Mean effective surface brightness within the effective radius vs. logarithm of the effective radius for bulges and ellipticals. The Kormendy relation is represented by a fit to the elliptical galaxies. The grey shaded region marks the ±2σ boundaries. The only difference between the two panels is the colour coding. The upper panel shows a separation of the bulges by the Sérsic index, the lower panel shows a separation according to the concentration index. The resemblance between the two plots demonstrates the equal usability of the two parameters n_b and C_20,50 for bulge classification.