Screen Resolution

Discussion in 'iMac' started by Robert4, Apr 19, 2018.

  1. Robert4 macrumors 6502

    Joined:
    Apr 20, 2012
    #1
    Hello,

    Have a several month old iMac.
    Have been really impressed with the display, and have never played around with it.

    When doing a Search, using "Resolution," I see that there are a whole bunch
    of resolutions to pick from that have "Retina" next to it.
    e.g., 3840 x2160
    3360 x 1890

    It seems to be set now per a checkmark at 2048 x 1152

    I realize that personal preference is probably the controlling factor,
    but wasJust wondering: what do you folks use ? Why ?

    Thanks,
    Bob
     
  2. jerwin macrumors 68020

    Joined:
    Jun 13, 2015
    #2
    i use the default-- I sometimes force 5k resolution if the archive I'm using doesn't send a high enough resolution image of the text I'm interested in.
     
  3. CWallace macrumors 603

    CWallace

    Joined:
    Aug 17, 2007
    Location:
    Seattle, WA
    #3
    I always use "Default for display", which on my 27" 5K is HiDPI 2560x1440. I find the native 5120x2880 to render text and icons far too small.
     
  4. TyWahn macrumors 6502

    TyWahn

    Joined:
    Oct 25, 2003
    #4
    So if using the default instead of native resolution, it’s not true 4K? For example if I used Chrome and watched a 4K video it’s not really 4K?
     
  5. CWallace macrumors 603

    CWallace

    Joined:
    Aug 17, 2007
    Location:
    Seattle, WA
    #5
    On Retina displays, the recommended ("Default for display") resolution is one-half the native. So on a 4K iMac, this would be 2048 x 1152 (one half of the native 4096 × 2304). The advantage of this is that it makes text and other graphical elements easier to read and sharper.
     
  6. Samuelsan2001 macrumors 604

    Joined:
    Oct 24, 2013
    #6
    It is true 4k it’s scaled so that the elements are not too tiny to read.
     
  7. Robert4 thread starter macrumors 6502

    Joined:
    Apr 20, 2012
    #7
    Hi,

    Thanks for comments.

    I can't seem to find it now, but I know from my literally playing around with it, a screen sometimes comes up
    with the options to change the icon grid spacing, size, etc. Can't seem to get to it now.

    So, is it possible to use a (much) higher resolution than the "Default" for the display,
    yet to go in and change the icon size to something "bigger", as the higher resolution has now made them smaller ?

    Or, just something one has to live with when using higher resolutions ?

    Bob
     
  8. Anonymous Freak macrumors 603

    Anonymous Freak

    Joined:
    Dec 12, 2002
    Location:
    Cascadia
    #8
    The way "Retina" resolutions work in macOS is that any content that is aware that you're on a Retina display (which is most, nowadays,) will display high-resolution images at "native one-pixel-for-one" resolution. So if you're displaying on a 3840x2160 screen in any "Retina" or "HiDPI" setting, and you put a 4K YouTube video full screen, it will display the full 3840 pixels wide by 2160 pixels tall. Same with photo editing apps - they will display at the one-pixel-for-one native resolution of the screen.

    For apps that don't need one-for-one pixel accuracy (like text-based programs, or even the non-one-pixel-for-one sections of apps like Final Cut Pro, web browsers showing the text portion, etc,) it shows at an "effective size" based on your resolution setting (the "looks like",) but actually rendering the screen at higher than your screen's native resolution (generally by a factor of 2 if you're setting it to an "effective" resolution of half the native resolution or higher, or a factor of 3 if lower,) then downsampling it to the screen's native resolution using the GPU. So if you set your 4K screen to "looks like 1280x720", it will actually render at 3840x2160, three times the chosen resolution, it will just make everything 3x larger. Fonts will look super-crisp, any apps that are properly made with Retina in mind will have their interface elements 3x bigger, but smooth. Apps that aren't Retina aware will display big ugly interface elements. Notably, it took Google a while to update Google Chrome to be Retina-aware, and Chrome uses its own text renderer, so it looked like garbage on Retina displays until Google finally updated it. If you set your resolution to "looks like 2048 x 1152" (on a 3840x2160 display,) it will render it at 4096x2304, then use the GPU to downsample it to 3840x2160 so that it looks sharp.

    In systems with a couple-generation-old integrated GPU, and the earliest Retina-capable machines, you tend to see a slight performance hit if your "looks like" resolution isn't exactly half the actual native resolution because the GPU scaling takes a lot of effort that those older/integrated GPUs can barely handle. But modern GPUs can handle it with no problem.
     
  9. Robert4 thread starter macrumors 6502

    Joined:
    Apr 20, 2012
    #9
    Hi,

    Great explanation.
    Thanks.
    A lot clearer now.

    Bob
     

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