42041 provided a link to an early computerized postproduction article on another forum:http://www.swdfx.com/PDF/Dig_Cinema_Take2.pdf
Here's an O Brother, Where Art Thou before/after comparison from that article:
That image definitely reinforces the idea that Deakins wanted stronger yellows and greens. Here is that same scene from the DVD:
It will be interesting to see how close the Blu-ray comes to matching the image in that article. I suspect its going to be a lot closer.
Well, I can admit when I was wrong. All of the evidence surely does point toward the Blu-ray colors being closer to what Deakins wanted, even from the start. It looks like the DVD is the version with the inaccurate colors.