Those scans are definitely not from original exhibition prints; in the late 90s Lucasfilm distributed some limited edition film cells through the Star Wars Fan Club IIRC.

Here is a video about them: https://www.youtube.com/watch?v=bdfPhRXn_pU

On the back there’s some info “…hand cut from a master print taken from the original internegative…”. While I doubt the original 65mm internegatives for SW and TESB would have retained this much colour, the scans don’t appear modified. It seems that Lucasfilm does (or did who knows) have the originals on low-fade film stock. Oddly the cells for SW seem to resemble the Technicolor prints as they have similar colour shifts which leads me to suspect that a Tech print was involved at some point in the process.