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Proceedings Paper

Thermal image calibration: Infracal
Author(s): Tej P. Kaushal
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Paper Abstract

Infracal software allows captured thermal images to be accurately calibrated by using spectral information taken from the imaging system as well as known data on the object and its environment. A pair of internal or external, in-field reference sources are used for calibration. Calibrated images may be scaled and total in-band radiant intensity calculated in a precise waveband, for example, 3.0 - 5.0 micrometer. This allows fairer comparison to be made between measurements obtained from different imaging systems under different environmental conditions. Information used for calibration includes: detector spectral responsivity, scanner spectral transmission, telescope temperature and spectral transmission, reference temperatures and spectral emissivity, object spectral emissivity, background spectral radiance, atmosphere spectral transmission and radiance, linearity of image gray levels and radiance specification band. Infracal is particularly valuable when accurate remote measurements of temperature or radiance need to be made through a poor atmosphere or at long range. It also allows ordinary thermal imagers to be used as imaging radiometers and spectrally recalibrates images obtained from radiometers such as the Agema 900.

Paper Details

Date Published: 8 September 1995
PDF: 5 pages
Proc. SPIE 2552, Infrared Technology XXI, (8 September 1995); doi: 10.1117/12.218225
Show Author Affiliations
Tej P. Kaushal, Defence Research Agency Malvern (United Kingdom)

Published in SPIE Proceedings Vol. 2552:
Infrared Technology XXI
Bjorn F. Andresen; Marija Strojnik, Editor(s)

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