Analysis of target contrast improvement using polarization filtering in the infrared region
Moretz, David Gavin
Cooper, Alfred William Madison
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Computer analysis with IDL was performed on polarized infrared image data obtained during the MAPTIP coastal experiment. Analysis of contrast enhancement of the oceanographic ship Hr. Ms. Tydeman and a Lynx helicopter using polarization filters is presented. Contrast of vertical and horizontal polarized images was determined by two methods. Unpolarized image contrast was developed from polarization data and used to calculate contrast improvement factors for vertical and horizontal polarizations. Background effects upon contrast were explored. Dependence of projected ship area on contrast improvement was analyzed. Vertical and horizontal polarized images were compared to verify preliminary observations of negligible predominant polarization of man-made targets. Results of this analysis confirm that vertically polarized sea background radiance can be reduced by polarization filtering to enhance ship-to-background contrast. Man-made targets appear to present negligible polarization. Sky background immediately above the horizon also appears unpolarized. Combining radiance from both sky background above the horizon and sea background to form an average background reference radiance reduces overall contrast improvement. Ship-to-background contrast should be calculated with respect to the horizon location.
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