As always I prefer to develop an algorithm to do my corrections for me, since unlike people algorithms are always objective and unbiased by personal taste. So I’ve developed an algorithm, that automatically corrects the 70 mm frames (or any other frames). The algorithm requies no other input, but the uncorrected frame, and automatically estimates the correct colors. Here are my results for the frames darth lucas posted:
The black levels are a bit off, but I’m pretty impressed how close this came to my manual adjustments.