Panel a: CLV of the intensity contrast at low (left) and high B (right), at ⟨B⟩_loc ≤ 100 G (solid curves) and ⟨B⟩_loc >  100 G (dotted curves). From top to bottom, we show the values from the continuum (black) and core (red) of the Fe I 6173 Å line and 1700 Å (blue). Panel b: variation in intensity contrast with B about disc centre (left) and near the limb (right), in the same ⟨B⟩_loc ranges. The intensity contrast profiles are derived in the same manner as the corresponding profiles, which were computed taking all available data into account (filled circles, taken from Figs. 2 and 3). As in Figs. 2 and 3, the standard error is negligible because of the size of the data set.