An unsupervised change detection algorithm for multi-temporal satellite images based on principal component analysis(PCA) and up-down-set fuzzy Kohonen clustering network(UDSFKCN) is proposed in this paper.This method generated eigenvector corresponding to every pixel combining itself with its neighbours using principal component analysis.At the same time,the detection of the changed pixel in a region was converted into the classification between two groups,changed group and unchanged group.Sinc...