TARGET ACQUISITION MODELING FOR CONTRAST-LIMITED IMAGING - EFFECTS OFATMOSPHERIC BLUR AND IMAGE-RESTORATION

The incorporation of atmospheric aerosol and turbulence effects into v isible, near-infrared, and thermal-infrared target acquisition modelin g is considered. We show how the target acquisition probabilities and, conversely, the ranges at which objects can be detected are changed b y the inclusion of atmospheric effects. It is assumed that images are contrast limited rather than noise limited, as is indeed the case with most visible, near-infrared, and thermal infrared sensors. For short focal lengths with low angular magnification, atmospheric effects on t arget acquisition are negligible. However, for longer focal lengths wi th large angular magnification, resolution is limited by the atmospher e, and this has a strong adverse effect on target acquisition probabil ities, times, and ranges. The considerable improvement possible with i mage correction for atmospheric blur automatically in a fraction of a second is significant for contrast-limited imaging and is also discuss ed. Knowledge of the atmospheric modulation transfer function is essen tial to good system design and is also useful in image restoration for any type of target or object. Finally, a new target-transfer-function model is suggested that considers the overall image-spectrum target r eceived by the human visual system rather than only the main harmonic detail as in the Johnson chart model. [J. Johnson, in Proceedings of S eminar on Direct-Viewing Electro-Optical Aids to Night Vision (IDA, Al exandria, Va., 1966), p. 177.] (C) 1995 Optical Society of America