Oh, I see.
...there are improvements in the image quality of the Prequel films on Blu-ray simply related to the improved "state of the art" of mastering from digital source material... It's accurate to say that these are probably built from the same negative scans that were done for the 2004 DVD release, at whatever resolution those were produced. (Note that I'm working to determine the exact resolution of the original digital masters of all the films...)
I don't entirely understand the whole process. My point was just that it's not the DVD file burned onto a Blu-ray disc, which is what some people appear to think.
Would the norm in 1997 or 98 have been to shoot at much higher than 1080p? I mean, I can look at a TV and know if it's HD or not (or if it's component cable or HDMI). But can you really see a difference between 1080p and 2k or 4k?