Measured diameter d, width w, position angle, and fractional central brightness f_C of M87^*, measured from image reconstructions assuming different total compact flux densities, F_cpct for DIFMAP (orange), eht-imaging (blue), and SMILI (green) (see Sect. 5.3). All measurements are made using REx. All other imaging parameters were set to the fiducial parameters of the corresponding pipeline. DIFMAP values were measured after restoring with a 20 μas FWHM Gaussian beam. The solid lines indicate the measured value, and the shaded regions give the ±1σ uncertainty of the REx measurement. The darker colored regions correspond to values of F_cpct that produces images that have (1) normalized ,   (with 10% systematic uncertainty for DIFMAP), and (2) a corresponding self-calibration solution with 0.9 ≤ median(1/|g_SMT|) ≤ 1.1.