1. A method of comparing at least two sets of multimedia data using shape information so as to provide a dissimilarity measure between the sets, a first set forming a reference set and the second set being compared relative to the first set, the method comprising steps of; a) providing a set of approximately equidistant contour points for each set of multimedia data, b) associating the contour points of the first set with contour points of the second set so as to define associated contour points, c) calculating distances between said associated contour points, and wherein the distances between said associated contour points are used to determine a dissimilarity measure between said sets of multimedia data, thereby providing an indicator of the degree of similarity between the sets.