Galfit fitting of the star-forming knots reported in Table 1 zooming on various regions (groups A, D, G, H and L, see Fig. 2). Left column: original F555W image, in which only the knots listed in Table 1 are marked with their IDs. Middle column: Galfit models and right column: residual after subtracting the models, with the positions of the knots indicated as in the left column. Besides the IDs in the reference sample (marked in blue), additional multiply imaged knots have been modeled, such as the cloud of clusters of the group D (see the same group described in Fig. 2). All knots are not resolved with resulting effective radii ≲1 pixel, independently from the Sérsic index (n = 0.5 − 4).