"aura" is a desktop (X root window) background setter. It picks images randomly from specified paths, skipping those that are too small or have inappropriate aspect ratios, and rescales them by cropping solid margins, resizing with cubic interpolation and then the liquid rescale algorithm to fit the desktop with as little quality loss as possible. Images are labelled in the corner using embedded tags. It can changes images on a timed basis or when triggered by SIGHUP or the CLI, and tracks previous and blacklisted images.
Oboinus is X11 background previewer and setter. In normal working mode, Oboinus provides an interface that helps you to choose a picture to be set as the background. When the --restore option is passed, it sets the background that it has a configuration for and exits immediately (for use in .xinitrc/.xsession or your WM startup files).