  The Event Horizon Telescope Consortium is on the verge to provide the first
telescopic image of massive black holes SgrA* and M87* surrounded by accretion
disks, at a resolution scale comparable to the size of their event horizons.
Well before this remarkable achievement made possible by VLBI radio astronomy,
many researchers used the computer to reconstruct how a black hole surrounded
by luminous material would look from close-up views. The images must experience
extraordinary optical deformations due to the deflection of light rays produced
by the strong curvature of the space-time in the vicinity. General relativity
allows the calculation of such effects, both on a surrounding accretion disk
and on the background star field. This article is an exhaustive and illustrated
review of the numerical work on black hole imaging done during the first thirty
years of its history.
