Color calibration in Linux

DisplayCal is pretty automatic.

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Good to know! I’m hoping all this will help me to be less nervous next time I send stuff off to be printed…

with a caveat, at least in my experience. I have a ColorHug2 (bought because it’s both affordable and because I wanted to support free/open solutions), and I had to struggle quite a bit with DisplayCal to get good results. The defaults were producing quite bad output to my eyes.

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What did you struggle with?

Wait half an hour after turning your screen on, let it warm up. Run the latest DisplayCal. Select “Office & Web”, in the Calibration tab set whitepoint to a color temperature of 6500K and set a custom white level of 120cd/m² (if your monitor can go that bright - you can measure to find out).

If you select the “Photo” preset it will set the whitepoint to 5000K which will make your screen look too warm under normal conditions unless you’re working with a D50 light booth.

Leave everything else at default.

You can optionally enable perceptual mapping by clicking on the gear icon next to “Profile type” in the “Profiling” tab, but WARNING! Some programs, for example all versions of Geeqie except for git, will use the perceptual intent if the profile supports it without giving you an option to not do that, and since perceptual intent shifts all colors your images may look whack. My advice is to keep perceptual mapping disabled until you both need it and know that your programs work correctly.

Calibrate and profile. If things look good, then in the Profiling tab you can increase the patch count of the test chart from 175 to something like 1148. The time it takes will change from 7 minutes to 41 minutes and you will end up with a good quality profile.

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red color casts in the generated profile. They are sort of a known problem, especially for version 1 of the colorhug. I have colorhug2 but found it to be still the case. After some digging, it seems that the issue is due to an inappropriate (for my screens, at least) factory calibration matrix. DisplayCal has now a built-in “hack” to work around this, by setting the instrument mode to “Auto” (only available for colorhugs). Then it gives decent results, but you are forced to use the white point and the white levels that are “native” to the display. Another thing that I found (again, by trial and error, and judging only with my eyes) is that for poor quality screens (like that of my old laptop) using a “simpler” matrix-based profile gives more consistent results than a supposedly more accurate LUT-based one. Again, this is not the default.

But as I said above, YMMV quite a lot with a different calibration device.

@Morgan_Hardwood Thank you for this! It’s likely going to save me a lot of headaches!

@Isaac I am wondering how did Pantone Huey work for you. Did you like the results?

I am wondering if anyone used this method:

I am going to try it on linux

Yes, it worked very well. I had to run the profiling and calibration routine a few times before I got the hang of it and achieved the best results, but in the end it was very easy.

@Andrius do you have a link to the software? I can compare the smartphone result with that from a proper colorimeter when time permits.