Script-Fu -> High End Sharpen
This is a Python script that sharpens the upper-end (highlights) of an image. This generally looks better than an overall sharpen. The strength is adjustable and there is a choice of whether to flatten the image when complete -- but the scriptsmost noticable feature is that it has a PREVIEW option.
Rather that just run the script you can choose PREVIEW, and subsequently, UNDO PREVIEW, and the original image is untouched, and you can therefore play around with differing strengths of sharpening quickly and easily.
As you can see, the plug does not have its own preview window -- it overlays the image you are working on with the preview. The UNDO button is the real feature. It means you can test one setting after another without re-opening the plugin and starting over.
On Linux systems this file belongs in
...and you have to set it to be executable.
High End Sharpen with Preview - BEFORE
As you can see above, if you choose PREVIEW, you can then later choose UNDO PREVIEW and play around with the sharpen strength some more.
The functionality is SOMEWHAT clunky, and more complicated scripts with lots of parameters would be a real hassle to code. I made this script in 2007 and was hoping the Python scripting interface for GIMP would soon improve, but now (January 2010) I don't see many improvements. Perhaps there is some development being done I don't know about? I hope.
Because I REALLY like Python (especially compared to GIMP's Tiny-Fu, which I don't want to bad-mouth but OMG . . . ) If Python ever gained full implimentation (access to all GIMP routines) as well as a built-in preview function, I guarantee there would be an EXPLOSION of excellent new plugins for the GIMP.
If anyone knows of any developments along these lines -- please email me about such info.