SlackBuilds/libraries/libsixel

This package provides encoder/decoder implementation for DEC SIXEL
graphics, and some converter programs.

SIXEL is one of image formats for printer and terminal imaging
introduced by Digital Equipment Corp. (DEC). Its data scheme is
represented as a terminal-friendly escape sequence. So if you want
to view a SIXEL image file, all you have to do is "cat" it to your
terminal.

mlterm is recommended for good SIXEL support.