s usual this is a Plugin for the GIMP, more exactly a version compiled for Windows (Xp or Vista.. )
Plugin was created by Marcor, this version ,the last available at this moment was compiled by Francois Collard
As you may guess from the name is for sharpen.
How to install and use, is explained inside in a included html file
For version of other OS, source code , and contact the developer please refer to[link]