1 pixel verticle distortion line in middle of external monitor

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1 pixel verticle distortion line in middle of external monitor

Hi there,

I have a MacBook Air M1 2020. It's running 13.2.1, although the issue has existed in numerous earlier OS versions.

I have an external display connected to it. It's a Philips 346B1C. It's connected via USB-C.

The issue I am having is that down the vertical middle of the screen is a 1 pixel "line". It's not a visual line as such, but a distortion line. It causes a slight distortion of the display out. Such that if there is text there (which is almost always the case, the text at that position will be distorted. It's hard to describe.

I tried to take screenshots, but it doesn't show up in a screenshot. So what I've done is filmed it with my phone. It's not as obvious in the film as it is on the display, but it should at least give an idea of what I'm talking about. In the film I am moving the browser window left and right, so you can see the distortion line as it passes over the text. In the video I am keeping the line over the "on" of the word "question". So the line can be seen in any text under the vertical position. https://www.youtube.com/watch?v=HRjwW7w5Ghg

I thought it was a problem with the monitor (which I only bought about 5 months ago). When when I use the same monitor on a Mac Mini M1, the issue doesn't occur. So it appears to be something related to the MacBook Air.

I previously had a 27" Dell monitor on the MBA, and didn't have this issue.

Any suggestions on what might cause it, and what to do about it?

When reading particularly small text, it can distort the text sufficiently that it becomes hard to read. Which is why I'd like to resolve it if possible.

Thanks,

Jonathan

MacBook Air 13″

Posted on Mar 5, 2023 3:46 PM

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Answer 1

Top-ranking reply

OrigamiFan1

Community Specialist

Mar 7, 2023 2:02 PM in response to InspiredLife

Hello InspiredLife,

For help with the distortion when your MacBook Air is connected to an external monitor test adjusting the resolution. The steps below found in the article here can assist. Change your Mac display’s resolution

"Set the resolution for a connected display

If you have more than one display, additional resolution options are available after the other display is connected.

On your Mac, choose Apple menu > System Settings, then click Displays in the sidebar. (You may need to scroll down.)
Select the display you want to adjust, then select the resolution you want to use.
You may be able to turn on “Show all resolutions” to see additional resolutions for the display."

You can also test the issue while booted to safe mode. Start up your Mac in safe mode - Apple Support

If the issue remains, as you've isolated it to your MacBook Air, reach out to Apple Support directly to further assist.

Contact - Official Apple Support

Contact Apple for support and service - Apple Support

Best.

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Answer 2

Branta_uk

Level 7

32,666 points

Mar 7, 2023 2:28 PM in response to InspiredLife

Thanks to OrigamiFan1 for bumping this to the top where I noticed it. I looked at the spec and reviews for this display, which looks impressive until you notice a comment that refresh rate may drop from 100Hz with USB 2.0, to 60Hz if USB 3.2 is selected. That rang alarm bells when I noticed you are driving it with USB-C from your MacBook, and my first thought was the potential quality of USB-C cable.

Please be aware that many USB-C cables (including many Apple branded) are rated as "charge only" and may behave unpredictably at the high data rates required for your big screen display. I'm not saying this will be the cause, simply something you might need to check out.

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Answer 3

InspiredLife Author

Level 1

63 points

Mar 7, 2023 2:33 PM in response to OrigamiFan1

Thanks OrigamiFan1.

I did previously try adjusting the resolution, as it occurred to me that might have some effect on it. But it seems to persist across different resolutions.

I'll boot into safe mode and see what happens with that.

In the image attached below is a good example of when it's a nuisance by making text obscure. You can see the "d" on "end" looks more like a "c". Makes it hard when that's happening right through an email or page of text on web page.

Thanks very much. I'll post back with what I discover.

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Answer 4

InspiredLife Author

Level 1

63 points

Mar 7, 2023 3:32 PM in response to Branta_uk

Yes, that was a photo. I've take two more photos, using the macro feature on the phone, to eliminate focus issues the phone camera might have introduced due to it being so close to the subject.

It's interesting to see that in the USB 3.2 photo the positioning of the text and space between text elements moves (degrades, in my opinion).

It's especially obvious when I view the images in the same spot on my computer, and switch back and forth between them.

Neither looks as clear as I would expect. Although it still seems that USB 2.0 is clearer when I view the actual monitor from normal viewing distance. But I might be imagining that, as neither photo looks much better than the other.

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Answer 5

InspiredLife Author

Level 1

63 points

Mar 7, 2023 2:59 PM in response to Branta_uk

Thanks Branta_uk,

I appreciate you looking into that. It had occurred to me it could be refresh rate related, so I had played around with that previously. The only options I had in the display settings in macOS for this display are 75, 60, 30, which was odd to me, as I recalled when I bought it that it went to 100 Hz. It didn't occur to me that the USB setting would affect that, so I just assumed it was some odd quirk between macOS and the display!

I've now change the USB connection (in the monitor's settings) to 2.0. Simply doing that appears to have eliminated the distortion line!! Yahoo! Although it was still on 75 Hz in the macOS display settings, so that wasn't the issue. Something else about the USB 3.2 is problematic. I've since changed it to 100 Hz, and the line remains gone.

It seems the text might also be clearer now. Although I could be just be imagining that. But I found it seemed ever-so-slightly fuzzy before ... which I have simply gotten used to since buying it. Now it seems crisper.

Good point about the cable. In my case, I'm using the USB cable that came with the monitor. It's the fattest USB cable I've seen. Hopefully Philips supplied a cable that's capable of doing what's required.

Thanks so much for chiming in. Your input has resolved this problem. Your post also got me looking into on the monitor online, and I found this article, which is super informative.

So I now just have to accept I won't be able to use fast USB 3.2 peripherals if I want the display to look right. Oh well, I can think of worse problems to be dealing with.

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Answer 6

Branta_uk

Level 7

32,666 points

Mar 7, 2023 2:58 PM in response to InspiredLife

That is a potentially useful photo. I note your comment that the problem does not seem to show in software screen captures, only visible in the on-screen rendered image. I assume the posted picture is a camera image of the screen.

Looking at your photo I can see problems all over with shadowing and aliasing in many of the characters. That suggests two possible causes;

(a) Echoing and signal reflections in the USB-C cable because the cable bandwidth is insufficient or there is an impedance mismatch. It would not surprise me if this kind of problem becomes more or less visible with different devices at each end of the cable, which would be consistent with your comment that it was OK on a Mini M1

(b) Possibly a non-integer relationship between pixels in the driver device and pixels in the display. For example, if you try to expand a 2000 pixel image onto a 3000 pixel display, each original pixel becomes 1.5 pixels wide - but you can't have half a pixel any more than you can have half an atom.

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Answer 7

InspiredLife Author

Level 1

63 points

Mar 7, 2023 3:04 PM in response to InspiredLife

PS. The text is for sure much clearer now with USB 2.0. I've switched back to 3.2 to compare, and it's back to the lack of clarity (especially in type) I'd reluctantly gotten accustomed to. It seems ridiculous to me that Philips designed a monitor that is USB 3.2 capable (with a 3.2 capable USB hub etc.), yet the display quality (the primary function of the device) degrades so significantly when using 3.2 it renders it kind of pointless. What were they thinking?

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Answer 8

InspiredLife Author

Level 1

63 points

Mar 7, 2023 4:03 PM in response to InspiredLife

It's also worth noting, the Mac Mini is connecting via HDMI.

The monitor has a KVM feature, so both devices are connected to it simultaneously. One over USB-C and the other over HDMI.

When I connect the the MacBook Air to the display via HDMI (via an USB to HDMI adapter), I note that it only allows for a 30 Hz refresh rate, and the 1 pixel distortion line doesn't occur.

When I connect the Mac Mini M1 via USB-C the 1 pixel distortion line occurs on USB 3.2 and not on 2.0 (same as the MBA).

So it appears to be cable or display related, as opposed to the device attached.

I'm wondering if this is something I should bring up with Philips, as a potential fault?

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Answer 9

Branta_uk

Level 7

32,666 points

Mar 7, 2023 3:01 PM in response to Branta_uk

Talking to myself here - glad to see you found a partial solution even if the USB speeds are not ideal. At least it proves there is not a serious hardware failure.

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1 pixel verticle distortion line in middle of external monitor

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