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 +0.5 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).
auto-apply sharpen
Auto-apply the sharpen module to new images by default. This option is not recommended on cameras without a low-pass filter. (default on, requires a restart).
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

memory in megabytes to use for thumbnail cache
In order to speed up the display of film rolls, darktable stores image thumbnails in a cache on disk (primary cache) and loads it into memory at startup. This setting controls the size of the cache in megabytes. Needs a restart if changed (default 512MB).
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).
host memory limit (in MB) for tiling
In order to manage large images on systems with limited memory darktable does tile-wise processing. This variable controls the maximum amount of memory (in MB) a module may use during image processing. Lower values will force memory-hungry modules to process an image with increasing number of tiles. Setting this to 0 will omit any limits. Values below 500 will be treated as 500. Needs a restart if changed (default 1500).
minimum amount of memory (in MB) for a single buffer in tiling
If set to a positive, non-zero value, this variable defines the minimum amount of memory (in MB) that darktable should take for a single tile. Needs a restart if changed (default 16).
activate OpenCL support
darktable can use your GPU 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;
  • multiple GPUs: both pixelpipes are processed in parallel on two different GPUs;
  • very fast GPU: both pixelpipes are processed sequentially on the GPU.

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