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    My XPS 13’s display is also affected by this page, and I have a guess for the cause.

    LCDs have to constantly invert the polarity of the drive signal, and they way they avoid visible flicker when doing this is to alternate the phase across columns. This causes weird effects with patterns that have alternating bright and dark columns such that all the bright columns are driven on the same phase.

    I’ve seen similar patterns make LCDs flicker before, but apparently it can also cause cross-talk that produces ghosting outside the pattern. The “Crosstalk 2” pattern there also causes ghosting on my display.

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      What model year is your Dell XPS 13 from? I wasn’t able to see any weirdness on my 2017 model.

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        2019 (model 7390). I have the 1080p display. If you have the 4k, make sure it’s displaying at the native resolution so the pixels alternate between red and black. Any scaling will avoid triggering this effect.

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      I love the idea of creating a simple html page that tests a visual bug. Very cool.

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        That’s odd. I have the same phenomenon, but much fainter - barely visible - on my ASUS PB248Q IPS Screen. My Thinkpad T450s has no such artifacts. I ruled out optical illusions by taking a photo and just looking at the black part.

        Here, see for yourself: https://imgur.com/a/mMR2xCR

        The effect is very subtle and in person, it looks like the bar to the left of the red bar has a different reflectivity than the rest of the grey. But maybe what I’m seeing is completely unrelated to OP’s phenomenon.

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          Same issue on my Dell Ultrasharp U2515H FHD IPS external monitor, although a bit more visible than in your photo (but considerably less than in OP’s photo). Also it only shows if the left-hand grey area takes up between 40-60% of the screen.

          Photo: https://imgur.com/a/nIaUZz2

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          I literally received my new ThinkPad T495 like half an hour ago, installed Linux on it, opened lobste.rs to check internet connection and saw this.

          And yes, it’s happening to me as well.

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            Also the case on my x395 with IPS 1080p non-touch non-privacyfilter screen.

            On Linux.

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              No problems here on the Lenovo E585 (Windows), Thinkpad Carbon X1 3rd Gen (Windows) and Thinkpad T480s (Linux) I have to hand.</smugmode>

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                Have you checked the inversion pattern test pages mentioned in kevinmehall’s comment? http://www.techmind.org/lcd/#inversion (epilepsy warning on subpages)

                I have a Thinkpad T520, and while OP’s page doesn’t show anything, I get flicker for these test pages:

                • Line-paired pixel dot-inversion (160,160,160)-(0,0,0)
                • Line-paired RGB subpixel dot-inversion (160,0,160)-(0,160,0)
                • Line-paired dot-inversion (green) (0,160,0)-(0,0,0)

                …with the middle one being the worst.

                ETA: My T430s doesn’t have an inversion pattern matching any of those, interestingly. Same for my T420, although that one shows some faint “crawlies” on a few of the dot inversion and paired row-inversion pages.

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                  Yep, got some flicker there…and it didn’t trigger my epilepsy…..fffzzzttttt NO CARRIER :)

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                My old X series tablet used to do this and various other ghosting. I think it was an X270T.

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                  My current Thinkpad X1 5th gen is not affected by the way.

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                  I have an external screen that has a similar issue, but it’s even worse: when I have too much of a certain color on screen, the screen shuts down and has to be powered off for quite a while (an hour?) before it starts working again.

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                    That’s interesting! How close can you get to that colour? Does it have to be exact?

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                      Due to the effects I haven’t experimented a lot, unfortunately!

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                        Once you get tired of that monitor, you’ll have to sacrifice it for science. Lots of cool questions for something that breaks in such a funky way.

                        e.g. Does it work if you pull the power cord and plug it back in? Is the monitor getting kinda old and maybe has dying components inside?

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                          Pulling the power cord didn’t help, IIRC. Something likely overheated, since it came back to life after a while. This happened when the screen was fairly new, and I’ve had it for a few years after the incident so it’s probably some bug and not faulty components 😊

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                            Bad solder joint somewhere in the driver circuit for that colour?

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                    I don’t see this on my iPad

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                      I suspect that has to do with scaling.

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                      No problems on a T42p (1600x1200 S-IPS)

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                        I’m getting this as well on my 1440p 27” benq monitor

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                          i remember having a very simliar type of situation on a dell inspiron way back in 2006. i even made a gif of it at the time to recreate the illusion http://users.content.ytmnd.com/5/3/0/53038c639ae01c8d21b9bbda0dc4a181.gif , although it was more faint than the example on this thinkpad demo (which affects my screen too)