xterm and Konsole allow to display images in the terminal. To check it out, install w3m with the w3m-img patch (in Debian, the "w3m-img" package; in Arch Linux, the "w3m" and "imlib2" packages) and open a webpage that contains plain <img src="..." /> tags.
The rendering is really buggy. Images glitch away all the time, possibly until w3m issues a redraw event, but it kinda sorta works.
Some day, I'll have to dig into either the w3m source or the Konsole source and figure out which ANSI escapes are being used for that. (If someone has a link to a spec or sth, that'd be much appreciated.)
Example screenshot from Konsole: https://imgur.com/a/D98Kl (showing https://en.wikipedia.org/wiki/xterm)
The rendering is really buggy. Images glitch away all the time, possibly until w3m issues a redraw event, but it kinda sorta works.
Some day, I'll have to dig into either the w3m source or the Konsole source and figure out which ANSI escapes are being used for that. (If someone has a link to a spec or sth, that'd be much appreciated.)