A new multiscale wavelet transform algorithm for dim target detection in forward looking infrared (FLIR) imagery is described. The algorithm was evaluated using a database of FLIR image sequences representing different target, sensor, and background clutter scenarios. Detection performance was quantified in terms of the receiver operating characteristics (ROC) for all sequences. The detection performance of the new algorithm was compared to the Holmes double-gated filter method and was found to be comparable or significantly better depending on the image sequence.
This paper describes a new wavelet-transform-based nonlinear spatial filter called the scale subtraction filter (SSF). The SSF enhances dim target signals relative to clutter in forward- looking infrared (FLIR) imagery using the scale characteristics of the target. The SSF was applied to a database of FLIR image sequences representing different target, sensor, and background clutter scenarios. Detection performance was quantified in terms of the receiver operating characteristics (ROC) for all sequences. The detection performance of the new algorithm was compared to the Holmes double-grated filter method and was found to be equivalent or significantly better depending on the image sequence.
This paper presents a sea radiance polarization model and experimental measurements of near- horizon sea glint polarization in the 3 - 5 micrometers and 8 - 12 micrometers spectral bands. The experimental measurements include the effects of polarization on the glint statistics, the degree of linear polarization and the polarization signal-to-noise ratio (SNR) improvement factor for both spectral bands in the presence of sea glint. The results indicate that the polarization in the 3 - 5 micrometers spectral band is dominated by the reflected solar and sky radiance and is polarized in the s plane. The polarization of intense sea glint in the 8 - 12 micrometers region is low and s polarized due to the weak solar spectrum in this band. In little or no glint, the radiation is weakly p polarized. Experimental data indicate that a polarizing filter can produce a significantly larger SNR improvement for the 3 - 5 micrometers spectral band than for the 8 - 12 micrometers band. Theoretical calculations using the polarization model show good agreement with the experimental data.
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