In a broadband imaging system, the spectral information from the scene can be as important as the spatial information for the task of discriminating an object or feature of interest (the target) from a backdrop of other objects or features of lesser interest (the background) in the image of the scene. A useful measure of the ability to discriminate a target from its background is the apparent contrast between it and the background. The more diverse the scene is, the greater the apparent contrast can be between objects within the spectral passband of the imager. In broadband imaging, the net spectrally and spatially integrated radiances from a target and its background determine the apparent contrast, which in the reflective bands is a function of the spectra of the target and background reflectivities and the scene illumination. The impact of the scene illumination spectrum on apparent contrast can be significant to the point that a given target will be highly visible against a given background under one illumination source and yet hardly visible under a different source of illumination. This paper examines the impact of the spectral natures of the target, background, and the illumination on intrinsic Michelson contrast and target discrimination with notional reflective broadband imaging systems.

Date Published: 5 June 2013
PDF: 13 pages
Proc. SPIE 8706, Infrared Imaging Systems: Design, Analysis, Modeling, and Testing XXIV, 87060H (5 June 2013); doi: 10.1117/12.2016465

Published in SPIE Proceedings Vol. 8706:
Infrared Imaging Systems: Design, Analysis, Modeling, and Testing XXIV
Gerald C. Holst; Keith A. Krapels, Editor(s)