Multimarginal Wasserstein Barycenter with 1, 2, and 3 reference images, i.e., N = 2, 3 or 4 in (6). The images with blue borders are input/source images, the ones with green are the (intermediate) references and the red ones are the final reference/target images. Reference images can be from the same or different domains. Ideally in the multimarginal case, one of the intermediate references should have some background.