Abstract Pavlidis in his “analysis of set patterns” proposed three size-oriented similarity measures. In this paper, shape-oriented similarity and dissimilarity measures of triangles and polygons are proposed and investigated. There are three advantages of shape-oriented similarity measures. First, two polygons may have the same shape but differ in area and dimensions and still be similar. Second, shape-oriented similarity and dissimilarity measures can be normalized between zero and one. Third, shape-oriented similarity measures are invariant with respect to rotation, translation, or expansion or contraction in size. The “rubber-mask” technique proposed by Widrow utilized length and width parameters in the classification of chromosomes. In this paper, chromosome images are classified through the use of angular and dimensional proximity measures which are in terms of angle and length parameters. The results obtained in this paper may contribute to processing a picture from the polygonal approximation stage to the final filtering stage in order to recognize or classify a picture.