I know 70mm has been around a long time, I just didn't know there was such a difference between traditional 70mm and IMAX 70mm. Like I said...I thought it was mainly aspect ratio.
from what I understand, it's really difficult to directly compare/infer between film and digital formats. I recall 6 MP being the first primary goal of digital cameras, because that was the supposed "resolution" of 35mm film---but even so, the digital standard then was just APSC (or whatever it's called) sized sensors and not the full-frame standard for film cameras. I think 6MP is actually ~3.5k or "fake" 4K?
Digital 4K film cameras, and only hyper expensive super professional models at that, were still a decade away from that 6MP milestone for DSLRs. I don't really know what all of this means, other than film media has a lot of life left in it and sensitivities (color reproduction and contrast) that it seems digital still can't quite "perfect." I also don't think it scales linearly, because it's not like film has pixels. It can only ever be an approximation, and I'm not sure how accurate it would be to try and draw a quantified comparison between color depth and all that.
Honestly, no original source should ever be digital (outside of real cost needs, I guess), because film stock allows for far much more processing as long as you maintain it (expensive, though). I mean, professional, archived material.
I recall one of the more hilarious blunders in that 6MP/mini DV (lol!) era where Dave Gilmour (maybe it wasn't him), wanted that show in Gadansk recorded in digital...which at the time was mini-DV format. So, kinda sorta DVD, at 640P or whatever that is. lol. It will only ever be that shitty now, with no hope of improving that turd.
And didn't Lucas do this with the shitty prequels, and they are all trapped at 1080P now? I could be wrong.