darktable preset inspired by CineStill400D

What the style changes

The style sets six darktable modules, with two instances of color balance rgb. It is an interpretation built from CineStill’s product page and published reviews, since CineStill publishes no datasheet or curve. What the film is and how reviewers describe it is on the CineStill 400D film page. All figures below come from renders made with darktable-cli 5.6.0 at 1000 px, measured in CIELab.

• A flat curve. The tone curve lifts the blacks, keeps middle gray and holds the highlights back. Contrast drops (Lsd 30.7 → 29.1 on photo 1014), the darkest 5 % of the frame rise from L 2.6 to 6.4 and the brightest 5 % come down from 87.9 to 86.6. It is close to the Kodak Vision3 250D style’s curve, without copying its color.
• Pastel color. Sky chroma falls from 27.5 to 23.3 (−15 %) and sea chroma from 22.2 to 17.4 (−22 %), with hue almost unchanged. This is what sets it apart from the Vision3 250D style, which deepens blues.
• Warm skin. Skin chroma rises from 16.4 to 17.9 and its hue from 44.2° to 46.3°. A pink T-shirt keeps its chroma (33.7 → 33.2) but its hue moves from 358.8° to 5.2°, toward orange, because of the warm midtones.
• Shadows. The shadow on the ground goes from b* −3.5 to −1.0 and its a* from 1.9 to 1.1: the purple-blue cast of the base rendering disappears. The faint green is barely measurable. A white wall turns slightly cream (b* −0.8 → +1.2).
• Discreet halation. A second color balance rgb instance, named “halation”, adds red-orange light in and around the brightest areas through a parametric mask on input luminance. It is weaker than in the CineStill 800T style (offset 0.025 against 0.04). Gravel in the sun goes from a* 1.9 to 3.1 only.
• Very fine grain, with the same values as the Vision3 250D style, the only fine-grain reference available.

The mask and blur of the halation are the same as in the CineStill 800T style.

What it leaves alone

• Your base development. The style contains no exposure, no sigmoid or filmic, no white balance and no LUT. Those settings stay as you made them.
• Your color balance rgb. The style’s two instances are named “film” and “halation”: they are added next to yours, which stays untouched.
• But not your rgb primaries, color equalizer, tone curve or grain. When you apply a style from the lighttable or the darkroom, each of its modules replaces the instance of the same module with the same name, if the photo has one. These four modules carry no instance name, so they replace any settings you had already made in them. Your earlier settings remain in the history.
• Your pipeline order. The style file carries no module order list.

Exporting with a style, or rendering with darktable-cli, adds every module as a separate instance; our measurements were made that way. The details are in Install and apply darktable styles.

Limits

• Unknown base. Nothing confirms that 400D is Vision3 250D, and there is no manufacturer curve. Contrast, color and grain come from reviews, which disagree on the cast (amber, cool or green) and on the useful range.
• Shadow tint. The green tint of the shadows is measured as weak; it depends heavily on the scan.
• The scanner decides. A scan depends on the lab and the scanner. The white balance stays that of your photo.
• Halation is approximate and very discreet in daylight. The test photos have no point light sources at night, its main use, so it is not validated there. The mask depends on luminance, not on the energy of the source.
• Grain is almost invisible at 1000 px and visible only on the 2560 px examples.
• No reading of the “cool” daylight described by one reviewer: it contradicts the other sources.

Tips

• For night scenes, check the halation on your own frames: it was not tested on point lights.
• Apply it early if you plan to fine-tune the tone curve, rgb primaries, color equalizer or grain: the style would replace those settings if you made them before.
• Installation: see Install and apply darktable styles.