27" iMac achieving 1920x1080 Pseudo HiDPI mode

Discussion in 'iMac' started by jediDev, Jan 29, 2013.

  1. jediDev macrumors regular

    Jun 13, 2012
    I know you can 1280x720 HiDPI mode on the 2560x1440 27" iMac display simply by enabling HiDPI mode—but what I want to do is is get a higher-quality 1920x1080 scaling enabled.

    I haven't seen or heard of anyone being able to do this, but I'm sure there must be a way to accomplish it.

    For example, I do know that when I hook up my MBPr and choose display mirroring, the display ends up showing a HiDPI version of of a 1440x900 or 1680x1050 or 1920x1200 display. So clearly the 27" iMac (and in fact any 1440p display) is capable of handling Retina-like scaling.

    Now, I know this wouldn't be true retina, because you'd still be closer to the display. But for my purposes, it would be the ideal resolution. I'm sure there is a worthwhile debate about whether or not this is desirable, but I'm not interested in debating that—what I'm interested in knowing is if anyone has either accomplished this or has any ideas of things to try.

    Obviously I'll report back if I figure it out.
  2. Fried Chicken macrumors 6502

    Fried Chicken

    Jun 11, 2011
    This would be great for people with seeing problems.

    Also, screenshots would be cool.
  3. jediDev thread starter macrumors regular

    Jun 13, 2012
    Yeah, it would allow certain parts of the ui to get larger while other parts could remain small. My particular use case is probably kind of abnormal, but while I'm sure it's technically possible to accomplish this, I have no clue how to do it. The 1920x1200 mode is semi-acceptable, but it only works when i am connected via my MBPr and have display mirroring turned on, which is kind of a waste.
  4. Stetrain macrumors 68040

    Feb 6, 2009
    There's a way to enable the HiDPI modes on non-retina Macs:


    (There's a second post further down that shows how to do it without downloading Quartz Debug)

    Not sure if 1920x1080 HiDPI will show up on an iMac but it's worth a shot. Also remember that in this mode your computer will be rendering 3840x2160 pixels and then downscaling, so it may have a performance hit.
  5. jediDev thread starter macrumors regular

    Jun 13, 2012
    I'm aware of that, but that only allows a resolution that is 50% (or less) of the display--i.e., 1440p becomes 720p. What I'm looking for is something like what the MBPr can do with scaled resolutions. The default setting let's 1800p run as 900p, but you can scale it to be 1200p running on 1800p.

    The 1440p monitor can display 1920x1200 hidpi mode, but only when mirroring is enabled from a connected MBPr. And when it does that there's black bars on the side because it's 16:10.
  6. Stetrain macrumors 68040

    Feb 6, 2009
    Have you tried QuickRes? http://www.quickresapp.com/

    For me it shows a HiDPI option (960x540) that my Macbook normally doesn't show.
  7. jediDev thread starter macrumors regular

    Jun 13, 2012
    What size MBP are you using?


    It seems to just show the standard HiDPI modes. Thanks for the suggestion though.
  8. Stetrain macrumors 68040

    Feb 6, 2009
    13" MBP, 1280x800. With the normal Quartz Debug mode I don't get any HiDPI resolutions. Quickres lets me set 960x540 HiDPI as well as 1920x1080 non-HiDPI, both of which normally don't show.

    SetResX lets you set custom resolutions, but I don't think it lets you set a custom HiDPI mode.
  9. jediDev thread starter macrumors regular

    Jun 13, 2012
    Quick Res does expose a few more non-HDPI resolutions than are visible by default (including 1920x1080) but it's max HDPI resolution is 720p.

    I'm thinking that what needs to happen would be to somehow convince OS X that the 27 inch display is a retina laptop display with a new resolution. But odds are they've hardwired these into the OS. If you can assign it arbitrarily however, maybe it would be possible to end up with the "best for retina display" and "more space" type options.
  10. Chinaski73 macrumors newbie

    Mar 19, 2013
    Hey jediDev, just ran into this thread, wanted to check to see if you found a way to get 1920x1080 HiDPI on the 27 iMac
  11. jediDev thread starter macrumors regular

    Jun 13, 2012
  12. jediDev thread starter macrumors regular

    Jun 13, 2012
    Wow, SwitchResX "just worked" — no configuration needed. (I'm going from a mid-2012 base rMBP to a Thunderbolt display.
  13. blanka macrumors 68000

    Jul 30, 2012
    Apple designed OSX 10.0 already to be scalable in every DPI you like. Somehow they did not bother to actually use the built in core functionality. Even today's retina screens are working with a crippled implementation of this.
  14. jediDev thread starter macrumors regular

    Jun 13, 2012
    IIRC the problem was that the approach it took to resolution independence didn't actually work when factoring in reliability and/or efficiency. But a truly resolution independent graphical interface would be terrific.

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