Freeware Descriptions:
The word vignetting is used to indicate an unintended darkening of the image corners in a photographic image. It is a common problem due to the use of improper attachments to the camera lens. Vignetting Reducer is a simple tool for reducing vignetting in digital photos.
Here is complete features (taken from authors site):

File Size / OS:
- 434 KB / Windows 9x - ME - 2000 - NT - XP - 2003 - Vista
Download Vignetting Reducer 1.3: