Illustration of the effect of spectral resolution and photon noise on the quality of the inversions. The left-hand mosaic shows the results of the inversion after spectral degradation of the line profiles with a Gaussian instrumental profile with FWHM = 50 mÅ, the right-hand panel after smearing with a profile with a FWHM of 100 mÅ. Within each mosaic, from left to right, the panels show B_z(x,y),|B_x(x,y)|,|B_y(x,y)|. Rows, from top to bottom, show the magnetic field from the 3D snapshot, followed by the inversion results assuming random photon noise of σ = 0, σ = 10^-4, σ = 10^-3.5 and σ = 10^-3.