1. An image processing method comprising the steps of artificially generating, by a computer, a normal structure element image representing a normal structure of at least one predetermined structure element included in an object by preparing a statistical model of the structure element from teacher data extracted from different normal images of the same kind of object, and generating a structure-removed image, which is an image obtained by removing the predetermined structure element from the image of the object, by an image operation between the image of the object and the normal structure element image of the predetermined structure element, wherein the generating a normal structure element image comprises: obtaining image data representing an image representing normal structure of a structure element the same in kind as the predetermined structure element, setting a plurality of structure change vectors for changing the structure of the structure element of the same kind, and adding the structure change vectors to the image data.