Paper
8 September 1995 Thermal image calibration: Infracal
Tej P. Kaushal
Author Affiliations +
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.
© (1995) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Tej P. Kaushal "Thermal image calibration: Infracal", Proc. SPIE 2552, Infrared Technology XXI, (8 September 1995); https://doi.org/10.1117/12.218225
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KEYWORDS
Calibration

Thermography

Atmospheric optics

Imaging systems

Atmospheric sensing

Sensors

Radiometry

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