Amount of circular polarization (normalized to the quiet-Sun continuum intensity) generated as a function of the component of the magnetic field vector that is parallel to the observer’s line-of-sight: B_∥ (dashed lines). Amount of linear polarization (normalized to the quiet-Sun continuum intensity) signals generated as a function of the component of the magnetic field vector that is perpendicular to the observer’s line-of-sight: B_⊥ (solid lines). These curves were obtained by performing a synthesis of the Stokes profiles employing different values of B_∥ and B_⊥ and using two different atmospheric semi-empirical models: red for intergranules and blue for granules. The horizontal black lines indicate the 3σ and 8σ levels assuming a noise of σ = 3 × 10^-4 as in our observed maps (Sect. 2).