Adaptative ray-tracing polar grid with point densities adjusted for visual purposes. The real resolution values used in the simulated images are: angular resolution res^ψ = 3.6° (violet), n = 0 radial resolution res^{b,  n = 0} = 0.05 μas (orange) outside the inner shadow (brown), n = 1 radial resolution res^{b,  n = 1} = 0.005 μas (teal) in its lensing band (light blue). The star symbols represent the computed points of the apparent horizon and of the edges of the n = 1 lensing band before interpolation. The inner 30 μas of a mean-profile sample images are also shown.