1. A computer-implemented method, comprising: learning representative land features, by a computing system, from multi-band patches or pixels of image data to form a learned feature dictionary; applying representative features from the learned feature dictionary, by the computing system, to image patches or pixels from an image in a sparse fashion to form a sparse representation; clustering the sparse representation of the features in the image, by the computing system, into land cover categories; and performing land cover classification and change detection in the sparse domain, by the computing system, after the image is clustered and outputting results.