Atlas Export ACEScg Plate 📤

AtlasExportPlateEXR solves a problem most ComfyUI users don't know they have: you cannot save a real scene-linear ACEScg EXR from the tensor path. ComfyUI's IMAGE tensors are display-referred and effectively 8-bit, so "save an EXR" through the normal tensor route gives you an sRGB-encoded file wearing a float costume - hand that to a Nuke comp and every blend and merge blows out, because gamma-encoded values got treated as linear light. This node never touches the tensor. It takes a file reference, converts it float-to-float through OpenColorIO, and writes a properly tagged ACEScg EXR that a DCC reads back correctly with zero out-of-band knowledge.

If you've ever fed AI output into a color-managed VFX pipeline and gotten weird, washed-out results, this is the node that fixes the root cause instead of the symptom. It's the file-based handoff the atlas-camera colour doctrine is built around.

How it works

You feed it a plate_ref - typically the scene-linear sidecar from AtlasLoadRAW, which is deliberately tagged Linear Rec.709 (sRGB) at the demosaic rather than falsely marked ACEScg. The node reads the file, converts it through OCIO (unpremultiply → convert → re-premultiply), and writes a new EXR tagged oiio:ColorSpace with the target space. The returned plate_ref now points at the converted file, so wiring it into the plate-attach node makes every DCC export reference the ACEScg plate.

output_colorspace defaults to ACEScg but accepts anything the built-in ACES config knows - ACEScct, ACES2065-1, and so on. bit_depth is half by default (the VFX plate standard, 16-bit float) or float for 32-bit.

The inputs

plate_ref is required. Then output_colorspace, output_dir, bit_depth, file_name, and project. Outputs: exr_path, the converted plate_ref, and a report.

Install and gotchas

This one has a real dependency: it needs the [oiio] extra (OpenImageIO-backed). From a clone:

cd <ComfyUI>/custom_nodes/atlas-camera
<ComfyUI-python> -m pip install -e ".[oiio]"

Then restart ComfyUI. It's the pack's own colour path using OpenImageIO's built-in ACES config - no $OCIO environment to configure, no third-party colour pack.

Gotchas worth knowing: a proxy or missing plate reference degrades soft (the report says so, the input ref passes through) because an export chain must never die on a preview-only plate. And if you wire a browser-preview-only ref in, it skips with a clear message - the node needs an actual on-disk file, which is the entire point. Also note this is a file-to-file converter, not a tensor node: the input is an ATLAS_PLATE_REF, not an IMAGE. Get the workflow right and you'll never hand an sRGB-in-EXR-disguise to a comp again.