1. A method for the automated analysis of a digital image comprising an array of pixels, including the steps of: (a) identifying the locations of objects within the image which have specified intensity and size characteristics; (b) defining regions of specified extent within the image which contain respective said objects; (c) deriving from the data within respective said regions one or more respective closed contours comprising points of equal intensities; and (d) estimating the curvature of at least one respective said contour within respective said regions at least to produce a measure of any concavity thereof.