Resolution of structural analysis using image data is improved. A method is provided including the steps of: acquiring data representing measured images and data representing a predetermined number of reference images (S103); generating data representing groups of derived images by changing a relative position of each of the measured images, evaluating similarity between the derived images and the reference images for each group of the derived images, and extracting a plurality of derived images highly similar to any one of the reference images, from each of the groups of the derived images (S105); classifying the extracted derived images into a plurality of groups on the basis of a spatial arrangement of the derived images, averaging the derived images classified into a common group to generate data representing a plurality of averaged images (S107); and determining a structure of a measurement object based on data representing the averaged images (S115).