This new edition updates the technologies that deal with the characterization of the thermal infrared radiation contrast between ground targets and backgrounds. Samples have been updated to comply with the current status of technology in sensor systems and countermeasures. New topics on mine detection and polarization have been included, and the section covering multispectral camouflage of personnel has been extended. The basic principles and meteorological parameters are presented, followed by calibration procedures, signature measurements, and data analyses.

The number of stimulus colors which can be absolutely identified by normal subjects when viewed against various colored backgrounds was investigated. Additive mixtures of light passed through narrow-band and Illuminant-C filters were projected onto a viewing screen by a device wich permitted independent control of target and background characteristics. The stimulus parameters of hue, luminance, purity, target size, and target shape were varied, and the effects of such factors as training and the presence of a distracting task were studied. With target luminance above background luminance, about nine hues plus white, three luminance levels, and two purity levels, are estimated to be useful for operational coding, if no more than about 30 of the possible combinations are included in the set. Under optimal working conditions and with protracted training, the maximum size of an identifiable set is estimated to be about 60. Reduction of target luminance below the luminance of a colored background was found to make identification very difficult. No significant effect of target shape was found. (Author).