Thanks for all the feedback!
You all refering to warmer grading of the DVD and Laserdisc releases got me thinking, so I checked out the 3D blu-ray again and I think you’re right, Titanic is meant to be warmer and have more of that sunset feel to it in daylight shots. I have adjusted the grading settings accordingly and will be releasing a Version 2 of the Titanic IMAX release very soon.
EDIT: V2 Screencaps removed because settings have been updated.