AM OCIO Colorspace

If you've ever handed a ComfyUI PNG to a compositor and watched them sigh, this node is the fix. AM OCIO Colorspace applies a real OpenColorIO 2.x transform between any two colorspaces in your active config - the same machinery Nuke, Katana, and every serious VFX pipeline use. It's how you get from "8-bit sRGB-ish tensor in a 0-1 range" to "scene-linear float that a comp can actually work with," and back.

It's part of comfyui-am-vfx-tools ("AM VFX Tools/Color" category), Adrian Meyer's 13-node VFX toolkit. The KB's take on this corner of the ecosystem is blunt and correct: OCIO in r/StableDiffusion is nearly invisible - the people who need it are compositors, not prompters - but the moment AI output has to survive as an element in a color-managed shot next to real footage, you need all of it, because one un-managed decode poisons the comp.

How it works

You pick two colorspaces from a dropdown of 56 choices - everything from Display/sRGB - Display and Display/Gamma 2.2 Rec.709 - Display through ACES/ACES2065-1, ACES/ACEScc, Rec.2100-HLG, and PQ. The node converts input_colorspace → working_colorspace through OpenColorIO's ColorProcessor. The list isn't hardcoded; it's generated from whichever OCIO config is active.

The config hierarchy is the same one the whole pack uses:

1. $OCIO environment variable, if set and resolvable
2. OCIO 2.5+ built-in Studio config (ACES)
3. OCIO 2.5+ built-in CG config
4. An identity stub so the nodes still load with no config at all

That means it works out of the box on any ComfyUI install with opencolorio>=2.5.0 - you don't need to source a studio config to get going, and you can point OCIO=/path/to/your.ocio to bring in your shop's real one.

When you reach for it

Three cases, honestly:

• Getting generated output into a comp - sRGB → ACES/ACES2065-1 before writing an EXR.
• Feeding a model with a colorspace assumption - many video models and samplers are trained on log or linear data; this is how you hand them the right thing.
• Just checking your work - convert a linear plate to sRGB to see what a viewer will actually see.

The two inputs are input_colorspace and working_colorspace, plus optional image and video (the video path is lazy per-frame). Outputs: image and video. Alpha passes through untouched either way.

Installing it

cd ComfyUI/custom_nodes
git clone https://github.com/am-pipeline-prod/comfyui-am-vfx-tools.git
cd comfyui-am-vfx-tools
pip install -r requirements.txt

Restart ComfyUI, or search comfyui-am-vfx-tools in ComfyUI Manager. The opencolorio>=2.5.0 dependency - the floor for the built-in Studio/CG configs - comes from that pip line, so don't skip it.

Where people get burned

The dropdown choices depend on the active config, so if your options look different from a tutorial's, you're on a different config - that's expected, not broken. And the classic mistake: applying a display transform and then grading in that display space. The pack's own nodes (AM Grade, AM Color Correct) assume scene-linear with a 0.18 pivot, so the sane chain is: read in → transform to linear working space → grade → transform to display → write. If your grades feel wrong, check which space the OCIO node put you in before you blame the grade.