How to measure the effects of profiling and wrong profiles?

[Paapaa Poopoo]

I have a 2017 15″ MacbookPro and i1display Pro Retail. Using the latest DisplayCAL (3.8.9.3)

1. Switched Night Shift off.
2. I Calibrated and profiled the display using LCD PFS Phosphor WLED IPS correction at 160 cd/m2.
3. Profile quality was High, 425 patches, Auto-optimized

After installing the profile (saw visual difference to the default profile “Display P3”). I ran the Measurement report and got something like 0.43 average dE*00 and 1.42 maximum.

Now I wanted to test how this profile actually performs compared to other incorrect profiles. I switched the profile using the macOS “Preferences->Display->Colour” to ACES CG Linear (gives very dark, horrible image, totally unusable, visual differences are dramatic). Then I ran the Measurement report again, still got something like 0.7 average dE with 2.4 maximum. Next I used profile ROMM RGB: ISO 22028-2:2013 which gives horrible purple color instead of normal blue. Again, the avg was 0.5 and max being 1.1 (even better than with the correct profile???). Note: I did not touch the “Settings” selection in DisplayCAL. It always had my original real profile shown there.

Questions:

1. Am I testing the output of these totally incorrect profiles correctly? I saw the image change when switching profiles. So something happened.
2. Am I interpreting the report correctly?
3. Why on earth do those horrible images still give such a low values for deltaE? I’d have guessed a much larger average deltaE. I’m probably doing something wrong here.

Reports are attached.

• This topic was modified 4 years, 4 months ago by Paapaa Poopoo.
• This topic was modified 4 years, 4 months ago by Paapaa Poopoo.

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[Vincent]

1. You are testing the same custom made profile all the time.
   If you wish to evaluate your screen against other profiles make sure that DisplayCAL is set to “Settings:<current>”, close it, then set profiles to that display in OS settings, but I’m not sure if this breaks dedault settings for calibration/profilling due to all the bugs in the faulty macOS color management engine.
   Another way to do that is to use simmulate a profile + setting that profile as display profile in Verification tab settings, but some users may leave this settings all the time, so future verifications may look bad. Make sure to undo that after measuremnt report is finished.
   The ONLY profile that can be close to custom made is default macOS profile to your display (P3 D65).
2. For me the fastest way to evaluate a measurement report is
   -check that white is white (Measured vs. assumed target whitepoint ΔE*00), but due to all the bugs & faults in macOS you cannot correct that without loosing other things, so by default DisplayCAL does not correct it (hence it’s a NO PASS)
   -neutral grey, just check RGB + gray balance, the lower the range the better
   -RGBCYM coordinates + a*b* plot to check if user chose and emulated gamut OSD mode or something like that (not needed for apple screens)
   -contrast
   Yours seems good if we exclude whitepoint. Custom profile made by you and its GPU calibration seems good.
3. DisplayCAL and OS settings are configured to different things, read 1)

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