1. A method for reconstructing an image of a subject from undersampled image data, the steps of the method comprising: a) acquiring, with an imaging system, undersampled image data from a subject; b) reconstructing from the acquired undersampled image data, an image of the subject; c) producing from the image of the subject, a number of similarity clusters; d) processing the similarity clusters; e) producing a number of weighting values that are related to the processing used in step d); and f) producing a target image of the subject using the processed similarity clusters and the number of weighting values.