Comparison of injected and recovered flux densities. Upper row: distribution of the normalized difference (Eq. (B.1), blue contours, [68, 95, 99]%) versus NPSNR for three different data sets (from left to right): PCCS2 “same location”; PCCS2 “neighbourhood”; and PCCS2E ∧ |b| > 10° “neighbourhood”. The red contours show the same as the blue ones, but this time for corrected values (Eq. (B.5)). The horizontal dashed lines are ±3 σ. Lower row: identical flux-density relative error (ΔSREF/SREF) distribution contours. The black dashed lines here are NPSNR⁻¹, the lower limit of the flux-density relative error, which is only achievable if the only unknown parameter in the model is the flux density.