A method for determining a metric of a feature on a substrate obtained by a semiconductor manufacturing process involving a lithographic process, the method including: obtaining an image of at least part of the substrate, wherein the image includes at least the feature; determining a contour of the feature from the image; determining a plurality of segments of the contour; determining respective weights for each of the plurality of segments; determining, for each of the segments, an image-related metric; and determining the metric of the feature in dependence on the weights and the calculated image-related metric of each of the segments.