Samsung U28D590 4K Display: Blurry, chromatic edges. No HiDPi mode.

Being so in love with the Retina Display on my 13 inch MacBook Pro Retina Late 2013 (16 GB RAM, 512 MB SSD), I just purchased the new low-cost Samsung U28D590 display. It has a TN panel, so the color accuracy is mediocre when it comes to viewing angles, but I was expecting that. Also the 30 Hz doesn't come by surprise, although I was hoping for more (it is connected HDMi Port Mac -> HDMi Port display). I'm aware that the GPU in the MBPr probably hasn't enough steam to do more (compared to the more powerful GPU in the 15 inch MBPr).


There are two things however which really bug me, and which makes me consider getting rid of the display:


1. No HiDPi


Despite running 10.9.3, there is no HiDPi mode. I also tried it with closed lid on the MBPr, but nada. 3,840 x 2,160 just renders the GUI a bit too tiny to fell comfortable. This is all I get („Niedrige Auflösung“ is german for „low resolution“; I can get more resolutions to choose from by pressing the option key when clicking on "Scaled", yet none of them are HiDPi).


User uploaded file


It would be interesting to know whether this is a limition in Software (namely Mavericks) or caused by GPU limitations. Ideas?


2. Chromatic halo (aberration) around text (and some graphics, too)


The rendered content (text and certain graphics) has a nasty reddish or blue halo. When viewed on the MBPr internal display it looks fine, when moved to the Samsung U28D590 it immediately becomes colorful blurry and annoying. See here (ignore the different pixels per inch, just look at the halo):


User uploaded file


Click image for full resolution. I made a photo rather than a screenshot to better show the annoyance.


Disabling LCD Font Smoothing in the System Preferences are not a viable solution to me, as I'm then back to jaggies rather than razor-sharp, super-smooth text. I also tried the "defaults -currentHost write -globalDomain AppleFontSmoothing -int 1/2/3" trick, but that did not improve the situation either.


I remember that long time ago, Mac OS X had the option to adjust the red/blue halo/shift in the Font Smoothing/Anti-Aliasing, which could be handy here.


The next thing I'll try is the procedure described in here (force RGB mode), although I'm not sure whether it describes my problem or not. Other than that, I'm clueless. Keep in mind that the text shown is really tiny at 4K on 28", which makes the halo really annoying.


Any ideas?


Sidenote: Like most Korean displays, the U28D590 has a silly sharpness setting (IMHO 1 pixel should be 1 pixel. Boom. No image altering sharpness adjustment needed), however it is set to the default value of 60 and changing it, does not remove the chromatic halo, but only makes the image more blurry or ridiculously sharp.

MacBook Pro with Retina display, OS X Mavericks (10.9.3), Late 2013, 2.6 GHz i5, 16/512 GB

Posted on May 21, 2014 10:04 AM

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26 replies

May 21, 2014 11:12 AM in response to Andre Klein

Tried the "force RGB" hack, but I'm no expert on this, don't have the time to read the entire thread and am not sure whether this is able to solve the problem or work under Mavericks at all. So it didn't work.


Regarding the HiDPi complaint: it should be noted that switching to a resolution other than 3,840 x 2,160 or 1,920 x 1,080 results in a scaled, blurry image, so definitely not HiDPi mode.

May 23, 2014 5:06 PM in response to Andre Klein

Hmmm. I had a bit different experience than yours. I have the exact same monitor, a late 2013 MBP, with the same specs, and 10.9.3.


I definitely do get hiDPI support on the Samsung monitor, with 10.9.3. With 10.9.2, I could only run it in normal resolutions (but admittedly all the way up to 3840x2160). 10.9.3 also offers a color management profile for the monitor, which dramatically improves the default color fidelity.


However, with 10.9.3, I can only drive one external monitor when the Samsung U28D590 is one of them. Given that I live for multiple monitors, this means that I deeply regret installing the 10.9.3 upgrade. If I had been smart and made a backup, I would have reverted to 10.9.2 in a flash!


I am hopeful this will be fixed in the next dot release. Until then, this fancy Samsung monitor is a $700 paper weight for me at home. I'm looking forward to loaning it out. So from my POV, the "improved 4K support" is actually worse.

May 26, 2014 3:31 AM in response to Thomas Phinney

As I wrote initially, disabling LCD Font Smoothing in the System Preferences are not a viable solution to me, as there is a noticable jagginess without Anti-Aliasing, despite the higher resolution of the 4K/Retina display. Furthermore "LCD Font Smoothing" affects unfortunately all displays, it can't be adjusted for each display individually.


How did you connect the Samsung U28D590? HDMI-HDMI cable? Or MiniDP to DP cable? I didn't have the latter at hand, so could only could use HDMI-to-HDMI. I've sold the display meanwhile, and while the buyer is still waiting for the MiniDP-to-DP cable for his Mac Pro to be delivered, he said that he had a pixel perfect image when he connected it via DP to his PC.


Anyhow, I've filed a bug report as Apple Developer, and it seems to be know as bug. I for my part will wait for a reasonably priced IPS or IGZO panel, as the color accuracy of Samsung’s TN panel was anything but satifying.

May 26, 2014 3:55 AM in response to Andre Klein

More details on 4K support: http://support.apple.com/kb/HT6008


Interesting though that the U28D590 isn't listed. I was looking for an SST/MST switch in the U28D590’s on-screen menu, but couldn't find such. Neither was I able to find any info on firmware updates for that display.


The article also mentions "MacBook Pro (Retina, Late 2013)" being capable of 4K@60Hz, however I'm still asking myself whether this includes the 13" MBPr Late 2013.

Jun 16, 2014 2:02 PM in response to Andre Klein

> disabling LCD Font Smoothing in the System Preferences are not a viable solution to me, as there is a noticable jagginess without Anti-Aliasing


Those are two different things.


The "chromatic text edges" are literally synonymous with "LCD Font Smoothing," which is Apple's equivalent of Microsoft's ClearType.


Turning off "LCD Font Smoothing" turns off the LCD-specific version of the smoothing, a.k.a. color anti-aliasing. It does not turn off anti-aliasing in general.

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Samsung U28D590 4K Display: Blurry, chromatic edges. No HiDPi mode.

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