Colour maps for the reference galaxy when applying different masks (r₁, r₂): the 90% percentile of the relative error in panel (A), up to ε_rel, 90% ≥ 10%; the 90% percentile of the relative standard deviation in panel (B), up to σ_fit, 90% ≤ 2%; the relative 90% width of the ${\overline{N}}_{\mathrm{fit}}$ distribution in panel (C), up to Δ_90% ≤ 10%; and the number of pixels within each one of the masks (n_mask pix) in panel (D). The contour lines found over the map in panels (A), (B) and (C) correspond to the number of pixels shown in panel (D). The black circled-cross signals the reference galaxy presented in Sect. 2.1 with the mask applied in its source reference Cantiello et al. (2018); r₁ ≈ 80 px, r₂ ≈ 332 px).