Film negatives
The Negative panel turns a photo of a film negative, taken with a camera or a scanner, into a positive. It runs darktable’s negadoctor module, which inverts the film by its densities and then simulates printing it on paper. Open it with the film strip button on the right-hand rail.
Before you start
- Photograph the whole frame, with some of the border. The unexposed film around the picture (the orange or clear edge, not the black frame gap) is what the conversion measures first.
- Keep the light even and the negative clean. Dust and scratches read as the darkest or brightest parts of the film and throw the automatic values off.
- Expose the scan to the right. Make the film border as bright as it goes without clipping. A color negative’s orange mask lets little blue through, and an underexposed scan’s blue sinks into the sensor’s noise in the film’s densest parts, the scene’s highlights, which shows as noisy, cast shadows in the print.
- Convert first, then edit. Converting changes what Basic’s tools work on, so do it before the rest of the edit.
What converting turns off
Opening the panel on a photo that is not yet converted warns you what changes. Some of Basic’s tools work on the light before the negative is inverted, or do the job the print now does, so a converted negative turns them off:
- Temp and Tint (darktable’s color calibration)
- Exposure, Whites, Blacks, Profile and Auto (exposure and the tone mapper, AgX or sigmoid)
- Dehaze (haze removal)
They are greyed out, marked “set in Negative”. The panel’s own Exposure, White Point, Blacks and Neutral Highlights stand in for them.
Contrast and Saturation keep working, on color balance rgb, and Highlights and Shadows on shadows and highlights: modules that run after the conversion. Everything else (the tone curve, HSL, color grading, detail, effects, masks, crop) works as on any photo.
The warning has a “Don’t warn me again” box; Preferences › General › Warn before converting a negative turns it back on.
Converting a negative
- Film Type. Choose Color or Black & White. Black & White also sets Basic’s Treatment to Black & White.
- Pick Film Border. Click it, then drag a box over the unexposed film border, clear of any pre-exposed edge or printed numbers. This converts the photo. Its border color shows in the swatch beside the button.
- Pick Photo Area. Drag a box over the picture inside the border, clear of dust. White Point, Black Point, Blacks and Exposure are set from it. Until you pick one, the conversion reads the whole frame bar a thin edge.
While an eyedropper waits for a box, the photo shows uncropped, so the film border can be reached; your crop comes back once the pick is read. Crop the border out with the Crop tool when you are done.
The controls
Each control has an eyedropper beside it that sets that control alone from a box you drag. The tooltips give darktable’s own names, to match its manual and tutorials.
| Control | What it does | Where to pick |
|---|---|---|
| White Point | the film’s densest part, which becomes white: left brightens the highlights, right darkens them | the brightest part of the scene |
| Black Point | where the scan’s darkest tones sit: left brightens the shadows, right darkens them | the film border, or the whole photo |
| Neutral Shadows | takes a color cast out of the shadows (color film) | the film border, or a shadow that should be neutral |
| Neutral Highlights | the white balance (color film) | something white or gray |
| Exposure | the print’s overall brightness; picked, as bright as it goes without clipping | the brightest part of the photo |
| Contrast | the print’s contrast | |
| Blacks | how deep the blacks go; picked, what should be pure black | the film border, or a dark part of the photo |
| Highlight Roll-off | where the brightest tones start to compress: lower is gentler |
Set Neutral Shadows before Neutral Highlights: the shadows’ correction moves the highlights too. Reset Color sets both back. Advanced holds the Border Color, Shadow Tint and White Balance as red, green and blue sliders.
Turn Off Conversion takes the photo back to the negative, with Basic’s tools as they were. Undo does the same.
A whole roll
Convert one well-exposed frame, then copy its settings to the rest of the roll: Copy… in the right-hand panel, tick Negative (it starts unticked), and paste onto the other frames. Each one is converted and its modules turned off as if you had converted it. A frame exposed very differently may need its own picks.
Export a positive to the library
Export to Library writes a separate positive beside the original, with the conversion and current edits baked in. It opens with normal editing tools available, so you can continue editing without the negative workflow’s restrictions. The original keeps its conversion edit. Preferences › General › Workspace › Converted negative format chooses losslessly compressed DNG (16-bit float), the default, or TIFF (32-bit float). The result opens automatically unless Open generated photos is off.
In darktable
The edit is darktable’s negadoctor module, with the modules above switched off, so darktable of the same version opens it the same. In darktable the controls are in negadoctor’s three tabs, under the names the tooltips give.
This page is part of immage's own docs, at v0.41.1. View the source on GitHub.