Density of the median G-band magnitude dependence of a_G, the amplitude of the small-separation binary model fit to the G-band photometry (Eq. 5). The top left inset images shows the same data colour-coded with the median r_ipd, G and r_exf, G, respectively, both ranging between 0 (blue) and 1 (red). See Sect. 6.3 for discussion. Plots are restricted to sources with N_3band ≥ 20 and N_noEpsl, G ≥ 20.