AB ColorChecker

A Flame Python script that colour matches two cameras using a Macbeth ColorChecker chart. Click 24 patches on Camera A (reference) and Camera B (source), then export a corrected EXR or 3D LUT. Works in ACEScg scene-linear.

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Features

• Standard Camera mode — pure 3x3 colour matrix correction, preserves full dynamic range and clean shadows
• HDR / 360 mode — Thin-Plate Spline RBF correction for wide-gamut cameras with negative channel values
• Export options — corrected EXR, 3D LUT (.cube), or both
• Image sequence support — process a full sequence in one go, output named <name>_matched.####.exr, auto-imports into Flame Batch
• Session save/recall — save A and B patch data by name, reload later to apply the same correction to new footage without re-clicking
• HDR session recall — load a saved HDR session and apply directly to a new B clip without re-clicking patches
• OpenImageIO support — uses oiio if available (standard on Linux VFX systems), falls back to OpenCV automatically

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Requirements

• Autodesk Flame 2026+
• Python packages: numpy and opencv-python (or OpenImageIO)

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Installation

Mac / Linux (recommended)

cd ab_colorchecker
bash install.sh

The install script finds your Flame Python automatically and installs any missing packages.

Manual installation

Copy the ab_colorchecker/ folder to:

/opt/Autodesk/shared/python/

So the path is:

/opt/Autodesk/shared/python/ab_colorchecker/__init__.py

Then install required packages:

/opt/Autodesk/python/*/bin/python3 -m pip install numpy opencv-python --break-system-packages

To find your exact Python path, run in Flame's Python console:

import sys; print(sys.executable)

First launch auto-install

If packages are missing on first launch, the script will attempt to install them automatically and prompt you to restart Flame.

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Studio / IT Installation

For air-gapped systems or environments where auto-install is not permitted, create a file called ab_colorchecker_paths.py in the same folder as __init__.py. Use it to point the script at your existing library installations:

import sys
sys.path.insert(0, '/opt/vfx/python/lib/python3.10/site-packages')

See ab_colorchecker_paths.py for examples. The script loads this file automatically if present — no changes to the main script needed.

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Usage

1. Right-click in Flame Batch or Media Panel → AB ColorChecker → Match Cameras...
2. Choose Standard Camera or HDR / 360
3. Load a Camera A frame and click all 24 patches in order (1→24)
4. Load a Camera B frame and click all 24 patches in order (1→24)
5. Click Apply Correction
6. Choose export: Single Image, Image Sequence, and/or 3D LUT

Session Save / Recall

• After clicking patches, enter a name and click Save Session to store the patch data
• Next time, click Load Session to restore the A side — just load a new B frame and click its 24 patches
• For HDR sessions, loading offers to apply directly to a new B clip without re-clicking

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Colour Space

Designed for ACEScg scene-linear footage. Both Camera A and Camera B frames should be in ACEScg before processing.

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Notes

• Standard mode uses a pure 3x3 matrix — zero always maps to zero, no shadow crushing, full dynamic range preserved
• HDR mode uses an RBF which gives better colour accuracy for wide-gamut cameras but requires EXR output (no LUT for HDR)
• The 3D LUT option is Standard mode only — the matrix is linear so the LUT closely matches the EXR output
• Sessions are saved as .json files and can be shared between machines

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Version

Current version: v3.9.2

See script docstring for full changelog.

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Licence

MIT — free to use, modify, and distribute.