Open Access

Fig. 4.


Flowchart of the clumpiness estimation procedure for one galaxy in our sample (ID 412250): (1) original HST F814W cutout image; (2) segmentation image identifying the galaxy contours; (3) original minus smoothed image, enhancing the visibility of high spatial frequency components; (4) clump detection after applying a 5σ threshold; (5) nuclei visual identification; (6) residual image after clumps light subtraction, which appear as black regions superimposed to the original galaxy image. This figure highlights the power of our approach. We are able to detect clumps very close to the nucleus that would instead have been removed by masking systematically a circular region around the center. It shows also the important role of the deblending function to separate multiple clumps based on the presence of multiple peaks in a single segmentation region, as explained in the text. This case additionally illustrates our conservative approach: we select two nuclei in the clumps segmentation map even though we are not sure about the second on the right (which in alternative could be part of a tidal tail).

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