Subset ellipticity measurements for geometric models (6 out of 42) for all imaging methods. From left to right: groundtruth image of a given geometric model, τ−ξ distribution using Comrade, THEMIS, eht-imaging, SMILI, and DIFMAP for band 4 synthetic data. Each row corresponds to a different geometric model, with the true model shown in the leftmost column. The vertical and horizontal dashed lines in each panel of τ−ξ distribution indicate the true values. The contours denote 68% and 95% confidence intervals. The vertical dashed line shows τ measured with VIDA for the groundtruth model. The gray shaded region spans the range of τ values for the groundtruth model, from the unconvolved case to the convolution of a circular Gaussian of 20 μas FWHM.