Example for the “Coffee Stain” filter
This filter adds realistic looking coffee stains to the image.
Every stain is created in a layer of its own. The stain layers are
randomly moved to let the stains spread out (at the end you may see the
boundary of the moved top layer). So after applying the filter you can
easily edit (e.g., move, scale, remove) the coffee stains, or create
additional stains using the filter again.