In my Mac Pro review I lamented the state of 4K display support under OS X 10.9.0. In my conclusion I wrote: "4K display compatibility under OS X is still a bit like the wild west at this point". Compatibility was pretty much only guaranteed with the ASUS/Sharp 4K displays if you cared about having a refresh rate higher than 30Hz. Even if you had the right monitor, the only really usable resolution was 3840 x 2160 - which ends up making text and UI elements a bit too small for some users. Absent were the wonderful scaling resolutions that Apple introduced with its MacBook Pro with Retina Display. Well it looks like that won't be the case for long, last night I got reports (thanks Mike!) that the latest developer build of OS X 10.9.3 includes expanded support for 4K displays, 4K/60Hz support for rMBPs and scaled resolutions below 4K.

For starters, the list of compatible displays in 10.9.3 extends beyond the ASUS/Sharp models. The 32" and 24" Dell 4K panels are now supported, and I'm guessing the < $1K 28" 4K monitors should be supported as well. You could drive any of those panels prior to 10.9.3 but not at 60Hz. 

The display preference pane now includes support for scaled resolutions just like on the rMBPs. The default in 10.9.3 is still the panel's native resolution, but you now have the option to choose 3200 x 1800, 2560 x 1440, 1920 x 1080 or 1280 x 720. All of these options are treated the same way that the rMBP's scaled resolutions are handled. In the case of the 2560 x 1440 setting, your display is rendered at 5120 x 2880 with text/UI elements drawn at 4x the size (2x in each dimension) and images/video in supported applications drawn at 1x size (1:1 pixel mapping). Once the frame is built, it's scaled down to fit the panel's 3840 x 2160 resolution - giving you a fairly sharp image. I suspect Apple is using their own filtering algorithms here as well in order to ensure maximum quality for the downscaled image.

The beauty of Apple's scaled approach is you get totally usable text/UI elements while still getting all of the benefits of having tons of screen real estate for working on images or videos. The example below features a Photoshop CS6 window with a blue box measuring 3000 x 1500 pixels with no scaling (viewport is set to 100% scale). In this particular example the display is running at the 2560 x 1440 scaled setting, but as you can see the 3000 x 1500 image can still fit on the screen without scaling or scrolling. This is only possible because the off-screen desktop resolution is a whopping 5120 x 2880 and image elements are rendered 1:1:

You'll also notice that despite the ultra high off-screen resolution, all text/UI elements appear as if they were drawn on a 2560 x 1440 display. That's the 4x scaling at work.

Prior to 10.9.3, you could force some lower-than-native resolutions on 4K panels but you'd get a lower res desktop upscaled to fit the panel, without any of the HiDPI benefits I just outlined.

There may be a performance impact to the scaled resolution settings (the 3200 x 1800 option actually draws your screen at 6400 x 3600), particularly if you're driving a 4K panel off of an rMBP but I suspect any of the beefier Mac Pro configurations should be fine. This is definitely something to look at once 10.9.3 goes final. 

This is a huge step forward in improving the state of 4K under OS X. The 10.9.3 update is a smaller update than 10.9.2 (~200MB vs nearly 800MB), which took around two months from initial seeding to final release. 

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  • andy5174 - Saturday, March 8, 2014 - link

    Are you planning to do rMBP late 2013 review?
  • solipsism - Saturday, March 8, 2014 - link

    I'm surprised they didn't consider many of the changes, but if they haven't at this point I wouldn't expect them to now.
  • Zandros - Saturday, March 8, 2014 - link

    Sure, a bit earlier would have been ideal, but I come here for technical details, not speed. So I would still read it, and isn't that what counts, really?

    Actually, I wouldn't mind waiting until after 10.9.3 to get a proper idea of how 4k displays work with the 2013 13" rMBP.
  • solipsism - Saturday, March 8, 2014 - link

    1) I agree, but historically they tend to release their in-depth reviews within a month, not six months.

    2) I also agree with this, but as a mini-review of the 4K results of various displays across the Late 2013 MBP and Mac Pro.
  • andy5174 - Saturday, March 8, 2014 - link

    I have no choice but wait for windows NINE laptop release then...
  • KPOM - Monday, March 10, 2014 - link

    Check the Mac Pro review for some benchmarks that include the 2013 rMBP 15" model. I agree it would have been nice to get a "full" review of the 13" and 15" models, including how the HD5100 and Iris Pro fared, and what battery life was.
  • SignalPST - Monday, March 10, 2014 - link

    I've been waiting for the late 2013 rMBP review as well. Last time I checked, Anand said he was doing a combine article with the Mac Pro...
  • solipsism - Saturday, March 8, 2014 - link

    I assume it will take a good 2 months for 10.9.3 to be released to all Maverick users. That puts us just before the usual time for WWDC. I also think that WWDC is a great time to introduce an expensive, professional Apple 4K (or UHD) display with a TB2 hub supporting GigE (I think 10GigE is unlikely… ever), ≥3xUSB3.0, HD FaceTime camera, microphone, speakers, additional TB2 port. MagSafe and Kensignton lock, too (the latter of which is oddly missing from the new MBPs). I would expect FW800 to go away and expect it to match the new iMac design.

    I would be surprised if it's under $2k, and likely coming in at $2,999, if not more.
  • esterhasz - Saturday, March 8, 2014 - link

    I think (hope?) that they'll keep an option closer to $1000 - external screens are something that you'd get with a Mac Mini or Macbook purchase and anything above $1200 or $1300 becomes really hard to justify for a lot of people. I love having an external screen and I'd definitely buy a 24" model like the Dell one with real estate equivalent to 19x12 or 19x10 for $1000. Super sharp text for coding and I like to sit close to the screen, so 27" is too big. But man, at the price range you're quoting only 2D/3D/video artists are going to buy.
  • MartinT - Saturday, March 8, 2014 - link

    So, basically images and video are permanently scaled (err, broken), even when using the panels native resolution? Why would you do that?

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