1. A method of classifying at least a portion of a target image using a digital processor and a directory of image examples, comprising: processing image examples with the digital processor and deriving therefrom a set of component vectors; using vectors from the set of component vectors to select a set of basis vectors; and using the digital processor to compare at least one vector in the set of basis vectors against the target image to yield comparison results and classifying portions of the target image in dependence upon the comparison results; wherein selecting basis vectors includes using the digital processor to perform an operation upon at least some vectors to determine strength of correlation with image examples in the directory, using the digital processor to perform an operation upon at least some vectors to determine strength of correlation with smooth image transitions, responsive to the operations, selecting the set of basis vectors to include only vectors which relatively weakly correlate with image examples in the directory and which relatively strongly correlate with smooth image transitions.