Hello, thanks for this but it's not working for me. I just dropped the two files under C:\Program Files\Paint.NET\FileTypes\
I can tell it's not working because the filesize is the same whether p.net starts with the two files or without. Also, when I run the files through jpegtran.exe they get smaller, so the optimization wasn't applied. (I'm opening random jpg files and using 'save as')
I checked with ProcessExplorer and under p.net's NET assemblies tab I see OptimizedJPEG.dll, so it is loaded. I'm using version 3.5.10 under win7 x64. Any ideas ?