Darktable Film Simulation Panel

A graphical panel in darktable's lighttable and darkroom for applying presets.

This darktable extension consists of

• a Lua script that adds a "Film Simulations" panel to the darkroom and lighttable
• a user.css and a number of icons for putting images on the panel's buttons
• a number of styles, which the buttons apply

The supplied styles are:

• Fuji/Provia
• Fuji/Astia
• Fuji/Velvia
• Fuji/Classic Chrome
• Fuji/Pro Neg High
• Fuji/Pro Neg Std
• Fuji/Eterna
• Ricoh/Ricoh Standard
• Ricoh/Positive Film
• Ricoh/Negative Film
• Ricoh/Vivid
• Ricoh/Retro
• Ricoh/Bleach Bypass (not included in panel)
• Ricoh/Cross Processing (not included in panel)
• 4 × Shadows (simple tone curve RGB adjustments)
• 4 × Exposure (simple exposure adjustments)
• DR100, DR200, DR400 (tone equalizer presets for raising shadows/midtones by 0/1/2 EV)

Not all styles are applicable to all images. Fuji and Ricoh styles are targeted to Fuji/Ricoh cameras, and won't apply to others. This is implemented by simple EXIF-maker matching with the style prefix (Fuji/, Ricoh/) in the lua script.

Adding a new button to the Film Simulations panel involves:

• adding the button in FilmSimPanel.lua using darktable.new_widget, and giving it a unique name
• adding the button name to the class at the beginning of user.css to style it as a panel button
• adding a unique entry at the end of user.css to give it an icon

Installation

Start darktable and use import action of the styles panel in the lighttable view. Select all files in the styles directory of this repository for import.

After that, the styles should be already applicable.

Close darktable (or make sure you restart the application at the end of installation).

The directories icons and lua must be copied to darktable configuration directory (e.g. ~/.config/darktable, ~/.var/app/org.darktable.Darktable/config/darktable or C:\Users\<username>\AppData\Local\darktable).

If you have changed user.css e.g. in the general settings tab of darktable preferences, you have to add the content of user.css manually.

Otherwise, the unmodified standard user.css in darktable configuration directory can be overwritten with the file user.css of this repositoy.

You may still need to create luarc in the configuration directory.

Finally, activate the FilmSimPanel lua script by adding this to luarc:

require "contrib/FilmSimPanel"

(This description should work for darktable 4, but at the time of writing has only been tested with darktable 4.4.2 on the current Linux Arch OS.)

Usage

The styles are meant to be applied after Sigmoid with 1.5 Contrast, 0 skew, per-color processing with 50% preserve hue (as tested in darktable 4.2.1).

Known Issues

In some versions of Darktable, applying a style using darktable.styles.apply in the darkroom crashes darktable. The reasons for this are as of yet unknown. A bug report has been filed. You can apply the styles without issue from the styles menu, or in the lighttable panel.

The Film Simulation Panel currently works around this by using the darktable.gui.action interface instead if in the darkroom view. This might behave strangely in edge cases, such as multiple images in the current selection, or if the style names contain untested characters (/ is appropriately escaped, but others might need escaping as well).

Background

The styles were compiled using darktable-chart:

• edit your darktablerc and set allow_lab_output=TRUE
• export each of the JPEGs in style_source as PFM (only available with the above edit)
• export the two RAF/DNG as PFM as well, make sure white balance is set on the middle grey patch, and that the input profile is in its default state, and that only a bare minimum of modules is active
• run darktable-chart or flatpak run --command=darktable-chart org.darktable.Darktable
• select the exported RAF/DNG and the supplied color_checker.cht in the first tab (and adjust boundaries to match image, increase scale if necessary)
• select the exported JPEG in the second tab (also adjust boundaries)
• calculate and export in the third tab. If the difference is inf, check the masks in the first and second tab. I like to export only tone curve and color lookup table. Don't forget to set a style name.

The supplied target images were shot in sideways midday sunlight, white-balanced on a sheet of white paper. They were processed in-camera to the various film simulations.

When exporting the RAF/DNG target PFM, set up darktable to your preferred baseline. In my case, I want the style to apply after Sigmoid, so I include Sigmoid with my default settings in the RAF/DNG. As a fun diversion, you can mix and match source and target files as you please, for example, you can readily create a style for replicating Ricoh's "Positive Film" simulation from a Fuji camera.