Having set the white balance using the eye dropper on a calibrite colour checker, I selected the same source with color picker to discover that it records the RGB as 186 197 201.
In order to achieve equal RGB with color picker I must add 532 to the temperature and deduct 0.024 from the tint.
I am sure that I have have done this in the past and the results have concurred.
What am I getting wrong?
Have you changed the histogram space, or even the display profile?
I wouldn’t know how to do either.
Here’s the RAW file in case that helps…
DSD02008.ARW (81.6 MB)
DSD02008.ARW.xmp (13.2 KB)
This file is licensed Creative Commons, By-Attribution, Share-Alike.
You can search the manual, this site and the web… I’m not at my computer now.
https://darktable-org.github.io/dtdocs/en/module-reference/utility-modules/darkroom/soft-proof/
And
https://darktable-org.github.io/dtdocs/en/module-reference/utility-modules/darkroom/soft-proof/
I have my histogram profile set to sRGB. But don’t expect a 1:1 match with the card’s markings. Because if the involvement of the display profile, they may never match the card, but that does not mean the output won’t be correct.
Does the card come with instructions as to what processing should be used to obtain the indicated colours? You may want to disable filmic and sigmoid, and go fully linear.
Another way to use a ColorChecker is:
https://darktable-org.github.io/dtdocs/en/module-reference/processing-modules/color-calibration/#extracting-settings-using-a-color-checker
Just to be sure, you are then using the Display Referred workflow? So you’re not using the Filmic or Sigmoid module, right?
Apologies. By saying “I wouldn’t know how to do either” I intended to indicate that I have never ventured into darktable’s hidden depths, so it is unlikely that I will have ever changed such things.
I may have clicked the Softproofing button in error at some point, but it appears to be set at the defaults…
I did try disabling filmic before posting, and whilst the RGB numbers change to 200 213 220 they still seem short of neutral.
I have the workflow set to none but filmic was enabled in this instance.
With filmic RGB 186 197 201
Without filmic RGB 200 213 220
Do you use only white balance, or white balance in conjunction with color calibration? In the second case, leave white balance at its default settings, and use the picker in color calibration to set white balance.
I personally struggle to assess white balance so I typically use a white card and white balance’s eye dropper.
When I reset white balance and used color calibration’s eye dropper, the color picker indicated a neutral RGB 210 210 210
However, disabling color calibration and returning to white balance’s eye dropper I get RGB 200 213 220
Note: I have deleted spurious paragraphs from this post to avoid any confusion further down the line.
I have absolutely no idea what is going on but darktable is now behaving as expected.
When I select the calibrite card using white balance’s eye dropper, and then select the same area of the card with color picker, I am now getting RGB 211 211 211, which is as expected.
The only changes I have made since my original post are…
I have left and right clicked the softproofing button, but not changed anything within. Doing this had no impact at the time.
I have reset white balance but I reset this (and my PC) several times before my original post.
I have enabled color calibration, and used its eye dropper as described above, but this is once again disabled.
At some point I changed color picker from min to mean. Subsequent min/mean/max tests do produce different readings but the RGB readings always remain in balance.
So you may had the softproofing activated, you should have a message displayed bottom-left in darkroom when it is activated. Anyway, issue solved.
