Mapping localized spectral features in large images demands sensitive and robust detection algorithms. Two aspects of large images that can harm matched-filter detection performance are addressed simultaneously. First, multimodal backgrounds may thwart the typical Gaussian model. Second, outlier features can trigger false detections from large projections onto the target vector.

Two state-of-the-art approaches are combined that independently address outlier false positives and multimodal backgrounds. The background clustering of Funk et al. models multimodal backgrounds, and the mixture tuned matched filter (MT-MF) of Boardman et al. addresses outliers. Combining the two methods captures significant additional performance benefits. The resulting mixture tuned clutter matched filter (MT-CMF) shows effective performance on simulated and airborne datasets.

The classical MNF transform was applied, followed by k-means clustering. Then, each cluster’s mean, covariance, and the corresponding eigenvalues were estimated. This yields a cluster-specific matched filter estimate as well as a cluster- specific feasibility score to flag outlier false positives.

The technology described is a proof of concept that may be employed in future target detection and mapping applications for remote imaging spectrometers. It is of most direct relevance to JPL proposals for airborne and orbital hyperspectral instruments. Applications include subpixel target detection in hyperspectral scenes for military surveillance. Earth science applications include mineralogical mapping, species discrimination for ecosystem health monitoring, and land use classification.

This work was done by David R. Thompson, Lukas Mandrake, and Robert O. Green of Caltech for NASA’s Jet Propulsion Laboratory. For more information, contact This email address is being protected from spambots. You need JavaScript enabled to view it.. NPO-48663

NASA Tech Briefs Magazine

This article first appeared in the March, 2013 issue of NASA Tech Briefs Magazine.

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