Showcasing examples of radial profiles, as described in Sect. 3.2, using NGC 720. Top left panel: the 3.6 μm image, with masks shown via the red contours. Bottom left panel: the same image, with 2″ radial bin width, variable PA and ϵ isophotal ellipses overlaid in black. The blue ellipse shows B-band R₂₅ from HyperLEDA, while the two red ellipses show our values of R_25.5, 3.6 and R_26.5, 3.6 (solid and dashed, respectively). Rightmost panels: radial profiles of, from top to bottom: surface brightness, ellipticity, and position angle. The 3.6 μm and 4.5 μm profiles are offset from each other by the amounts shown in the legends to avoid significant overlap. Profiles shown here are truncated in radius compared to those available online, to avoid clutter from poor-quality fits in the far outskirts. Vertical dotted red lines show R_25.5, 3.6.