Blurry Text with External Display via MacBook Pro

Discussion in 'Mac Basics and Help' started by OhPleaseHelp, Dec 13, 2018.

  1. OhPleaseHelp macrumors newbie

    Dec 13, 2018
    Hey guys,

    I have a 15" Retina MacBook Pro mid 2015. I've just picked up a Dell SE2419H 1080p monitor to use as a second screen for work.

    When plugging in via HDMI or DisplayPort>HDMI the fonts look very blurry and colours are a little off. I've done a lot of searching and trying different things over the last few days to try to fix it.

    I first read that MacOS thinks my monitor is a TV rather than a Monitor so I would need to edit the EMID Overrides using this guide: force-rgb-mode-in-mac-os-x-to-fix-the-picture-quality-of-an-external-monitor
    It did make a difference and the resolutions I was offered in Preferences changes from 1080p to 1920x1080 - so I guess my Mac now recognises this is a Monitor. However the fonts are still very fuzzy and unsharp.

    I've also read that the the external display isn't using HIDPI and that's what's causing the issue, so I'm using SwitchResX to change to a HIDPI resolution, which does make the fonts look great however there isn't a HIDPI resolution available in the list that I can select that correctly fits my screen. 1280x800 HIDPI is the closest but still not there. I expect I'd either need 1920x1080 HIDPI or 960x540 HIDPI to resolve.

    As I can't select these resolutions I've read they needed to be added as custom resolutions in SwitchResX, but when I add them and press Install the screen brings up the Apple symbol, loads but never actually installs them.

    I've also tried using the guide at to add custom resolutions, but they just don't appear in the list no matter what I try.

    Can anyone offer me any suggestions that might help resolve the issue? I'm getting desperate at this point, I'm happy to return the display for another one but my concern is I'll have this with any 1080p monitor I pick up.

    Any help would be massively appreciated.
  2. Fishrrman macrumors G5


    Feb 20, 2009
    I looked at the specs for that display, and it seems to have only HDMI and VGA inputs.

    Normally, I would suggest using a USB-c (mac end) to displayport (display end), but you can't do that.

    Something important to be aware of -- compared to the retina display of the MacBook Pro, a 1080p display -might- appear "grainy" to the user. What this really depends upon is the individual user's quality of vision. If you're younger with near-perfect vision, your eyesight may be keen enough to notice these distinctions. I'm older with weakening vision, so a 1080p resolution on a 27" display looks "good enough" to me.

    If you want "the blurriness" to DISAPPEAR, get yourself a 4k display.
    The image will look MUCH better.
    They cost more than a 1080p display (of course). But the "cost differential" really isn't that much and you'll probably like the display quality MUCH more.
  3. OhPleaseHelp thread starter macrumors newbie

    Dec 13, 2018
    Thanks, but the issue isn't because it's not a 4k display, if I change the settings to a HIDPI resolution the text becomes clear and edges look good and rounded, not 4k good but still good enough for what I need. However none of the resolutions that are HIDPI fit my screen correctly.
  4. mkelly, Dec 13, 2018
    Last edited: Dec 13, 2018

    mkelly macrumors regular

    Nov 29, 2007
    1920 x 1080 isn't capable of HiDPI at its native resolution. If you do the math, a 23.8" diagonal monitor, at 1920x1080, has approximately 92 pixels per inch. This is a physical limit of the display. You can't get that monitor to support a HiDPI resolution at 1920x1080 because there just aren't enough pixels to do it.

    Now as you said, you can drop the screen resolution to 960x540, which would enable you to run the monitor in HiDPI - however 960x540 is going to give you an incredibly small amount of screen real estate (icons, windows, text, etc are going to be huge relative to the size of the monitor).

    Fishrrman is most likely correct: you are used to your Mac's built-in display, which has a high native resolution (2880 x 1800, or about 220 pixels per inch). Because of the higher pixel density, macOS can render a 1440x900 screen at twice the sharpness. Same thing goes for 4K monitors: their native resolution is 3840x2160 - but macOS will default to displaying content at an effective 1920x1080 size, and uses the extra pixels to increase sharpness.

    You are dealing with physical constraints here. If you want a 1920x1080 image that is as sharp as your MacBook Pro's internal display, the only solution is to get a 4K monitor. Otherwise, your options are:

    1. Live with 1920x1080 at 92 pixels per inch, like we did in the dark ages of pre-Retina/HiDPI displays (this will be the case with all 1920x1080 monitors, as you surmised), or

    2. Lower your resolution significantly so you can use a HiDPI-capable res, but lose a whole lot of screen real estate as a trade-off.

    Re: #2 - In terms of finding the right HiDPI resolution, I can't say. You may want to drop a line to the SwitchResX developer and see if they have any suggestions as to making your custom resolutions "stick". But I'd really avoid that route - you're going to lose so much screen real estate it won't be worth it. Better to return the display and save up for a 4K. There have been some *very* good sales lately this season.

    BTW: The resolution of a 1080p display is 1920x1080 - which is why doing the EDID overrides didn't result in any better picture quality. They can help if the monitor is using the wrong colour space, but it doesn't sound as though that was the case here.

    If you have a decent camera handy, take a shot of the external display and post it here. We'll be able to tell you pretty quickly whether it's a "normal" 92 ppi display, or if there's something else wonky going on.
  5. OhPleaseHelp thread starter macrumors newbie

    Dec 13, 2018
    So I swapped out my HDMI cable for a VGA cable and wow what a difference, sharp text like proper 1080p. Colours are better too, no idea why HDMI made everything look crap.
  6. Fishrrman macrumors G5


    Feb 20, 2009
    "So I swapped out my HDMI cable for a VGA cable"

    Good move.
    When "one way" doesn't work, but "another way" does...
    Use "the way that works".

    It's really that simple...

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