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Retina on the PC

I talk about my new monitor
by Sunny Kalsi on Jan. 15, 2014, 10:39 p.m.

One thing that might be surprising is that in books it is unusual to see a font above 10pt for regular type. Most books are at 8pt, “large” type is usually at 9pt, and very rarely you’ll see text at 10pt. Headings can be 12 or 14pt. By contrast, displays regularly use 16pt for regular type, and 24 or even 48pt for headings. Part of the reason is that our eyes are typically further away when reading from screens compared to books.

But that’s not the only reason. Screens, modern LCD screens in particular, have an awful pixel density, also known as PPI (pixels per inch). This is partly due to the fact that modern LCDs have a fixed matrix of dots, and you “pay” for each one, unlike CRTs which have a single cathode ray which can be made to go pretty much anywhere on the screen. Partly, though, this is driven by consumer demand, and “bigger is better” also means that we’ve been paying for screens that have been increasingly blurry.

Font rendering on this kind of screen is awful, to the extent that rendering 8 point text is extremely difficult to read, and even 10pt text can be a struggle. Even for a PPI-conscious user, the best monitors which are still on the market would only reach 100PPI. Contrast that with a printer which renders at 600DPI (dots per inch). The font rendering problem is also exacerbated on LCD displays because they tend to have sharp pixel edges compared to CRTs which tend to have “blurry” edges that do extra signal processing for us for free.

The math is actually rather shocking. When you look at Shannon’s law and how small pixels need to be to be pleasant to read at “book” sizes, you need close to double the resolution that monitors are commonly at today. Another convention which has come about recently is a Retina screen, more correctly a retina threshold in this context, one where a particular pixel density at a particular minimum distance would mean that Shannon’s limit matches our eyes. A 1080P monitor that’s merely 21” would have to be 84 centimeters away from you to be “retina”. At a more comfortable 45cm distance, you would need roughly 200PPI.

The only monitor to have that pixel density was the IBM T220/221 and it was discontinued several years ago. This monitor has a cult following, to the extent that it has held its value quite well for several years. There was simply no other way to get a monitor like this.

Until now. In November 2013 Dell launched the UP2414Q which, although not quite the same pixel density of the T221, is closer to matching it than any other PC monitor that I’ve been able to find. It also fills a magical enclave of numbers: it’s a 4K monitor, it’s 23.8”, which is ideal for a desktop monitor, and it manages a comparatively massive pixel density of 185PPI. It’s also an IPS display with 100% sRGB coverage, factory calibrated.

While some have the attitude that this sort of monitor will somehow become massively cheaper, I’ve been desperate enough for this for long enough, and the price was suitably low for me to take the plunge and buy one. In my book, people still see bigger as better, and may not see the value of paying more for a 24” monitor compared to a 27” monitor, so odds are about even that even this monitor will become a relic with a cult following, like the IBM T221.

So how does it look? What are the caveats? Does it work on Linux? Was it worth it? Do (Linux) apps even look proper on it? I’ll try and tackle these questions presently.

Looks

How does it look? The answer is “good”. It’s 185PPI, so it just sits on the brink of being retina at a comfortable PC viewing distance. Not one to buy factory-cal monitors, the colour accuracy is something I’m not used to, and it’s really quite nice. The problem is, we’ve been fairly spoilt with tablet and phone displays, and this monitor looks like a phone display from 5 years ago. If you’ve seen the 15” retina macbook pro display, the colours look like that, though the pixel density is slightly (but noticeably) worse. The original Nexus 7 is probably also a good comparison for screen quality.

It’s also much, much larger than a retina macbook or a Nexus 7.

Hardware Caveats and Notes

One of the biggest caveats with this (or any) 4K display is how you drive the thing. HDMI and DVI won’t work, they’re only good for a refresh rate of 30Hz. Before you think “it’s OK I won’t be doing any gaming” it’s really not OK. 30Hz feels… wrong. Your mouse feels drunk and the screen updates slowly when you drag windows and you won’t be able to do your work.

Because HDMI won’t work, you need display port, but not all video cards can even drive 4K, and not all of them can drive it at 60Hz. For Nvidia, you need a Kepler based card. AMD fares slightly better, but check! You also need DisplayPort 1.2. DP 1.1a won’t be enough. Again, this is something to check.

DisplayPort 1.2 can only do 60Hz refresh under what is known as MST (Multi Stream Transport) mode. What’s happening is that DisplayPort is just a multiplexed HDMI stream (roughly), which isn’t capable of pushing out 60Hz. To work around this, the monitor pretends to be two screens: the left half and the right half, driven by two HDMI-ish streams. This means that not only does your video card need to support this mode, your driver needs to as well. Apparently this will be fixed with DP 1.3 and HDMI 2.0, but for the Dell UP2414Q, this will be an unfortunate reality for me, forever.

I had my fair share of driver issues on my Linux box, and it appears that Windows also has those same issues, but manifested in a different form. Most notably, coming back from suspend will sometimes work and sometimes not. I have to switch the monitor off and on again (same as with Windows, apparently). There are also strange screen tearing issues between the two displays, and gaming is apparently not an option.

While I’m talking about monitor caveats, here’s another thing to remember: Because most OSes are used to the very low DPI monitors, they do various acrobatics to make small fonts readable, notably font hinting and sub-pixel rendering. At high DPI, this actually makes things look worse. Be sure to switch both of these “features” off. Do keep Anti Aliasing, though.

Software Caveats and Notes

If you have multiple monitors, the other monitor’s PPI will be completely different. This causes a number of issues no matter your situation. If you’re using Win7 or Linux (with spanning display) you have a fixed PPI across all your monitors. This will mean your low-PPI monitor will be “zoomed in” by a factor of roughly two. This is just crazy. All the elements are just comically large. Even a 1080P screen is a quarter of the pixels of a 4K screen, so the extra “screen” real-estate you get with a fixed PPI is negligible.

If you have separate PPIs like Windows 8 or Linux (with separated display), the low-PPI display will be blurry. With a higher PPI, it becomes much more comfortable to read text at a smaller size. If you take advantage of the smaller size, but then move that window to the low-PPI display, it will become completely unreadable. 8 pt font goes from being comfortable to being an impressionistic painting. This is pretty frustrating.

If you have two 4K displays, god help you. Whether hardware can even drive dual DP1.2 displays is beyond me, but it needs to be a crazy good video card. Then there are potentially various software and hardware bugs that only you are there to find. Finally, you would be better off waiting until 2015 when DP 1.3 comes out and there’s a single “link” to 4K.

How does the software look?

One of the good parts is that while Linux has various issues with the scaling, it generally deals with it better than Windows. In a similar way to how Windows programs each deal with scaling in esoteric ways, Linux will have DPI settings split across many different dimensions.

First is the X display setting for PPI, which some programs use, and others don’t, because it’s “unreliable”. Then, Gnome and KDE each have a “scaling” value, which they use to re-scale their UI elements. Firefox also has one. Finally, some programs will use pixels directly. Luckily, these are all configurable, and once you set them they will generally not need to be changed.

Firefox renders the web well at the high DPI setting. Strangely, some of the icons on the UI will be blurry, even if they’re SVG (the webpages themselves will be fine though). Hopefully the GTK3 build of Firefox will fix that issue. GTK mostly deals with the scaling perfectly. I had a strange issue with Nautilus not scaling, but with all the Gnome UI elements being gigantic, 4K actually fixes them up somewhat.

One thing I was surprised at is how much our hind-brain thinks about the screen as a grid of pixels though. When all of the elements are scaled but still crisp, your brain feels a bit lost. Things still line up, but because of the crispness, your brain doesn’t “sense” that they’re on the same pixel line, and you think something is wrong when it isn’t. The location of your mouse is also a lot more fluid, and the acceleration values are different (because they’re based off pixels), so it confuses movement.

Overall, though, it looks great, especially for text-oriented apps like gvim. Writing on this thing is gorgeous. The text is sharp — the contrast and weight looks far more natural, especially on italic and bold text. Serif fonts actually look better on the monitor than Sans (although both look better than on a ye olde monitor). Reading on this thing is also great. Pictures look much the same, but certain moire effects and aliasing are definitely noticeably lower. To some extent, this isn’t revelatory, because we’re used to this kind of detail from phones and tablets. However, it’s the sheer size of this thing that’s awesome. This display is 8 Megapixels, which is the same as a Canon 350D or a Galaxy S3. You can look at a picture taken on a Canon 350D without scaling (it’s slightly too tall, but also slightly too narrow). That’s pretty special.

So, that’s what it’s like owning a retina 4K monitor. It’s not perfect, but it is kind of special.

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