Effective surface brightness as a function of effective radius (Kormendy 1977 relation) drawn by Bai et al. (2014) for BCGs at various redshifts. We use their Fig. 7 as a reference, where the shaded region (here drawn with small dotted vertical lines) indicates a size that is larger than the BCG images that they used in their study; the black solid line shows the slope of the constant magnitude relation (indicated with an arrow); the other black line is the best fit to their BCG sample; the dotted line is for local BCGs and the dashed line is the best fit for the lower-mass ETGs. We superimpose as blue stars our values for the Sérsic outer component (all our objects were observed in the F814W filter except one).