Abstract: A method for determining region boundaries in an image comprises the steps of providing an image having a plurality of discrete points, determining for each discrete point in the image an affinity force vector representing the affinity of the point to every other point in the image, and detecting region boundaries in the image using the affinity force vectors. An apparatus for determining region boundaries in an image comprises means for providing an image having a plurality of discrete points, means for determining for each discrete point in the image an affinity force vector representing the affinity of the point to every other point in the image, and means for detecting region boundaries in the image using the affinity force vectors. Automatic spatial parameter selection for input in the affinity force vector determination and regional axis detection methods are also provided.