OCIO CDL Transform Node

OCIO CDL Transform is part of Fusion's Open Color IO system. It applies grades in the ASC CDL format (American Society of Cinematographers - Color Decision List), an industry standard used to pass a primary grade between on-set, dailies, post and DI.

Main advantage: a CDL is a lightweight text file (10 values per shot) that is easy to share and reads back identically in any compatible software (Resolve, Baselight, Nuke, Flame...).

• Effects Library: Tools > Color > OCIO CDL Transform
• Quick add: right-click in the Node Editor → Add Tool > Color > OCIO CDL Transform

CDL is an exchange format created by the ASC to standardize a minimal primary grade that can be applied anywhere. It holds exactly 10 values:

• Slope (×3) - one per RGB channel, the equivalent of a Gain.
• Offset (×3) - one per RGB channel, the equivalent of a Lift/Brightness.
• Power (×3) - one per RGB channel, the equivalent of a Gamma.
• Saturation (×1) - global.

The formula applied per channel:

out = (in × Slope + Offset)^Power
then global desaturation

It is deliberately minimal - no color wheel, no tonal ranges, no hue curve. The idea: a grade you can exchange safely between software without any interpretation.

• Input (orange) - required. The 2D image to grade.
• Effect Mask (blue) - optional. Limits the grade to an area.

Typically placed after a Gamut that has linearized the shot from log/Rec.709.

MediaIn → Gamut (Linear) → OCIO CDL Transform → Gamut (output Rec.709) → Saver

Operation Mode

• File - loads an external CDL file (.cdl, .ccc, .cc). Typical use: receive a grade from the colorist and apply it.
• Controls - manual adjustments with sliders, with an export option. To create a grade or change an existing one.

Direction

• Forward - applies the CDL normally.
• Reverse - tries to undo a CDL (with mathematical limitations; Power in particular is not always cleanly invertible).

Slope R / G / B (default: 1.0)

Per-channel multiplier. > 1.0 = brighten, < 1.0 = darken. A different Slope on R/G/B tints the image.

Offset R / G / B (default: 0.0)

Added per channel. The equivalent of Brightness. > 0 = brighter, < 0 = darker. Different per channel = a uniform tint.

Power R / G / B (default: 1.0)

Per-channel exponent. The equivalent of Gamma. > 1 = darker midtones, < 1 = brighter midtones.

Saturation (default: 1.0)

Global saturation (not per channel). 0 = B&W, 1 = unchanged, 1.5 = boosted saturation.

Export File

Saves the current values as a standard .cdl file. Transferable to other software / studios.

For a colorist used to other tools:

Slope ≈ Gain

Maximum impact on the highlights. The equivalent of an exposure gain.

Offset ≈ Lift

Shifts the whole histogram by a constant value. Maximum impact on the shadows.

Power ≈ Gamma

Adjusts the midtones without affecting the extremes. Power < 1 = brighter midtones, Power > 1 = darker (watch out for the inversion compared with the classic gamma convention in some software).

Together, S/O/P cover the tonal ranges (highlights/shadows/midtones) much like the Lift/Gamma/Gain of a Color Corrector - but codified as a shareable standard.

Supported formats:

• .cdl - the basic ASC CDL XML format.
• .ccc - Color Correction Collection (several CDLs in one file).
• .cc - an individual Color Correction.

Typical workflow: the on-set or dailies colorist produces one CDL file per shot. In post, you load this CDL into OCIO CDL Transform as a starting point → VFX starts from the same look as the final colorist.

• Receiving an on-set grade in VFX post - the DIT delivers one .cdl per shot. In comp, load this CDL to work with the right look from the start.
• Matching a reference look - the colorist sends their reference CDL, and compositing applies it to preview the final render.
• Standardized studio pipeline - CDLs travel through an OCIO config shared by every department (grading, VFX, editorial, DIT).
• Dailies / look preview - apply a quick CDL to generate dailies with the intended look without running a real grade.
• A quick, exportable primary grade - a CDL is often enough for a primary. Exporting it as .cdl lets any other tool read it back identically.
• Archiving a look - 10 values in a text file = a look preserved forever, regardless of the software.

• Mind the working space - a CDL is defined for a specific color space (typically log or linear). Applying a log CDL to a Rec.709 image gives a different result. Check the expected space with the colorist.
• Slope = Gain in Fusion - no trap if you come from Color Corrector, but keep in mind that S/O/P are another name for Gain/Lift/Gamma.
• Reverse is not perfect - Power in particular is not 100% mathematically invertible. To get back to the original, disable the node instead.
• Export a CDL to share with the colorist - if you built a VFX look in an OCIO CDL Transform node, export it so the colorist can see it in their system.
• Ideally place it in linear space - S/O/P works better mathematically in linear. Sandwich it with Gamut as usual.
• For more advanced grading (fine tonal ranges, secondaries), use OCIO CDL as a base, then refine with a Color Corrector or Hue Curves downstream.
• An OCIO config is required - this node relies on an active OCIO config. Without a config (a freelance project with no setup), prefer Color Corrector or Gamut.