What is the actual visual characteristics of a black hole? Is there a safe distance in which a black hole can be observed with the human eye? What is a safe distance?

I have seen many computer simulated and artist renditions, and I am not sure if they depicted the true colors and shape of BH. 

Below I have a few of examples of what may a BH may look like rendered.


How light from the accretion disk maybe refracted by gravitational lensing.
http://www.physics.utah.edu/~bromley/blackhole/index.html



https://www.bbc.com/news/science-environment-38937141


https://www.nasa.gov/connect/chat/black_hole_chat.html

Should these models be mixed to make a more complete rendition of a BH?
This simulation (video link) has been made to show what a black hole might look like seen from different angles.
From APOD :

If the black hole was surrounded by a swirling disk of glowing and accreting gas, then the great gravity of the black hole would deflect light emitted by the disk to make it look very unusual. [...]  Surrounding the central black hole is a thin circular image of the orbiting disk that marks the position of the photon sphere -- inside of which lies the black hole's event horizon. Toward the left, parts of the large main image of the disk appear brighter as they move toward you.