Image of a 2D optically thick disk emitting blackbody radiation with an inclination of 85° and in the presence of the RWI. The first-order image (the distorted complete ring) clearly shows the spiral shape of the emitting region. The beaming effect makes the emission brighter on the approaching side of the disk (here, on the left of the image). The second-order image is the portion of ring at the bottom of the image. It is due to photon swirling around the black hole before reaching the observer. The third-order image is the thin ring of illuminated pixels at the center of the image, which is due to photons orbiting around the black hole very close to the event horizon before reaching the observer. This ring is the so-called black hole silhouette; it is truncated here due to optical thickness.