Hello,
I’m presenting a CTL script port for ART of the “3D Colorimetric Film” (3DCF)" module I developed in my experimental Libre DT-Lab branch of darktable.
The port
The goal was to reproduce the module’s behaviour in ART as faithfully as possible. The heart of the script follows the module’s dt_st_pipeline_eval() function 1:1:
- Rec.2020 (D50-adapted) → D50 XYZ
- ACES 2.0 SSTS tone mapping on luminance Y only
- BT.1886 + contrast S-curve (parametric toe/shoulder)
- Mid-tone gamma adjustment
- Chromaticity ratio scaling: x = ratio · Y
- Spectral gamut: film-like chromaticity roll-off in CIE xy
- XYZ → output RGB via the output matrix
- Abney hue rotation + highlight desaturation
- Vibrance (high-saturation-protected saturation)
- Chromatic contrast (luminance-adaptive mid-tone saturation boost)
- Gamut compression safety net + optional output gamut protection
- Color look blend (11 3×3 matrices)
The script works on linear values in ART’s Rec.2020 working space (1.0 = 100 nits), which matches ART’s CTL contract exactly. It’s evaluated as a 64³ LUT sampled in PQ space (@ART-lut: 64), like the other ART scripts.
What couldn’t be ported: the module’s “highlight detail recovery” (guided filter), which isn’t translatable to CTL. It’s simply omitted.
Here’s a screenshot with minimal processing, 3DCF + local contrast. Please keep in mind this is just a quick, minimalist example to illustrate the effect, not a finished edit, and it’s not meant to be a “one-click magic” solution. Not being an ART specialist, but I noticed it’s better to disable the tone curve.
Installation
- Download
3dcf.ctl. - Copy it into the
ctlscriptsfolder of the ART config folder:
- Linux:
$HOME/.config/ART/ctlscripts - Windows:
%LOCALAPPDATA%\ART\ctlscripts
- Restart ART.
- The script appears as an additional mode in the Color/Tone Correction tool (or Film Simulation), under the name “3D Colorimetric Film (3DCF)”.
All feedback and suggestions are welcome!
Greetings from the Luberon, 
Christian
