1. A method of operating an image interpretation system wherein an object in the image is automatically detected, the method comprising the steps of: digitizing the image; inputting the digitized image into a data processing means; detecting automatically the object using the data processing means and the digitized image comprising the steps of: forming a contour plot of the image, the object in the contour plot comprised of a set of nested contour lines wherein the contour lines correspond to intensity levels thereby causing the object to appear as a peak in relation to the surrounding background in the image; obtaining a sequence of contour areas from the set of nested contour lines progressing from the contour line having the highest intensity level to the contour line having the lowest intensity level; computing a feature of the set of nested contour lines using the sequence of contour areas; and detecting the object using the computed feature; and indicating the location of the object in the image.