Minor-axis g- and i-band surface-brightness profiles versus the vertical distance z of the LSBG model. Panels and lines are as described in Fig. 2. Circles (crosses) indicate measured values of the g band (i band; BZC10). In panel a), the blue and the red solid lines that are overstriked with a white solid line show the PSF-affected input model. In panel b), the corresponding g − i colour measurements are shown with crossed circles, and the thick overstriked line shows the colour of the PSF-affected model.