22. The method according to claim 20, wherein said step of extracting predetermined features comprises: determining, for each region in said digital mammogram of predetermined size corresponding to the location of each pixel in said cluster image, at least two of area, contrast and background values of a signal within each said region.
23. The method according to claim 22, wherein said step of performing at least one predetermined thresholding test comprises: performing an area versus contrast thresholding test to determine, for each signal for which features are extracted, whether that signal corresponds to a false positive microcalcification cluster, and if so, removing from said cluster image that pixel identifying the location of said false positive microcalcification cluster by setting the value of that pixel in the cluster image to a predetermined value.