Radial R-band and i-band surface-brightness profiles versus radius for three face-on disc galaxies: a) and b) NGC 4477; c) and d) NGC 3507; and e) and f) NGC 2880. The panels, lines, coloured bullets, and offsets are as described in Figs. 2 and 4. Diamonds (crosses) show R-band SDSS (INT) measurements (EPB08, their Fig. 14); red symbols indicate values that are fainter than their sky-uncertainty limit.