processing

Control how images are processed.

🔗image processing

always use LittleCMS 2 to apply output color profile
If this option is activated, darktable will use the LittleCMS 2 system library to apply the output color profile instead of its own internal routines. This is significantly slower than the default but might give more accurate results in some cases.

If the given ICC is LUT-based or contains both a LUT and a matrix, darktable will use LittleCMS 2 to render the colors regardless of this parameter’s value (default off).

pixel interpolator (warp)
The pixel interpolator used for rotation, lens correction, liquify, crop and final scaling.

Whenever we scale or distort an image we have to choose a pixel interpolation algorithm (see wikipedia for details). For warping modules, darktable offers bilinear, bicubic or lanczos2. In general, bicubic is a safe option for most cases and is the default value.

pixel interpolator (scaling)
The pixel interpolator used for scaling. The same options are provided as for the warp modules, but with the addition of lanczos3.

lanczos3 can cause pixel overshoots leading to artefacts but sometimes gives a more crisp visual appearance. This option is therefore only provided for transforming (scaling) algorithms and is the default value.

3D lut root folder
Define the root folder (and sub-folders) containing Lut files used by the lut 3D module
auto-apply pixel workflow defaults
Choose which modules and module order to apply to new images by default:

  • scene-referred workflow (default) assumes that most processing will be performed in a linear RGB color space. Selecting this option will automatically enable the filmic rgb and exposure modules and will set the pixelpipe order to v3.0 which is the (scene-referred) order defined for darktable 3.0 and later.

    The exposure module will include an automatic adjustment of +0.7 EV to adjust the mid-gray to match that of the majority of SLR cameras. This adjustment can be overridden with an automatically-applied preset if the default produces consistently dark images for your camera.

    Finally, this setting automatically enables the “compensate camera exposure” option in the exposure module to adjust the global brightness appropriately in cases where the camera’s exposure compensation dial was used.

  • display-referred workflow assumes that most processing will be performed in the Lab color space and is the legacy mode from darktable 2.6 and earlier. Selecting this option will automatically enable the base curve module and set the pixelpipe order to the legacy (display-referred) order used by default up to version 2.6.

  • none will not enable any modules by default and will set the pixelpipe to the v3.0 (scene-referred) order defined for darktable 3.0 and later.

auto-apply chromatic adaptation defaults
Choose which module is responsible for performing white balance adjustments (chromatic adaptation) by default. Select “legacy” (default) to perform basic chromatic adaptation within the white balance module only. Select “modern” to use a combination of the white balance and color calibration modules to perform modern chromatic adaptation with improved color science. These settings are applied by default to new edits and will not impact old edits.
auto-apply per camera basecurve presets
Use a per-camera base curve by default (if available) instead of the generic manufacturer one. This should only be used in conjunction with the display-referred workflow defined above (default off).
detect monochrome previews
Enable this option to analyse images during import and tag them with the darkroom|mode|monochrome tag if they are found to be monochrome. The analysis is based on the preview image embedded within the imported file. This makes for a more convenient workflow when working with monochrome images, but it slows down the import, so this setting is disabled by default.
show warning messages
Enable this option to display warning messages in processing modules where non-standard and possibly harmful settings have been used in the pipeline. Such messages can sometimes be false-positives (because of intentional non-standard settings) and can be disregarded if you know what you are doing. Disable to hide these warnings. (default on).

🔗cpu / gpu / memory

darktable resources
Choose how much of your system and graphics card (GPU) memory will be used by darktable. Four options are provided by default:
  • small takes roughly 20% of your system memory and 40% of your GPU memory. This might be acceptable on very large systems, especially if you’re not exporting images. Mostly, though, this can only be recommended if you are using a lot of other demanding applications at the same time as darktable.
  • default takes roughly 60% of your system memory and 70% of your GPU memory. This mode is recommended if you’re not exporting a lot of images, have at least 16Gb of system memory and 4Gb of GPU memory, and also are running a lot of other application at the same time as darktable.
  • large takes roughly 75% of your system memory and 90% of your GPU memory. This is the best option if you are only using darktable on your system and/or are exporting a lot of images.
  • unrestricted is not generally recommended. In this mode darktable may attempt to use more memory than your system has available. This might be possible if your system uses swapping when all of its system memory is taken, but it could lead to system instability. Use this mode with care, only when exporting very large images that darktable cannot otherwise handle.
See the memory & performance tuning section for more information.
prefer performance over quality
Enable this option to render thumbnails and previews at a lower quality. This increases the rendering speed by a factor of 4, and is useful when working on slower computers (default off). This also improves the performance of slideshow image rendering.
enable disk backend for thumbnail cache
If activated, darktable stores all thumbnails on disk as a secondary cache, and thereby keeps thumbnails accessible if they are dropped from the primary cache. This needs more disk space but speeds up the lighttable view as it avoids the reprocessing of thumbnails (default on).
enable disk backend for full preview cache
If enabled, darktable writes full preview images to disk (.cache/darktable/) when evicted from the memory cache. Note that this can take a lot of storage (several gigabytes for 20k images) and darktable will never delete cached images. It’s safe to delete these manually if you want. Enabling this option will greatly improve lighttable performance when zooming an image in full preview mode (default off).
activate OpenCL support
Your GPU can be used by darktable to significantly speed up processing. The OpenCL interface requires suitable hardware and matching OpenCL drivers on your system. If one of those is not found the option is grayed out. Can be switched on and off at any time and takes immediate effect (default on).
OpenCL scheduling profile
Defines how preview and full pixelpipe tasks are scheduled on OpenCL enabled systems:
  • default: the GPU processes the center view pixelpipe; the CPU processes the preview pipe,
  • very fast GPU: both pixelpipes are processed sequentially on the GPU.
  • multiple GPUs: both pixelpipes are processed in parallel on different GPUs – see the multiple devices section for more information,
tune OpenCL performance
Defines how darktable will attempt to tune OpenCL performance for your system. The following options are provided (default nothing):
  • nothing: do not attempt to tune OpenCL performance.
  • memory size: this parameter currently (by default) applies a fixed 400MB headroom to all devices and assumes the remainder (total device memory less 400MB) is available for OpenCL module processing. You can also choose to amend this value or have darktable attempt to auto-detect available memory by changing a parameter in your darktablerc file. Please see the memory & performance tuning section for more details. If you choose to enable auto-detection, switching this parameter off and on again will force a re-detection at the next pipe run.
  • memory transfer: when darktable needs more memory than it has available, it breaks your images into tiles, which are processed separately. When tiling, darktable frequently needs to transfer data between system and GPU memory. This option tells darktable to use a special copy mode (pinned memory transfer), which can be faster, but can also require more memory on some devices. On other devices it might degrade performance. There is no safe general way to predict how this option will function on a given device so you will have to test it for yourself. If you have multiple devices, you can switch pinned memory transfer on or off on a “per device” basis by directly editing your darktablerc file.
  • memory size and transfer: use both tuning mechanisms.
See the memory & performance tuning section for more information.

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