Apparatus, systems, and methods integrating spectral information with spatial feature extraction of image data, providing simultaneous spatial and spectral feature selection of the image data, can be used in a variety of applications. In various embodiments, an edge signature for the edge between two materials can be defined using ratios of identified spectral bands, where the edge signature can be combined with a spatial mask to obtain a joint spatio-spectral mask. Additional apparatus, systems, and methods are disclosed.