It uses [ratatui-image][1] to render the images in the appropiate graphics protocol (sixel, kitty, or iterm2), if the terminal supports it.
Check out the gif in the README.md (e.g. on the github link) to get a better idea on what it actually does and looks like.
There is a setup step the first time you run mdfried, where a font must be picked (ideally the same font as the terminal). The first matching font for the prompt is previewed, you can force to run it again with `--setup`.
There are still a lot of missing features (and probably bugs), as I just published/released this. If your terminal supports any graphics protocol, and you're curious, please try it out! Feedback is welcome.