Flowchart of identifying and masking internal reflections (ghosts). The star’s image (panel a) is divided into quadrants by azimuthal angle (0–90, 90–180, 180–270, 270–360 degrees). The radial profile of different angles is found (in blue, red, green, and purple) and shown in panel b. The quadrant that has a smaller signal-to-noise ratio (in this case the violet one) was chosen to create a 2D circular projection of that profile (panel c). The 2D projection is subtracted from the input, highlighting all problematic signal (including ghosts and wings of fainter stars) in panel d. We detect all of those low signal-to-noise with NoiseChisel in panel e and then mask them in panel f. The pixels that belong to spikes are re-inserted, as described in the text.