1. A computer-implemented method comprising: determining an image pyramid from an input image, the image pyramid comprising a sequence of successive images, wherein each of the successive images has a respective spatial resolution that is higher than that of the preceding image in the sequence; filtering a selected one of the successive images to produce a filtered image; ascertaining a comparison image from a comparison of the selected image and the filtered image; correcting a next one of the successive images following the selected image in the sequence based on the comparison image to produce a corrected image; and repeating the filtering with the corrected image as the selected image.