Upper panel: distribution of PNe according to whether they belong to the plane or bulge. Lower panel: distribution of colour indices (H − K_s) and (J − H) for the PNe analysed as “galaxy-like” (resolved) by the pipeline, plotted as red circles, point-like sources, plotted as black squares; error bars have been left our for the sake for clarity. The magenta triangles indicate dust emission loci for an emissivity exponent γ = 0 and temperature K (in steps of 100 K, Phillips & Cuesta 1994). Intrinsic stellar indices for MS spectral types (Bessell & Brett 1988) and the O-type from Martins et al. (2005) are shown by green triangles. Finally, the free-free and free-bound emission from hydrogen ions are shown for the range of 8400 to 17 000 K, by the cyan diamond symbols.