Bin-averaged continuum intensity contrast near 630 nm vs. magnetic field strength. The bin size is 25 G. Shown are observational Hinode/SP data (red curve), simulation data (intrinsic vertical field) at original resolution (solid black curve, values taken at optical depth 0.1), inverted apparent magnetic field at original simulation resolution (dashed black curve), and synthetic Hinode/SP observations derived from the simulations (green curve). The shift between the solid and dashed black curves (the inverted field being somewhat weaker than the original field for the same contrast value) indicates that the inversion effectively samples the magnetic field at a level somewhat above the surface of optical depth 0.1.