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rynop2000 Author

Level 1

39 points

16" MacBook Pro blue pixel aliasing on external display

I have a new MBP 2019 16" with the AMD Radeon Pro 5500M 8 GB vid card.

When I plugged my LG UltraFine 5K display in via USB-C I noticed strange light blue aliasing around font and images.

Example (bad):

Here is the same text (in same window) but on the MBP built-in retina display:

It doesn't show up great here, but its very obvious to the naked eye.

It happens on everything (not just font):

What is strange is I do NOT see this issue if I change the display resolution scale to `2560x1440` or below in Display Settings:

I know it is NOT a problem with the external monitor, because when I plug it into my late 2018 15" MBP I do not see the problem.

I have a second 4K LG monitor plugged in at the same time, and it is not exhibiting this issue (no matter what resolution scale is selected).

I've tried:

- Disabling font smoothing

- Restarting

- Changing monitor color profiles

- Using f.lux

- Only plugging in the UltraFine 5k

Any ideas what this is called or how I might fix? This is SUPER annoying.

MacBook Pro 16", macOS 10.15

Posted on Dec 20, 2019 10:21 AM

Best reply

Podizzler

Level 1

4 points

Posted on Jan 22, 2020 8:53 AM

Brought it into the Apple Store again today. Associate had heard of the issue anecdotally. He acknowledges that it's some sort of bug; whether it's software or hardware is not clear yet. I have confirmed that the problem will not present itself if About This Mac does not show the AMD graphics card listed. Apple is not aware of how to fix this issue yet, at least in a widespread manner; I recommend if you're reading this to open the Feedback Assistant app and submit a bug report directly to engineering (if this isn’t available, maybe you need to go to https://beta.apple.com/sp/betaprogram/ Hopefully they will pressure test the issue and find that it's software related, and hopefully the fix will be presented in the form of a software update.

With the following steps, I was able to reproduce the issue on all three floor machines in my local Apple Store (one out of three only showed the issue flittingly):

- Click Apple > About This Mac

- If Graphics card section only reads the built-in Intel, open as many graphic-intensive programs as possible, such as the Adobe Suite, or even GarageBand.

- Close and reopen About This Mac. Make sure AMD Radeon Graphics card is shown in the list.

- Open Display preference pane.

- Resolution > Default for display

- Check True Tone on.

Now take note of cyan or baby blue aberration that happens on white lines on black, white type on black, or sometimes thin black lines on white. See: left vertical line of cursor, move slowly left and right. Top line of battery icon will show cyan, especially is Dark Mode is activated.

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16" MacBook Pro blue pixel aliasing on external display

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