Effects of the zp-correction for Stokes Q for the PSF_AO convolved RingI60 model with r₀ = 403.2 mas for observations with a coronagraphic mask, indicated by the central hatched area. Panel a shows the convolved signal Q(x, y), b shows the map after a correction based on the halo Q^z3, c shows the map after correction based on the disk plus halo Q^z2+3, and d shows the map after correction based on the disk region Q^z2. The peak Q signal is in all panels between 22 and 23 units with respect to the indicated color scale.