system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How are Blu-ray versions to old movies made?
gpt
Until *very* recently — like minutes ago, in the grand scheme of things — movies were shot on film. This produces a set of camera negatives. The negatives are printed, then the prints are edited, then once the edit is locked, the same edits are applied to the original camera negative. The cut negative is then printed repeatedly to make the release prints.

It's no problem to go back to the original cut camera negative (or a first-generation interpositive) and scan it to videotape in high definition, a process called "telecine." (From "television" and "cinema," obviously.)

In fact, it's become … well, not *commonplace,* but not unheard of, to scan the negative not to videotape, but rather to computer files at resolution significantly higher than videotape. From there you can do exactly the same kind of digital-intermediate post workflow you'd do if the film had been shot yesterday.