I'm trying to run the display/color calibration utility on my 2018 MacMini for a Dell U2415 monitor (I've also trued this with my BenQ PD2700Q with almost identical results) connected via DP and having a very hard time. I'm hoping I'm doing something wrong rather than the whole process being flawed.

I run into trouble at the very first gate... well second, technically. I am able to turn my contrast all the way up as instructed, but when I try to reduce the brightness so that the oval is just barely visible, I get down to 0% before the condition is met. The instructions say to decrease the brightness if the right half of the box appears lighter than the left. As you can see in this photo of my screen (taking a screen grab did not capture the darkness), this is the case, but I am already at 0% AND the entire screen is incredibly dark.

Dell U2415 with Contrast: 100% - Brightness 0%

I know the photograph doesn't really show anything accurately, but just for reference... to show how dark the Dell is, here it is with contrast at 100% and brightness at 0% (right half of box is still brighter than the left) next to my BenQ restored to factory defaults. At the very least, this should show how dark the Dell is with the instructions still telling me to decrease brightness.

Left: Dell with same settings as above. Right: BenQ restored to factory defaults

Has anyone else run into this? Or have any advice for getting at least ONE of my monitors calibrated for a halfway decent print preview?

1 Answer 1


The 'by eye' calibration is very approximate, even if you hold Opt as you click the Calibrate… button to gain more precise control over colour balance & gamma.

It's really difficult to screenshot this, for many reasons, including that any existing profile is bypassed as soon as you start into the assistant, yet the embedded profile in the screenshot is still the one your display is normally set to, but something like this is OK for starters.

enter image description here

Unless your display has a really offset gamma, the relative brightnesses of these elements really shouldn't change too much with brightness. If you can get closer using contrast, give that a go.
Without a meter you don't have an optimum 120cd/m2 brightness to aim for anyway, so this is always going to be just a rough calibration. I'd just start by setting brightness to look approximately like your other screen.

As you progress through the Assistant, you'll probably notice that it's really tough to find an exact match. Squinting to make the image blurred can help, but you'll find you have to waggle each slider to help you decide where the mid-point is, when it looks about OK.
You may even have to go through this two or three times, then pick the 'best' one afterwards. It is a very inexact science, doing it this way.

Honestly, though, even if you go through the advanced [hold opt] calibration, you are not going to get close enough for accurate pre-press, or even really web sRGB. You really need a hardware colorimeter/spectrophotometer for that.

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