LED Wall Color Management in UE5

Context

An LED volume is a display driving a light source - not a grading monitor. The image on the wall is real-time pixels captured through a camera with its own response curve, IDT, and show pipeline. Until that full chain is verified, wall-to-grade mismatches are expected. This note covers how to set up OCIO correctly in UE5 and what to check when the wall doesn't match.

Checklist

Run these during prep, tech scout, or day-zero before any creative work starts.

• ACES version and OCIO config are confirmed against the show pipeline.
• Wall target display space (typically P3-D65) agreed with the stage vendor.
• Reference monitor uses the same ODT as dailies.
• Camera IDT matches the exact sensor mode and firmware in use.
• Show LUT is applied once - confirm where, and rule out a second application downstream.
• Chart and skin tone test captured and signed off with the DP.

ACES/OCIO Setup (Practical Order)

1) Agree the ACES version and OCIO config with your DIT and post pipeline before anything else. 2) Set the wall target display space - P3-D65 is standard for most modern LED stages; confirm with the vendor. 3) Build a clean chain: camera IDT -> ACEScg working space -> look transforms -> display ODT. 4) Validate the ODT on a calibrated reference monitor before the wall is involved. 5) Load the same OCIO config into UE5's nDisplay configuration and version-lock it - wall, dailies, and DI need to reference the same file.

Calibration Gotchas That Break Color

When the wall doesn't match, it's almost always one of these.

• Wall calibrated to the wrong target space or white point.
• Panel drift - re-profile after swaps or extended heavy use.
• OCIO config version mismatch between UE5 and the dailies/preview tools.
• Show LUT applied twice - once in Unreal, once at video village.
• Camera IDT swapped out by a vendor LUT without being flagged.
• LED processor adding an undocumented transform via its own calibration layer.

Why The Wall Never Looks Like The Grade (Until It Does)

Early in prep you're comparing a live, partial pipeline against a final-grade reference. The mismatch is expected - it means the chain isn't verified yet, not that something is broken. When the camera pipeline is locked, the wall is calibrated to the correct display target, and the OCIO config is consistent across every tool in the room, the wall will match. That alignment is the goal of the verification process, not a happy accident.

On-Set Verification Loop

Shoot a chart, skin tone, and neutral gray in the volume and route the camera feed through the exact OCIO pipeline used for dailies. If it matches within tolerance, lock the chain and document every setting. If it doesn't, change one variable at a time and log each change - guessing in parallel wastes time and creates new unknowns.