My gimp plugin for converting greyscale images into black and white. Useful for very quick and dirty diagrams for lecture notes.
Description at: https://jevonlongdell.github.io/photos/tramping/2013/03/03/Using-camera-as-scanner-for-text-and-lineart.html
As of 2024, it might need a bit of work to make work with latest version of Gimp.