Image contrast enhancement sometimes complicates image understanding. A scene that consists of slightly dissimilar target and background emittances may not be readily identifiable without image enhancement. Even if the emittance differential can be sharply contrasted, those image surface patterns that convey subsurface thermal information may not be visible because of the wide dynamic range that must be accommodated by the thermal imaging system. This paper describes how emittance complicates the interpretation of thermal images. High and low emittance values affect the logic required for understanding thermal scenes. Thermal scenes containing emittance differentials are easier to interpret if there is a large contrast between the object and the background.
R. H. Munis,
S. J. Marshall,
"Emittance: A Little Understood Image Deception In Thermal Imaging Applications", Proc. SPIE 0549, Image Quality: An Overview, (2 July 1985); doi: 10.1117/12.948807; https://doi.org/10.1117/12.948807