File vignetting-demo.c demonstrates how to perform various types of "vignetting effect". It was developed on January 2009, during a computer vision class at University of Edinburgh, Informatics Dept. It uses the OpenCV framework. More information is available at UoE pages: http://homepages.inf.ed.ac.uk/rbf/CVonline/LOCAL_COPIES/AV0809/laskaris.pdf
(Update) Local copy: https://github.com/laskasn/OpenCV/blob/master/laskaris.pdf
Created various algorithms to extract image features and perform a feasibility study on skin cancer identification. It was developed in 2008, for my thesis @ University of the Aegean, Information & Communicaiton Systems Engineering Dept. It used extensively the OpenCV framework.
More information is available at University of the Aegean pages (in Greek language): http://hellanicus.lib.aegean.gr/handle/11610/8921
Fulltext link (in Greek Language): http://hellanicus.lib.aegean.gr/bitstream/handle/11610/8921/file0.pdf?sequence=1&isAllowed=y