So back when the original DVDs were made in 1999-ish, they were scanned and stored at a resolution that didn't yet exist for the pubic, in anticipation of a yet-to-be developed HD medium?
Please take the time and look up "HDTV" at Wikipedia.org, by the mid-90's the arrival of public HDTV was already in the pipeline. For the anamorphic (16X9 enhanced) widescreen DVDs (introduced 1997) they didn't use pre-existing old masters but already made new transfers in HD to prepare for HD broadcast and downconvert the resolution to sell DVDs.
Many of these HD masters were used for HD broadcast but in many cases, once HD-DVD and Blu-ray disc arrived, the studios felt the original HD masters were no longer state-of-the-art and decided they needed new ones with better HD resolution.
I'm simply not sure whether TOS relied on these early HD masters or whether new ones were made. Even in the current HD resolution, I'd say there is about 10-20% original live action footage where original negatives apparently got lost (10-20% live footage seems to have been replaced with footage from low resolution film copies that equals the sharpness levels of the current TOS DVDs).
Sorry for strolling off-topic, I shall add an on-topic comment in a few minutes to put the thread back on track.