Also, FWIW, transferring right off the OCN typically does not result in anything like accurate theatrical colors, so some sort of color grading does need to happen when creating a new HD master.
Sometimes they honestly try to do a good job, but don't (and for the life of me, I don't understand why) use any sort of color reference. You end up with Blu-rays that look quite good, but totally unlike the theatrical colors (example: Do the Right Thing).
Sometimes they go through the trouble of matching the color temperature of a projector bulb from the same era and end up looking totally unlike all previous home video releases, and people don't believe the colors are accurate even when they actually are.
And sometimes they go all revisionist. In many cases, it's because the color grading was done by people who grade things in teal and orange all day long, and they just go through the same process they always use, and somehow they manage to get someone to sign off on it.