Abstract: In a diagnostic process in which two images are made on an image recording medium of the same structure at the beginning and the end of a time interval during which the structure changes, a method is provided for permitting a computing device to improve the alignment of the images as reproduced in the form of pixels on a monitor screen. A particular spatial pattern of marker elements is provided, when each of the images is made, in a particular juxtaposition to the structure being imaged, so that the shadows of the elements arise on the respective images. The computing device can then rotate, translate and alter the scale of one image with respect to the other until the shadows of the elements on one image coincide as closely as possible with those on the other image.