Our bubble detection process: create a Minkowski map by calculating marching-square maps at different thresholds (step 1), averaging them (step 2), and smoothing with a desired window size (step 3). For a ψ₂ Minkowski map at one window size, draw lines perpendicular to filaments using arg(ψ₂), whose length is proportional to |ψ₂| and a chosen length factor (step 4). Counting the lines in each position gives a line density map. By choosing a suitable threshold here, we obtain the position of the bubble candidates (step 5). Then, |ψ₂ | at the bubble positions should decrease for bubbles standing alone and rise at least not significantly if there are neighboring structures. This is checked by comparing to a Minkowski map at a suitable larger window size (step 6).