Question about White Balance in darktable

Software darktable
1

I have what is hopefully a quick question about how the color pickers work in “color calibration” and “white balance” modules in darktable. A while back when the new white balance workflow came out, I read a lot of threads about it, and read the docs for both modules, and felt like I had a basic understanding. However, when editing some pictures this week I’m a little confused by the behavior, and hope someone can clear it up for me.

I took some photos outdoors in morning light with a whiteboard. I figured that using this whiteboard as a starting point for white balance would be reasonable. To do this with the “color calibration” module I,

  1. set “white balance” module set to “camera reference”.
  2. use the color picker in “color calibration” to select a portion of the whiteboard.

This results in a very yellow color cast, and if I reselect the area using the color picker, I can see this non-neutral tone on the board.

ColorCalibrationApproach
ColorCalibrationApproach1412×996 248 KB

If I go back and try again with only “white balance”,

  1. disable “color calibration”.
  2. set “white balance” to “detected from area” and select roughly the same portion.

This result appears much more neutral and the area used is a neutral color as confirmed by the color picker.

WhiteBalanceApproach
WhiteBalanceApproach1412×824 196 KB

The documentation for both modules seems to indicate both workflows should result in similar outputs?

  • “color calibration” - “Use the color picker (to the right of the color patch) to select a neutral color from the image or, if one is unavailable, select the entire image. In this case, the algorithm finds the average color within the chosen area and sets that color as the illuminant.” (Docs)
  • “white balance” - “Draw a rectangle over a neutral color in the image to calculate white balance from that area.” (Docs)

I imagine I’m just misunderstanding something about how white balance is intended to work in darktable. Hopefully someone can point me towards some resources, or clear up my misunderstanding. Thanks in advance!

Images are processed using darktable 4.8.1 on MacOS. Source RAW image for those interested in duplicating my process: DSC08364.ARW (24.0 MB)

All images in this post are original work and published as CC0.

1 Like
2

Did you check that your area color mapping has a neutral sample (chroma = 0?). That setting survives resetting the module, even restarting darktable. It often fools people (it did me, when I wrote the original version of this text).
image

With DT master (but also on 4.8), the new white balance + color calibration combo uses white balance in the recently introduced as shot to reference mode.
That gives this result:

image
image1650×1027 416 KB

I normally switch color calibration to in camera (I even have an auto-applied preset for that). It sometimes introduces a tiny change, if color calibration thinks you are close to one of the standard illuminants, and pulls you there. No difference this time:

image
image1650×1027 412 KB

Picking from the board is very close to neutral:

image
image1650×1027 416 KB

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3

Thank you!

I had a slight orange color selected in the “area color mapping” menu. I must have used it at some point in the past, and forgotten all about it. Definitely surprising that it doesn’t reset with the module or restarting darktable. I appreciate the help!

4

It is designed not to reset so you can use the same value for multiple images.

1 Like
5

That makes sense. I use the same menu in the “exposure” module frequently, but hadn’t made the “measure/correct” connection in “color calibration”. I wonder if some slight UI affordance might be helpful for indicating when the “correction” area mode is set to a non-default setting.

ColorCalibrationApproach

6

That’s coming in the next version.

4 Likes