Hsiao-Yun Huang Bor-Chen Kuo Hsiang-Chuan Liu Yu-Lung Liu SLEX-NWFE feature extraction method for hyperspectral image classification. 3210-3214 2007 IGARSS http://dx.doi.org/10.1109/IGARSS.2007.4423528 conf/igarss/2007 db/conf/igarss/igarss2007.html#HuangKLL07