Here are the optionnal deps which you can choose to install or not:

- file: for determining file types
- The python module chardet, in case of encoding detection problems
- "sudo" to use the "run as root"-feature
- w3m for previewing images in "true color".

And, for enhanced file previews (with "scope.sh"):

- img2txt (from caca-utils) for previewing images in ASCII-art
- highlight for syntax highlighting of code
- atool for previews of archives
- lynx, w3m or elinks for previews of html pages
- pdftotext for pdf previews
- transmission-show for viewing bit-torrent information
- mediainfo or exiftool for viewing information about media files

Note: previewing images in "true color" is disabled by default. To enable it,
first make sure you have w3m installed, then check that your terminal supports it.
It was successfully tested with urxvt and xterm, while it did not work with
gnome-terminal and st. Currently it does not work with tmux but with screen.
Finally, add this line to your ~/.config/ranger/rc.conf and restart ranger:

set preview_images true

Note: to use custom file previews, you need ranger 1.3.1 or later, and a script
that creates previews. Use the default script by typing:

ranger --copy-config=scope