486750.fig.004a
(a)
486750.fig.004b
(b)
Figure 4: Images of rings of light of (a) a Kerr and (b) a quasi-Kerr black hole at an inclination . Increasing values of the spin cause a displacement of the ring in the image plane, but the ring remains (nearly) circular for values of the spin  M (a). Nonzero values of the deviation parameter (b) lead to an asymmetric ring image [23].