Improving and “installing” denoise profiles in darktable

This article desribes how to postprocess and install denoise profiles that have been manually created for darktable. By “installing”, I mean to make the denoise profile available in the productive darktable library, which is usually located at ~/.config/darktable/library.db .

Obtaining a denoise profile

There is already a very good tutorial and excellent tool support for determining a camera’s noise profile. The profiling produces two major artefacts:

presets.txt contains one or more array items that can used while compiling darktable
library.db an SQLite library that may be used to evaluate the new denoise profiles on the fly by running darktable as follows:

Shell

darktable --library library.db

1

darktable --library library.db

I will now describe how to optimize and export the denoise profiles from the SQLite library.

For visual inspection, I recommend the Firefox addin SQLite Manager. For batch processing, I use the command line tool sqlite3, which can be installed as follows:

sudo apt-get install sqlite3

1	sudo apt-get install sqlite3

The generated denoise profiles can be found with the following SQL query:

SELECT * FROM presets WHERE operation="denoiseprofile"

1	SELECT * FROM presets WHERE operation="denoiseprofile"

You recognize the camera that you just built the denoise profiles for in the name column. In this article, I use the Canon EOS 100D as a running example:

SELECT * FROM presets WHERE operation="denoiseprofile" AND name like "Canon EOS 100D %"

1	SELECT * FROM presets WHERE operation="denoiseprofile" AND name like "Canon EOS 100D %"

Postprocessing (optional)

Looking at the further columns, you will notice filter criteria such as model, maker, lens, exposure_{min,max}, aperture_{min,max},focal_length_{min,max}. The column filter determines whether (=1) or not (=0) each row is only displayed in darktable only if the current image matches the filter criteria.

The following SQL code adjusts the filter criteria for each denoise profile for the Canon EOS 100D separately. The values for model and maker have been extracted from the image information as shown in darktable.

UPDATE presets SET 
  model="Canon EOS 100D", /* same as the model recognized by darktable/exiv */
  maker="Canon",          /* same as the maker recognized by darktable/exiv */
  lens="%",<strong>               /* apply to any lens */</strong>
  exposure_max=3.4e+38,   /* maximum possible value -> always applicable */
  aperture_max=3.4e+38,   /* maximum possible value -> always applicable */
  focal_length_max=1000,  /* maximum possible value -> always applicable */
  filter=1                /* enable filtering, only show if applicable*/
  WHERE operation="denoiseprofile" 
  AND name LIKE "Canon EOS 100D iso %";
UPDATE presets SET iso_min=100,iso_max=100  
  WHERE operation="denoiseprofile" 
  AND name = "Canon EOS 100D iso 100";
UPDATE presets SET iso_min=200,iso_max=200  
  WHERE operation="denoiseprofile" 
  AND name = "Canon EOS 100D iso 200";
UPDATE presets SET iso_min=400,iso_max=400  
  WHERE operation="denoiseprofile" 
  AND name = "Canon EOS 100D iso 400";
UPDATE presets SET iso_min=800,iso_max=800  
  WHERE operation="denoiseprofile" 
  AND name = "Canon EOS 100D iso 800";
UPDATE presets SET iso_min=1600,iso_max=1600  
  WHERE operation="denoiseprofile" 
  AND name = "Canon EOS 100D iso 1600";
UPDATE presets SET iso_min=3200,iso_max=3200  
  WHERE operation="denoiseprofile" 
  AND name = "Canon EOS 100D iso 3200";
UPDATE presets SET iso_min=6400,iso_max=6400  
  WHERE operation="denoiseprofile" 
  AND name = "Canon EOS 100D iso 6400";
UPDATE presets SET iso_min=12800,iso_max=12800  
  WHERE operation="denoiseprofile" 
  AND name = "Canon EOS 100D iso 12800";x

UPDATE presets SET

model="Canon EOS 100D", /* same as the model recognized by darktable/exiv */

maker="Canon", /* same as the maker recognized by darktable/exiv */

lens="%",<strong> /* apply to any lens */</strong>

exposure_max=3.4e+38, /* maximum possible value -> always applicable */

aperture_max=3.4e+38, /* maximum possible value -> always applicable */

focal_length_max=1000, /* maximum possible value -> always applicable */

filter=1 /* enable filtering, only show if applicable*/