Luminance issue with Late 2015 iMac

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    Topic: Luminance issue with Late 2015 iMac Read 724 Times
  • Clive Barber
    Clive Barber
    Posts: 3
    Computers & Displays
    on: September 14, 2019 at 4:34 pm

    Mac OS 10.14.6

    i1Profiler v 1.8.2
    i1 Display

    “Automatically adjust brightness” deselected in System Preferences

    Usual i1Profiler settings for my iMac:

    • GB-LED

    I recently noticed a Luminance issue when calibrating my Late 2015 27″ iMac. I don’t see the luminance level change when clicking through one profile to another, even when the luminance setting is drastically different.

    As a test today I created four identical profiles with the exception of luminance. I started off at 80L and went up to 150L but saw no brightness change on the display when clicking through each profile in the System Preferences window. According to i1Profiler I achieved my target and have created each profile successfully.

    What is also strange now is if I go to the ‘Display’ window in the System Preferences I can adjust the Brightness slider as normal. I can boost or dim the brightness of the display, BUT, going back into the ‘Color’ window and clicking on a colour profile shows no change to the display. In other words the colour profile does not rule, the brightness slider does. Whatever the ‘Brightness’ slider was set at overrules any profile.

    Any advice much appreciated.

    Thanks in advance.

    Clive Barber
    Clive Barber
    Posts: 3
    Re: Luminance issue with Late 2015 iMac
    Reply #1 on: September 16, 2019 at 10:57 am

    Solved. My error.

    My saved calibrated display profiles over the years always looked close to identical because they were created with the same settings. Everything has been good and I never played around with the brightness slider either. But for some reason a few days ago I lost the plot and decided as a test to create profiles with significant different luminance settings with the assumption that clicking on them will change the display luminance. Well obviously that didn’t happen.

    All these years thinking I understood the display calibration process but I was wrong. Luminance changes are hardware controlled. Now I know and won’t forget!

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