Effect of the different ingredients of the model (shown on expanded horizontal scale in the left panel). Solid: model fit of the brightness as function of observed flux density B (the dotted line in Fig. 3, Hinode data). Dotted: same if the bright strong field component is omitted from the model. Dashed: same if the weak field component is omitted. Dot-dashed: predicted magnetic brightness if the preference for intergranular lanes were absent.