Comparison of adaptive sub-block averaging and old sub-block averaging (fixed sub-block size) in terms of the alignment of rotated gradients and magnetic fields. We use the supersonic simulation A1 at t_r ≃ 0.8 Myr. Panel (a): magnetic field (red segments) predicted by VGT with fixed sub-block size 44 pixels. Panel (b): magnetic field (streamlines) predicted by VGT using adaptive sub-block averaging. Panel (c): magnetic field morphology inferred from synthetic polarization. Panel (d): AM of VGT and actual magnetic field in in terms of various fixed block size.