Generate Lut

Generate LUT

Overview

Create practical .cube 3D LUTs with deterministic scripts, preview them on images or generated test charts, and validate the generated files before delivery. Support both creative display-referred looks and technical color transforms.

Workflow

1. Classify the request as creative look, technical transform, OCIO pipeline bake, preview/application, or validation.
2. For creative looks, use scripts/generate_cube_lut.py and default to LUT_3D_SIZE 33, strength 0.65, and .cube output unless the user asks otherwise.
3. For built-in technical transforms, use scripts/generate_technical_lut.py after confirming source/target primaries and transfer functions.
4. For show pipelines, camera transforms beyond the built-ins, ACES config workflows, or facility-managed color, use scripts/ocio_generate_lut.py with a user-supplied OCIO config.
5. For previews, use the user's sample image when provided; otherwise run scripts/create_test_assets.py if needed, then use assets/neutral-ramp.png and assets/color-checker.png.
6. Always run scripts/validate_lut.py on generated or edited .cube files before handing them over.
7. Deliver the .cube file, at least one preview image when possible, and a short note about intended use, source/target assumptions, and limits.

Script Guide

Generate a creative LUT:

python scripts/generate_cube_lut.py --look cinematic-teal-orange --strength 0.65 --size 33 --output output.cube

Generate a technical LUT with built-in color science:

python scripts/generate_technical_lut.py --source-space panasonic-v-gamut --source-transfer panasonic-vlog --target-space rec709 --target-transfer rec709 --tone-map luminance-reinhard --size 33 --output vlog-to-rec709.cube

Bake a LUT through OpenColorIO when a config is supplied:

python scripts/ocio_generate_lut.py --config config.ocio --source "Input - Panasonic V-Log" --target "Rec.709 Display" --size 33 --output ocio-baked.cube

Inspect available built-in and optional capabilities:

python scripts/color_science_status.py

Apply a LUT preview:

python scripts/apply_lut_preview.py --input sample.png --lut output.cube --output preview.png --mode comparison

Create fallback preview charts:

python scripts/create_test_assets.py --output-dir assets

Validate a LUT:

python scripts/validate_lut.py output.cube

Use --look neutral for test identity LUTs. Use --look custom with numeric controls such as --contrast, --saturation, --warmth, --exposure, and --lift when the user describes a look that does not fit a preset.

References

Read references/lut-format.md when changing parser/writer behavior or explaining .cube compatibility.

Read references/looks.md when selecting or tuning a creative preset from natural-language style requests.

Read references/color-workflow.md when distinguishing creative looks from technical transforms or planning previews.

Read references/technical-color-science.md when generating technical conversion LUTs, choosing primaries/transfer functions, or deciding whether an OCIO config is required.

Guardrails

Do not present creative LUTs as mathematically accurate camera, scene-linear, ACES, ICC, or display transforms. For technical transforms, name the source RGB primaries, source transfer, target RGB primaries, target transfer, tone map, LUT size, and whether output was clipped.

Do not claim a built-in camera conversion is an official vendor LUT. For exact camera/vendor/show looks, ask for the official LUT or an OCIO config and bake through scripts/ocio_generate_lut.py.

Keep neutral grey reasonably stable unless the user explicitly asks for a tinted look. Warn when a strong style intentionally shifts greys, clips saturated colors, or may behave differently across editors.

Prefer .cube for broad compatibility. Avoid exporting many sizes unless the user needs them; 33x33x33 is a good default balance, 17 is light and coarse, and 65 is larger and smoother.