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Improving Wishart Classification of Polarimetric SAR Data Using the Hopfield Neural Network Optimization Approach
Software Engineering and Artificial Intelligence, Faculty of Informatics, University Complutense of Madrid, 28040 Madrid, Spain
Remote Sensing Laboratory (RSLab), Signal Theory and Communications Department (TSC), Universitat Politècnica de Catalunya (UPC), 08034 Barcelona, Spain
Technical University of Madrid, Campus SUR, Ctra. de Valencia, km.7, 28031 Madrid, Spain
* Author to whom correspondence should be addressed.
Received: 30 September 2012; in revised form: 14 November 2012 / Accepted: 16 November 2012 / Published: 19 November 2012
Abstract: This paper proposes the optimization relaxation approach based on the analogue Hopfield Neural Network (HNN) for cluster refinement of pre-classified Polarimetric Synthetic Aperture Radar (PolSAR) image data. We consider the initial classification provided by the maximum-likelihood classifier based on the complex Wishart distribution, which is then supplied to the HNN optimization approach. The goal is to improve the classification results obtained by the Wishart approach. The classification improvement is verified by computing a cluster separability coefficient and a measure of homogeneity within the clusters. During the HNN optimization process, for each iteration and for each pixel, two consistency coefficients are computed, taking into account two types of relations between the pixel under consideration and its corresponding neighbors. Based on these coefficients and on the information coming from the pixel itself, the pixel under study is re-classified. Different experiments are carried out to verify that the proposed approach outperforms other strategies, achieving the best results in terms of separability and a trade-off with the homogeneity preserving relevant structures in the image. The performance is also measured in terms of computational central processing unit (CPU) times.
Keywords: Hopfield neural networks; image classification; Polarimetric Synthetic Aperture Radar (PolSAR); Wishart classifier; optimization
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Pajares, G.; López-Martínez, C.; Sánchez-Lladó, F.J.; Molina, Í. Improving Wishart Classification of Polarimetric SAR Data Using the Hopfield Neural Network Optimization Approach. Remote Sens. 2012, 4, 3571-3595.
Pajares G, López-Martínez C, Sánchez-Lladó FJ, Molina Í. Improving Wishart Classification of Polarimetric SAR Data Using the Hopfield Neural Network Optimization Approach. Remote Sensing. 2012; 4(11):3571-3595.
Pajares, Gonzalo; López-Martínez, Carlos; Sánchez-Lladó, F. J.; Molina, Íñigo. 2012. "Improving Wishart Classification of Polarimetric SAR Data Using the Hopfield Neural Network Optimization Approach." Remote Sens. 4, no. 11: 3571-3595.