author(s): Paul Hughett
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Paper Abstract

An infrared scanner which is good for visual inspection is not always suitable for image processing applications. Noise and artifacts which are inconspicuous in continuous video can become objectionable when a single frame is digitized, processed and displayed. Fortunately, image processing can often be used to reduce or eliminate the artifacts. Signal noise and video interference can be reduced by a spatial lowpass filter; the filter can be tuned to the interference frequency to eliminate it completely. Digitizing an interlaced scan of a rapidly-changing scene effectively superimposes two images at slightly different instants; this image can be split into two images with reduced spatial resolution but twice the time resolution. The use of an oscillating mirror for scanning can introduce a ragged appearance on edges in the scene; this artifact can be greatly reduced by a suitable filter design. If the images are to be used for quantitative temperature or radiance measurements, then care must be taken to ensure that the filter algorithms do not introduce any systematic bias or distortion and that they do not move significant peaks and edges in the image. It is shown that a linear filter is well-behaved in this sense provided that its impulse response is localized, even, and has unit area. A filter matched to the characteristics of a specific equipment configuration was designed, implemented, and tested on sample images from that equipment. Selected sample images are shown before and after processing.

Paper Details

Date Published: 1 March 1990
PDF: 8 pages
Proc. SPIE 1313, Thermosense XII: An International Conference on Thermal Sensing and Imaging Diagnostic Applications, (1 March 1990); doi: 10.1117/12.21950
Show Author Affiliations
Paul Hughett, Hughett Research (United States)

Published in SPIE Proceedings Vol. 1313:
Thermosense XII: An International Conference on Thermal Sensing and Imaging Diagnostic Applications
Sharon A. Semanovich, Editor(s)

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