Ellipticity of all 299 GRMHD truths (convolved with 12 μas Gaussian) compared with the non-ring flux fraction. The left and right panels are the same, but the colors are different for (non)thermal models (left) and R_high values (right). The ellipticity of M87 is shown by a dashed black line, with its error range shown in the shaded gray region. The median τ for each case is shown in the legend.