Relative differences of ⟨B_LOS⟩, in %, between the 5250.2 and 6173.3 Å spectral lines. From the top left panel clockwise: for ⟨B_Z⟩ = 30, 50, 100, 200 G respectively. At each μ the retrieved ⟨B_LOS⟩ quantities are averaged over all snapshots and viewing directions. The shaded regions denote the propagated standard deviation of the difference. The y axis is saturated from −20% to +30%. The legend in the upper left panel is valid for all panels. The dashed black line indicates the zero level.