I’ve used Darktable for a while, but never really got into any depth on the subject of colour management. I’ve tended just to leave everything as default. However, I’ve recently got a wide-gamut display which has prompted me to get my head around things a bit more, and I’ve been doing a few experiments in Darktable to this end, but I don’t feel confident that images are being displayed as they should be.
I’ve read through quite a few other threads, some of which have helped me sort some things out, some of which have ended up getting into technical detail beyond my knowledge. There are many mentions of problems involving colour profiles on macos but I’m unclear whether these are still ongoing.
I’ll try and describe three problems as starters:
Problem 1: Darktable doesn’t use my “system display profile” for its "display profile"
I have a display that should be able to display, near enough, the AdobeRGB gamut. I have confirmed this in other applications using a test image (where a symbol is only visible if the saturated reds are not clipped out).
- I noticed that the test image would not display correctly in Darktable if I selected my “system display profile” in the menu of options that is accessible by right-clicking on eg. the softproof button.
- The image would appear to display correctly if I chose “AdobeRGB (compatible)” instead, which is much as expected, as my monitor’s profile approximately matches the AdobeRGB one.
- However I want to try and see things displayed as accurately as possible, and I have a calibrated profile that I made for my monitor using a colorimeter and DisplayCAL software. This is the profile I wanted to use. It’s the profile I have set as the display profile in macos settings, so it’s the profile that Darktable ought to use when I select “system display profile”
- Thanks to some information in other threads I eventually worked out that by adding my calibrated custom profile to a certain config folder (*see below), I could make it appear as an option in that “display profile” dropdown menu, and I could select it.
- So…this problem is partly solved but…
Problem 2: Darktable produces different results using my calibrated display profile, compared to other apps
- Having worked out how to access my calibrated profile and set it under “display profile”, I noticed that Darktable was not displaying images the same as other applications (eg Affinity Photo and mac Preview). It was displaying them with visibly less saturation.
- I also note that if I change between my calibrated profile and the standard “AdobeRGB” one, the “AdobeRGB” one looks more saturated. But I don’t think this should be the case.
- So, is the error in Darktable?
- Or is it user error - is some other setting that I need to adjust?
- Or is it the other apps that are doing it wrong? It seems unlikely that they would both agree on a “wrong” result.
Problem 3: “Gamut Check” produces unexpected results
- My understanding is that this should highlight (in cyan) all pixels in an image that are not within the gamut of whatever I have selected as “softproof profile” in the right-click menu. Is that correct?
- If I open an image with an sRGB colour profile assigned to it, Darktable should show me an image that contains no pixels outside of the sRGB colour space. Again, have I got that right?
- Now, if I choose “sRGB” as my “softproof profile”, and click on “gamut check”, I shouldn’t see any pixels highlighted, because no pixels should be out of gamut. Is that correct?
- However: what actually happens is that I see many pixels in the image highlighted in cyan. Once again, it appears to me that either Darktable is doing something wrong, or I am.
I’d be grateful for comments on any of these problems.
If the answer is simply that colour profiles just don’t work properly in Darktable on macos then I guess I’ll just have to give up using it for colour critical stuff. It would be useful to know this is the case before I spend more time trying to get things working though.
*steps to make a custom ICC profile available as a “display profile” in Darktable - I’m putting this here in case it’s useful to any other confused Mac users who come across this thread:
- make sure you have “hidden folders” switched to visible in macos (press cmd + shift + . to toggle this on or off)
- Find on your hard disk users / [your user account] / .config / darktable
- If it doesn’t already exist in that darktable folder, create one called “color” and then a subfolder in “color” called “out”
- Put a copy of your calibrated ICC profile in that folder, “out”.
- Restart Darktable and it should now show up as an option.