To support the IMAX scenes, the studios could not work in full IMAX resolution, which is theoretically 18K; instead, the target resolution was approximately 8K, the maximum resolution for scanned film. Even that was difficult. “A single 8K frame requires 200 MB of data,” Franklin says.
A second big bottleneck, though, was in viewing the images. “Our biggest monitors are 2K,” Franklin says. “You can’t realistically buy a 5.6 x 3.6K monitor, and the highest-resolution digital projector is about 4K.” So the studio wrote a set of tools that extracted 2K tiles from the images for the artists to view, but for dailies, they sent files from their London-based studio to DKP 70mm, the IMAX-subsidiary post facility in Los Angeles, for recording onto film stock.
“It was a minimum of 10 days before we saw the shots back in the UK,” Franklin says. What’s more, to view the shots, they had to book time at London’s only IMAX theater. “And you can’t rock and roll on IMAX projectors,” he adds. “You have to rewind and go again, so we had only a couple chances to view the output.”
You kind of have to read this if you're at all interested in the visual tech behind the biggest movie of the year (all time?). See also Marrying IMAX and 35mm in The Dark Knight.