Determination of optimal SExtractor parameters. Upper panel: selection of tested SExtractor parameter sets. Colored curves show SExtractor detection number counts for different setups (TH: detection threshold; A: minimum area of pixels above threshold; DBTH: number of deblending subthreshold; DBCONTR: deblending contrast). The black, dashed histogram indicates the number of simulated galaxies in each magnitude bin. The red solid line represents our final choice, since it provides an optimal balance between the fraction of recovered objects and the detection of spurious ones. Lower panel: the red, solid histogram shows the fraction of recovered simulated galaxies using the optimal parameter set. The black solid line is a fit to the red histogram (i.e., our completeness function). Owing to crowding incompleteness (high foreground star density), the recovery completeness saturates at 80% for the brightest sources.