Feh is an advanced image viewer that uses imlib2.  Here is a summary of
features:
    * Simple image viewing.
    * Multiple image viewing (slideshow).
    * Multiple image viewing in multiwindows.
    * Image viewing in fullscreen.
    * Image list mode.
    * Loadable/unloadable listing.
    * Recursive file opening.
    * Sorting of the filelist
    * Saving/loading filelists
    * Loading images via http.
    * Reloading after delay.
    * Montage creation.
    * Collage creation.
    * Index print creation.
    * Thumbnail browser.

For viewing images, feh has the following features:
    * Progressive loading.
    * Dynamic zooming.
    * Panning.
    * Key or mouse control.
    * Context menus.