  We introduce CatSIM, a new similarity metric for binary and multinary two-
and three-dimensional images and volumes. CatSIM uses a structural similarity
image quality paradigm and is robust to small perturbations in location so that
structures in similar, but not entirely overlapping, regions of two images are
rated higher than using simple matching. The metric can also compare arbitrary
regions inside images. CatSIM is evaluated on artificial data sets, image
quality assessment surveys and two imaging applications
