TMK very little of its effects are strictly new: almost all are digitally re-composited, color-corrected and slightly enhanced high-resolution scans of the orig

TMK very little of its effects are strictly new: almost all are digitally re-composited, color-corrected and slightly enhanced high-resolution scans of the original film footage (which used physical models and optical effects), since they were still available. IIRC, planets - as seen from space - are a notable exception (and better for it). It was a major remastering process, with beautiful results. (Although major, remastering cost less (for the whole series) than a single episode of the (IMO) abomination called "Discovery".) Sadly, such an approach is impossible for the majority parts of the latter series (DS9, VOY) since their effects were mostly CGI, and rendered directly to standard definition video. Further more, many of the 3D models and scenes have been lost, so it would probably require a total effects re-do from scratch (on top of film stock scans), which is "a very costly proposition with questionable (financial) returns".