Restoring Old Movies

[toef]

I'm sure this has been brought up before, but my lackluster searching skills weren't able to turn up any results.

I like a lot of classic movies, and I'm glad some of them are making their way onto BD, but this made me wonder what the process is like.

Can someone explain how lengthy a process it is to restore an old movie for BD? I know it's mostly (or completely) done by computers, but how long would a regular 2 hour movie take? If it's been brought up before, and if there is a good thread about this, can someone post the link to it.

Also, I kind of understand the difference between 2k and 4k, but how prevalent is 4k, and how does that factor into restoring movies for BD? Does 4k make a difference for non-gigantic screens?

Thanks.