Hello everyone,
I use Darktable 4.2.1 on Ubuntu 22.04 LTS and have the problem when I use the pipette in the color callibration module that the image becomes black and CCT cannot be calculated.
I was now able to circle the error in so far that it has to do with the darktabblerc file. So I had a new file created with which the pipetting function in the color calibration module works and wanted to compare the functioning file darktblerc with the old, non -functioning file. But since there seems to be some differences, I need an explanation of what the individual parameters in the darktlerc file mean. Is there something like that and if so where?
I am very grateful for any help and please excuse my bad English.
Sunny greetings Hoerianer
As (for me) darktablerc is a text file of over 1000 lines, explaining all parameters would be “a bit” too long for a post here.
Perhaps you can post the differences you observe?
Or, there’s always another option: dig into the source code for the interesting parameters.
Try
Search in GitHub issues (closed), because the blank screen was something that was recently fixed. I dont remember if it is part of 4.2.1 or 4.4
Fixed in master so for 4.4
Hello,
first sorry for the late reply, too much work all day 
@g-man I was a bit naive and didn’t consider the size of the files. I am still working on a solution to show the differences, there are some.
@kofa Thank you for the note on this file but I don’t know exactly what to do with it or where I should put it down in the Darktable directory.
I’m a new user and so i can only answer to two members, so I continue to write here…
@g-man Not the whole screen becomes black but only the picture. Everything else fits.
@hannoschwalm I only have 4.2.1. May I ask what the fix has to do with the darktablerc file or how it is related? Because when I rename the darktablerc file and restart Darktable it will be created again and everything works. I am therefore eating the idea that there is something to do with the darktablerc file. Sorry I’m just a user, not a developer 
sunny greetings and thy for your help
hoerianer
Hi,
you shouldn’t put it anywhere. You can simply read it.
For example:
<dtconfig dialog="collect">
<name>plugins/lighttable/collect/history_max</name>
<type min="1" max="50">int</type>
<default>10</default>
<shortdescription>number of collections to be stored</shortdescription>
<longdescription>the number of recent collections to store and show in this list</longdescription>
</dtconfig>
This mean the setting belongs to the collections dialogue, its name is plugins/lighttable/collect/history_max. The type is an int (integer, whole number), the minimum/maximum/default values are 1, 50 and 10, respectively, and the descriptions are what you can read here.
Or take:
<dtconfig prefs="processing" section="cpugpu">
<name>resourcelevel</name>
<type>
<enum>
<option>small</option>
<option>default</option>
<option>large</option>
<option>unrestricted</option>
</enum>
</type>
<default>default</default>
<shortdescription>darktable resources</shortdescription>
<longdescription>defines how much darktable may take from your system resources.\n - default: darktable takes ~50% of your systems resources and gives darktable enough to be still performant.\n - small: should be used if you are simultaneously running applications taking large parts of your systems memory or OpenCL/GL applications like games or Hugin.\n - large: is the best option if you are mainly using darktable and want it to take most of your systems resources for performance.\n - unrestricted: should only be used for developing extremely large images as darktable will take all of your systems resources and thus might lead to swapping and unexpected performance drops. use with caution and not recommended for general use!</longdescription>
</dtconfig>
It’s a processing setting (on the config UI), which can have the listed (enumerated → enum) values, the default being default, and you have the short and long descriptions, again. Those you can also see on the UI, when you hover over the element.
There will be settings in darktablerc that you won’t find on the UI, and maybe settings that are not documented here, either. But it’s a start.
However, as @hannoschwalm has told you, your issue was caused by a bug (even if it was triggered by some configuration value).
@kofa Hoi,
thank you very much for this detailed information. Then I will probably do “youth research”. So workaround up to 4.4 comes out, I can always have the file created again. Thank you again and stay healthy. Sunny greetings Hoerianer