Same as Fig. A.1, but for a stellar density of 10⁴ stars arcsec⁻². At these densities, the number of double stars has increased to the point where our detection algorithm was unable to accurately fit and subtract many of the bright stars. Although a large number of incorrect mass determinations are visible in the large blue cloud, about 60% of the ∼40 000 sources in this image still fall on the red one-to-one line. The segmented PSF meant that the algorithm detected many false sources, which skewed the detection statistics in both the high- and low-mass regimes. We are still investigating ways of preventing this from happening in future studies.