It seems like the prequels were sourced from the BluRay master but altered a bit from there, and the originals remastered from what the 2004 masters were sourced from but redone from there. 1997 changed are once again carried over, with anything subsequent being redone. A. couple of 2004 fixes seem to have been accidentally omitted, a few more have been done, and the previous 2004/2011 changes have been recreated (some more successfully than others). The originals have a far better color grade but have been processed to a greater degree that may not be desirable.