The present invention includes a method for analyzing an image to screen for target candidates wherein an edge-follower detects straight segments within a plurality of longer edges and detects also from the longer edges, contours that go around areas that are the right size. The invention also contemplates starting the edge-follower from seeds on the image and terminating the edge-following process if the edge meanders too much to ever become an acceptable contour. In accordance with another embodiment, the straight segments can be further screened by measuring the gradient direction and then noting the deviation from the mean of those direction values. The highly straight edges thus found, in confluence with each other, or near a correct size contour define likely candidates.