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Hyperspectral-based automatic target recognition (ATR) and classification systems often project the high-dimensional hyperspectral reflectance signatures onto a lower dimensional subspace using techniques such as principal component analysis, Fisher's linear discriminant analysis (LDA), and stepwise LDA. In a general classification framework, these projections are suboptimal and, in the absence of sufficient training data, are likely to be ill conditioned. In recent work, the authors proposed a divide-and-conquer approach that partitions the hyperspectral space into contiguous subspaces followed by a multiclassifier and decision-fusion (MCDF) framework. Although this technique alleviated the small-sample-size problem and provided a good recognition performance in light and moderate pixel mixing, the performance significantly decreased under severe mixing conditions, as it does with conventional ATR techniques. In this letter, the authors propose a kernel discriminant analysis-based projection in each subspace of the partition, followed by the MCDF framework to ensure robust recognition even in severe pixel-mixing conditions. The performance of the proposed system (as measured by overall recognition accuracies) is greatly superior to conventional dimensionality-reduction techniques as well as the more recently proposed LDA-based MCDF technique.
Date of Publication: July 2009