Hmm, would this work for NNEDI3 still-image support, if AVISynth support is added:
http://avisynth.nl/index.php/Nnedi3ocl#Filters
I also found one Japanese Manga Viewer called "MangaMeeya" which supports AVISynth plugins for most of its features (google something like "comic+viewer+avisynth" and it's the only one that comes up), going to try and give it a shot myself (if interested, try tails's lasted translated version where he says he fixed Avisynth support).