The DeFish filter on AviSynth is pretty good. There's a discussion on it on the Doom9 forum, perhaps the maths can be repurposed from there.
https://forum.doom9.org/showthread.php?t=152860
Or - could Reaper be made able to import / display / run AviSynth input? That could open a world of possibilities, albeit AviSynth itself is a bit "codey" to work with.