GIMP Convolution Matrix
Author here (of the plugin, not the page).<p>This was my only tangible contribution to the Gimp, some twenty years ago. IIRC it was modelled after a similar feature in Paint Shop Pro, and it was easy enough an exercise for an aspiring programmer. Or so I thought: others have now spent much more time maintaining it than I spent writing it.<p>In hindsight it seems like a bizarre idea to have a feature whose GUI requires filling in 25 numbers. But perhaps it has use as an educational tool.<p>In development version of the Gimp, the entire plugin has effectively been rewritten. Good riddance!