IIRC it was a mix of a color-balanced GOUT, Puggo Strikes Back (16mm print), and Harmy’s eyeballs. I believe there was an incomplete 35mm source from Poita toward the end of this that may have also helped.
For example, while I think color-balanced GOUT was the major reference, there were a few instances where the GOUT diverged widely from PSB and other theatrical prints (the warm orange glow sometimes seen in the Cloud City halls was a cool blue in the GOUT). In those cases, PSB/prints were the reference. I believe the prints were similarly used to “settle” the issue of bluish ice on Hoth, not that people don’t still complain about it.
Thank you for the information. I’m currently working on a TN1 ESB Grindhouse restoration as my medium for learning film restoration. I’m using Dr. Dre’s Color Correction tool to make LUTs for every scene so I thought it’d be nice to know where the colors came from.