About the laserdisc ...
AntcuFaalb said:
How much vertical stretch is there? I'm able to register to the BD pretty well after vertically compressing the 278 active lines to 270.
I took my own advise and did a compare of the 16mm to the 2004 DVD (mostly-the-same as the 2010 Blu-ray). A TV-to-PC resize (720x480 to 640x480) for the 16mm and a TV-to-PC (720x480 to 640x480) & anamorphic (640x480 to 853x480 [*edit note: rounding 16:9 from 1.777... to 1.78 would produce 854x480, an even value better for digital video manipulation*]) resize for the DVD was transparently overlayed. It showed a similar vertical mis-proportion as AntcuFaalb discovered between the laserdisc and Blu-ray:
When a vertical squash was applied to the 16mm (done that way only to maintain the DVD framing), it then lined up with the DVD:
In reality, it is the 16mm (and the LucasFilm-unmolested laserdisc) that is the optically trusted source. The later DVD and Blu-ray are the ones requiring vertical stretch to properly line up with original photography of the 16mm and laserdisc. That is because THX 1138 was originally filmed in Techniscope, which uses a spherical-lens camera (no optical squashing, on which to blame loss of exact aspect-ratio, as could be with other widescreen techniques):
https://en.wikipedia.org/wiki/Techniscope
Interesting that the difference here is 8 lines and AntcuFaalb's difference is also 8 lines. Of course, this information doesn't affect the laserdisc preservation. It does show that GL revisionism altered THX 1138 in yet another way. :O
Pray he doesn't alter it any further ...