darktable preset inspired by FujifilmNeopan 400

What the style changes

The style converts the photo to black and white the way Neopan 400 sees color, then adds its contrast, light sharpening and fine grain. What it is based on is detailed on the Fujifilm Neopan 400 film page. Renders were made at 1000 px with tools/validate.py and measured in CIELab, next to the Tri-X 400, HP5 Plus and Acros 100 II styles for comparison.

• Gray from the daylight spectrogram. A color calibration instance named “N&B” mixes the channels with weights integrated from the AF3-706E curve. Its blue weight (Z 0.366) is close to the Tri-X style (0.386) and far from Acros 100 II (0.238) and HP5 Plus (0.49), because the Neopan curve does not hold the blue back. The sky measures L 60.7 (base 55.3), the same as Tri-X (60.7) and lighter than Acros 100 II (58.6).
• Contrast. The whole-image contrast (Lsd) goes from 30.7 to 33.0 on one test photo and from 14.3 to 17.5 on another: between HP5 Plus (30.6, 15.8) and Tri-X (33.5, 18.0).
• Shadows and whites. The darkest 5 % of the frame drops from L 2.6 to 1.4 (Tri-X: 0.8, HP5 Plus: 1.9), so the shadows are more open than Tri-X but denser than HP5 Plus. The whites rise from 87.9 to 91.6, equal to Acros 100 II (91.6) and above Tri-X (90.6) and HP5 Plus (86.7).
• A truly neutral gray. Chroma falls from 8.6 to 0.0.

What it leaves alone

• Your base development. The style contains no exposure, no sigmoid or filmic and no LUT. Those settings stay as you made them.

• But it switches off your main color calibration. The style contains two color calibration instances:

  • a disabled one with no instance name, which replaces your main color calibration and switches it off. It is set to “as shot in camera” with CAT16, like darktable’s default, so you can switch it back on;
  • the “N&B” instance, which does the black-and-white conversion.

  Why: an active color calibration running after the conversion would tint the gray through its chromatic adaptation.

• It also replaces your tone curve, sharpen and grain. The style’s modules carry no instance name, so on the lighttable or in the darkroom they replace any settings you had already made in those modules (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 works differently: every module is added as a separate instance. The details are in Install and apply darktable styles.

Limits

• An interpretation, not a calibration. No film was scanned or measured to tune the style.
• Old datasheet, no granularity. AF3-706E dates from 1999 and gives no RMS or resolution. Grain and sharpness rest on reviews and are chosen values.
• Reading of the graph. The spectrogram was digitized column by column (about ±0.02 log). Sensitivity is counted as zero beyond 653 nm. The 5400 K light is modeled as a Planck spectrum: between 5000 and 5800 K, the Z weight moves from 0.386 to 0.349.
• Developer-dependent contrast. The style aims at a mean gradient of 0.54 (D-76, 7½ min). Pushing or another developer changes the look a lot (0.83 at 12 min).
• Low distinction from Tri-X. The spectral weights are close (0.3198, 0.3142, 0.3660 against 0.3149, 0.2994, 0.3857). The measured differences (more open shadows, higher whites, finer grain, sharpening) are real but modest.
• Grain not validated by measurement. On the sky of photo 1013 at 2560 px, the grain measure does not separate the styles (2.4 here, 2.3 Tri-X, 2.1 Acros 100 II, 2.5 base).
• Few sources. Reviews of a film discontinued around 2013 are scarce and disagree on the shadows.
• darktable’s grain is procedural noise: it imitates fine grain, not the shape of the crystals.

Tips

• Apply it early. If you plan to fine-tune the tone curve, sharpening or grain yourself, apply the style first.
• See the spectral conversion alone by switching off the tone curve, sharpen and grain modules the style set.
• Back to color: switch the main color calibration back on and switch off the “N&B” instance.
• Installation: see Install and apply darktable styles.