White balance presets¶
Upgrade the camera firmware (use a full, known reliable battery), be aware that it can brick your camera if done improperly (having the latest firmware is preferable, but not critical, if you are uncomfortable with the risks involved in upgrading your camera you should not attempt it).
Shoot a single RAW file for each of the camera's white balance presets (make sure you don't have any white balance finetuning enabled). Image content doesn't matter. This is usually 5-10 shots. Make sure you have a recent version of ExifTool installed. You can download the latest exiftool from http://www.sno.phy.queensu.ca/~phil/exiftool/ I find the version in Ubuntu is too old.
Some cameras optionally offer the ability to tune their white balance presets. You can include these as well (but the numbers of shots increase rapidly, as there are typically 5-10 base presets, offering as much as 19 steps of finetuning per preset). For the time being you need to shoot either all or none of the finetuning steps as darktable hasn't implemented finetuning interpolation yet. If you do, use only the blue-amber axis, leave the green-purple axis centered (0). This will enable the fine tune slider in the white balance module of darktable.
There's a few different scripts floating around to help you extract the white balance info from your images. The ruby version in the darktable tools directory seems to be the most up-to-date.
sudo apt-get install git ruby ruby-nokogiri libimage-exiftool-perl
mkdir wd && cd wd
tar xvzf /Downloads/Image-ExifTool-10.36.tar.gz # this is the exiftool download
git clone https://github.com/darktable-org/darktable.git
cd <directory with your white balance images>
rm -rf ~/white_balance.txt
for file in *; do ~/wd/darktable/tools/extract_wb "$file" >> ~/white_balance.txt ; echo >> ~/white_balance.txt ; done
Now, have a look in the ~/white_balance.txt file. You will see the extracted white balance information for each image that you made. For me, I got more than one line per image, so I had to go through and select the one that was the setting that I set the camera to. Delete the other lines so you end up with one line per image. If you did the image fine tune, you may need to update the column that specifies the fine-tune.
Add a comment to the top of your file with camera name and version like this:
/* Fujifilm X-T10 Firmware Version 1.21 */
Now, you can either just post this info into a redmine issue:
Or you can test them out first by copy/pasting them into the source code of darktable and building and installing to test. If you're running darktable 2.0.x, the instructions are here:
Version 2.2 rc is here:
After you check out the tag for the version you want to build, you need to copy your new white balance values into this file:
Then you build and install, and run your newly installed darktable by doing:
Make sure you back up your database before running your modified darktable version though!
cp -a ./darktable ./darktable.bak