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Proceedings Paper

Continuous Luminance Pseudocolor Mappings For Infrared Thermography
Author(s): Paul Hughett
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Paper Abstract

A suitably-calibrated infrared thermogram contains both qualitative information about the temperature distribution and quantitative information about the numerical temperature valhes. A grey-scale rendering shows the temperature distribution well for human interpretation but cannot be used to obtain numerical values. Conversely, a density-sliced pseudocolor rendering permits semi-quantitative interpretation but often obscures fine details of the temperature distribution. A single rendering which provides both would be useful. Color perception includes the three distinct dimensions of brightness, hue, and saturation; these may vary independently. It is thus possible to construct a pseudocolor mapping in which brightness varies continuously but hue and saturation vary stepwise. If applied to a thermogram, the result is a grey-scale image with superimposed color tints organized into contours. The grey-scale image shows the temperature distribution clearly, and the tints correspond to temperature contours for semi-quantitative interpretation. The grey-scale image may be enhanced before temperature contours are applied. Point operations such as contrast stretching or histogram equalization increase visibility of detail but retain a one-to-one correspondence between grey level and temperature. Neighborhood operations such as unsharp masking or gradient filtering are also possible. These operations destroy the one-to-one correspondence so temperature contouring becomes essential to portray even semi-quantitative temperature information.

Paper Details

Date Published: 21 March 1989
PDF: 10 pages
Proc. SPIE 1094, Thermosense XI: Intl Conf on Thermal Infrared Sensing for Diagnostics and Control, (21 March 1989); doi: 10.1117/12.953402
Show Author Affiliations
Paul Hughett, Hughett Research (United States)

Published in SPIE Proceedings Vol. 1094:
Thermosense XI: Intl Conf on Thermal Infrared Sensing for Diagnostics and Control
Gregory B. McIntosh, Editor(s)

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