Refocus is a plug-in for the Gimp (the GNU Image Manipulation Program). This plug-in attempts to "refocus" the image, using a technique called FIR Wiener filtering. The traditional technique for sharpening images is to use unsharp masking. Refocus generally produces better results than unsharp masking.
The plug-in comes with a preview that helps you select the best parameters.here.
The following images give you an impression of the effect of this plug-in.
The Wilber images at the top of this page show what the plug-in can do under optimal conditions. The image on the right is really the refocussed version of the image on the left.http://www.gtk.org). The most recent version of Refocus can be downloaded from its Sourceforge download page. http://refocus.sourceforge.net. The Sourceforge project home page is http://sourceforge.net/projects/refocus. here. firstname.lastname@example.org