ww12345 said:

For what it's worth, Spaced Ranger, I think luminance stabilizing has to be done on a shot by shot basis. Iirc, that's what Antcufaalb said when we were working on some other 16mm projects. Maybe he'll pop in here and give us some more info...

This is true.

The easiest way to do it is to lock the brightness+contrast of a shot to that of its first frame.

(Now, this might screw up a shot of–for instance–a flickering lightbulb, but that's a different story...)

A certain program that ends in "clean" does this rather well.