althor1138 said:

I came up with this idea a couple of weeks ago ... (This denoiser samples the black bars for noise and uses this information to denoise the film area.)

Well done! I've always been enamored of temporal noise self-cancellation but never considered spacial noise (though out of useful picture area) for self-cancellation in the same fashion. Your idea is clever, to the point of genius.

I have used the MVDenoise() [from ver. 1.x, now superseded] and MVAnalyse() functions from Manao & Fizick's Avisynth filter MVTools http://avisynth.org.ru/mvtools/mvtools2.html to good cleaning effect (shown here with other corrections, so just ignore those parts):

Only one temporal frame, backward & forward, made for effective and unobtrusive de-noising of this 16mm frame (reducing multi-generation grain instead of electronic noise -- both "random"). However, experience has shown that one cannot use too many backward & forward frames without risking obvious noise crawl from repeated usage of those frames. (This may be a filter flaw, but it's hard to tell. So much of this filter does not have quantifiable feedback on exactly what is being done by user settings.)

Could you post a representative before/after full-sized frame .PNG?