Samuelsujan's EXR Plate

Samuelsujan's EXR Plate — Linear EXR I/O for Nuke ↔ ComfyUI

Custom ComfyUI nodes plus a Nuke bridge for working with linear EXR plates in AI-assisted VFX pipelines — without breaking your colorspace.

Built by a compositor, for compositors. Generative models want sRGB in the 0–1 range; your plates live in scene-linear EXR. This pack handles the conversion both ways with pure, invertible transfer-function math, so what comes back into Nuke merges cleanly over your original plate.

Author: Gunupudi Samuel Sujan Deep (Samuelsujan) — Nuke Compositor LinkedIn: https://www.linkedin.com/in/gunupudi-samuel-sujandeep-a316bb225/

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What's included

ComfyUI nodes (category: EXR Plate)

Load EXR Plate (linear)

• Single EXR, #### / %04d sequences, or a bare folder of EXRs
• first_frame / last_frame range (0 = auto-detect all frames)
• VHS-style controls: fps, custom_width / custom_height (keep-aspect), frame_load_cap, skip_first_frames, select_every_nth
• Colorspace transforms: keep linear, linear ↔ sRGB, linear ↔ Rec.709
• Exposure in stops (applied in linear), HDR passthrough via clamp_output
• Live plate preview inside the node — updates the moment the path, colorspace, or exposure changes, with sequence playback (▶ button, loops at the fps you set) and a resolution / frame-count readout
• "choose exr sequence to upload" button for drag-free loading
• Outputs: image, alpha, frame_count, fps, and a VHS-compatible video_info

Save Plate (linear)

• Formats: EXR (half/float, ZIP compressed, keeps HDR values above 1), TIFF 16/8-bit, PNG 16/8-bit, JPG (integer formats clamp to 0-1)
• Inverse transforms (e.g. sRGB → linear) so results land back in linear for Nuke — no LUT guessing
• Optional resize on save, alpha re-embed from a MASK input

Path Builder (versioned)

• Browse button that walks the machine ComfyUI is running on — drive letters included, so D:/disk/city/... is two clicks, not a paste
• No show/shot/task fields: one browsed folder, an optional subpath, and a name. Nothing to wedge by pasting a full path into the wrong box
• Version resolves at execute time, not when you set the widget: auto_next takes the highest v### on disk + 1, auto_latest reads the current one, manual uses the widget verbatim. Queue twice and you get v004 then v005 — no silent overwrite
• version_style: folder → .../v003/plate.####.exr, or filename → .../plate_v003.####.exr
• Live readout on the node showing the exact path the next run will write
• Outputs path (wire into Save Plate or Load EXR Plate), folder, and version as an INT

Note: Save Plate always sets the extension from its own format dropdown, so the builder's ext matters for Load and for reading the path, not for what Save writes.

Linear → sRGB / sRGB → Linear

• Standalone converters for sandwiching a generative model mid-graph

Nuke bridge (nuke_comfy_bridge.py)

• F9 — Send Plate to Load EXR Plate: select a Read in Nuke, press F9, and the plate appears in the Load EXR Plate node on your open ComfyUI canvas — path and frame range filled, preview showing. Non-Read selections are baked to a temp linear EXR first (with confirmation).
• ComfyUI → Nuke push: enable send_to_nuke on Save Plate and the finished render appears in Nuke as a Read node the moment the graph completes (the bridge auto-starts a listener on port 8189 when Nuke loads).
• F10 — Run Workflow on Selected (full bridge): bakes the selected node to linear EXR, injects it into a ComfyUI workflow of your choice, submits it over the HTTP API, waits with a cancellable progress bar, and imports the result as a linear Read node next to your selection.
• Versioned output: F10's panel has a Versioned output checkbox (on by default). Job folders go to <out dir>/<node name>/v001/, v002/, ... using the same v### rule as the Path Builder node, instead of a timestamp nobody can read.
• Path Builder aware: if the workflow's Save path is wired from a Path Builder rather than typed in, the bridge points the builder at the job folder and lets it pick the version, then imports whatever actually landed — it doesn't overwrite the link and break the graph.

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Installation

1. ComfyUI nodes

Copy the comfyui-exr-plate folder into your ComfyUI custom nodes directory:

ComfyUI/custom_nodes/comfyui-exr-plate/
    __init__.py
    nodes.py
    path_builder.py
    pyproject.toml
    requirements.txt
    nuke_comfy_bridge.py          <- copy this one to ~/.nuke/
    menu_snippet.py               <- paste into ~/.nuke/menu.py
    passthrough_api_format.json
    versioned_save_api_format.json
    web/exr_plate.js
    web/exr_plate_pathbuilder.js

web/ has to stay a subfolder — WEB_DIRECTORY = "./web" in __init__.py is what makes ComfyUI serve the JS. Everything else sits flat.

If OpenCV isn't already in your ComfyUI Python environment:

pip install -r requirements.txt

Restart ComfyUI and hard-refresh the browser (Ctrl+Shift+R). The nodes appear under Add Node → EXR Plate.

2. Nuke bridge

1. Copy nuke_comfy_bridge.py to your .nuke folder (Windows: C:\Users\<you>\.nuke\, Linux/macOS: ~/.nuke/).
2. Add the contents of menu_snippet.py to your .nuke/menu.py (create menu.py if it doesn't exist).
3. Restart Nuke. A Samuelsujan menu appears with both commands.

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Quick start

1. Start ComfyUI and open it in your browser.
2. In Nuke, select the Read node of your EXR plate and press F9.
3. Switch to the browser — your plate is in the Load EXR Plate node. Press ▶ on the preview to loop the sequence.
4. Build your graph. Feeding a diffusion / video model? Set the loader's colorspace to linear → sRGB (or use the standalone converters), and set Save EXR Plate to sRGB → linear.
5. Read the saved sequence back in Nuke — it's linear, and merges straight over your plate.

Verifying the roundtrip

Run passthrough_api_format.json (Load → Save, nothing between, both set to "keep linear", clamp off) on any plate, then in Nuke Merge (minus) the result against the source and gain up. Black frame = lossless linear pipeline.

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Requirements

• ComfyUI (local install — custom nodes don't run on hosted Comfy Cloud)
• Python packages: opencv-python >= 4.6, numpy (torch ships with ComfyUI)
• Nuke 13+ for the bridge (any recent Python-3 Nuke)
• The full bridge (F10) needs workflows exported via Save (API Format) (enable dev mode in ComfyUI settings)

Troubleshooting

• Nodes don't appear — check the folder name has no extra nesting (custom_nodes/comfyui-exr-plate/nodes.py, not custom_nodes/comfyui-exr-plate/comfyui-exr-plate/nodes.py), then check the ComfyUI console for import errors (usually missing OpenCV).
• No preview — the preview needs the web/ folder in place and a browser hard-refresh after install.
• Browse dialog is empty / errors — the browse endpoint runs server-side, so it lists the filesystem of the machine ComfyUI is on. On a remote or hosted instance you'll see that machine's disks, not yours.
• Version doesn't bump — check version_mode isn't on manual, and that the existing versions actually match v### (the scan ignores rev2, version_2, etc.).
• F9 does nothing in the browser — ComfyUI must be running and the tab open; check the host at the top of nuke_comfy_bridge.py (default http://127.0.0.1:8188).
• Preview looks dark — that's your plate in true linear; switch the colorspace widget to linear → sRGB to view it display-referred.

License

MIT — see LICENSE. Use it on your shows, fork it, improve it.