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"4K" is a format, a resolution, and a marketing term that implies a whole host of features. "4K" is also part of a new console war, the hottest thing in TVs, and the bane of your monthly internet data cap.
For a technology that’s all about sharpness and clarity, it sure can be muddy and confusing. Here, we’ll try to answer the most common 4K questions to give you a basic understanding of what it is, and what it means for gamers.
At its most basic, the term refers to a resolution of 3840 x 2160, which some call 2160p for short. You might be saying to yourself, “Hey, why is it called 4K when neither of those numbers are 4,000?” Well, the digital cinema resolution for movie theaters is just a touch wider: 4096 x 2160, and that’s where the term comes from. The resolution used in consumer devices is just a little less wide to conform to the 16:9 widescreen format we’re used to with high definition TVs.
Also, 4k is a nice, even multiple of “Full HD” resolution (1080p), too. 3840 x 2160 is exactly double 1920 x 1080 in both width and height. So for every pixel on a 1080p TV, there are four pixels on a 4K TV.
With four times as many pixels as 1080p, 4K brings out details you could never see before. (source: 4k.com)
“4K” has also become a marketing term that has come to mean a lot of things, depending on the company using it. It sometimes means resolutions less than 4K but greater than HD. Sometimes it includes HDR, or wide color. But when we’re talking about technology for the home, 4K generally means “a resolution of 3840 x 2160.”
The PS4 Pro and Xbox One X are both capable of running games at 3840 x 2160, and will always output that resolution to your 4K TV (even if the game runs at a lower resolution). The older PS4 and Xbox One S can’t run games at that resolution. The Xbox One S, however, can play video from Ultra HD Blu-ray discs and streaming services in 4K, and will output 4K to your 4K TV even if it’s playing a game (it just upscales the game from a much lower resolution).
HDR is short for High Dynamic Range. The dynamic range of an image is the difference between how bright the bright parts can be and how dark the dark parts can be without losing information. Without HDR, bright skies become a blown-out white blur, and dark shadows become inky black depths with no detail. With HDR, you can still see detail in the brightest and darkest areas of a scene, and colors no longer look washed out and dull.
You can’t really show HDR on an SDR display, but this dramatic simulated comparison gives you an idea of what the difference is like. (source: YouTube.com)
There are two HDR formats you need to know about: HDR10 and Dolby Vision. HDR10 is targeted at TVs that get as bright as 1,000 nits, and uses 10-bit color. Dolby Vision expands that to a maximum of 10,000 nits (way beyond the capabilities of any current TV!), with 12-bit color. Since current TVs can’t handle that, the Dolby Vision content you get today targets 4,000 nits of brightness and uses 10-bit color.
HDR10 is everywhere. It’s the standard that games consoles use for HDR games, and it’s supported by every HDR-capable 4K TV. Dolby Vision is sort of an “extra step up” that is only supported by some TVs and isn’t used by any games. You’ll only find it on some streaming video content and UHD Blu-ray discs. If you’re trying to play a movie that supports Dolby Vision and only have a TV capable of HDR10, you’ll still get HDR10, so don’t worry.
To make HDR content look its best, you want a display (a monitor or TV) that has high peak brightness and really good contrast. Both the Xbox One S and PS4 support HDR on select games, even though they don’t run games at 4K. The original Xbox One does not. The PS4 Pro and Xbox One X both support HDR as well, of course.
You know how some PS4 or Xbox One games actually render the graphics at less-than-1080p, but the console stretches it up to 1080p before passing it to your TV set? That’s upscaling. It’s taking a lower resolution image and blowing it up to a higher resolution.
Let’s say you have a PC with a 1080p monitor: 1920 x 1080 pixels. But that hot new game runs sort of choppy at that resolution, so you go into the settings and set it to 1600 x 900 to make it run faster. Well, it still displays across your entire monitor—that’s upscaling. The image is a little fuzzier, but it runs faster.
Modern consoles all automatically upscale content before sending it along to your TV. For example, the PS4 outputs everything at 1080p, even if the game is rendered at 900p like Star Wars: Battlefront. The PS4 Pro, Xbox One X, and Xbox One S all output 4K signals to a 4K TV, upscaling all content (games, video, whatever) from its native resolution to 3840 x 2160.
An upscaled image is fuzzier than one that is rendered at a native 4K resolution, but it lets the game run faster, which in turn lets developers make fancier graphics or maintain a higher frame rate. Lately, many games make use of what is called dynamic resolution, where the game’s native resolution moves up and down depending on how intense the action on the screen is. So a busy firefight might push the game down to 2560 x 1440, and less intense scenes would render at 3840 x 2160, for example. This keeps the framerate steady while ensuring the game looks as good as it can at any moment. No matter what resolution the game is running at, your console will upscale it before sending along to your TV.
Checkerboarding is a modern graphics technique that helps games display at a higher resolution by, well, sort of cheating. There are several different checkerboarding methods, but the basic idea is this: The game fully draws every other pixel on each line, like drawing only the black squares on a checkerboard (hence the name). The missing pixels are “reconstructed” by using a weighted average of the neighboring pixels and data from the previous frame, together with unique data from the depth buffer. It’s a lot like 4X multisampling anti-aliasing. This cuts the work needed to draw the screen almost in half. For a full 4K image (3840 x 2160), the game essentially draws 1920 x 2160 pixels and fills in all the others with that “reconstruction filter.”
Horizon Zero Dawn uses checkerboard rendering to achieve 4K, and it looks fantastic.
It doesn’t look as quite good as actually fully rendering all 3840 x 2160 pixels, but it’s surprisingly close, and a lot better than simply dropping the resolution way down. Expect to see a lot of games use checkerboarding in the future, because the cost in quality is small compared to the improvement in performance. Game developers are always trying to strike that balance between resolution, frame rate, detail, lighting, and effects to make their games look and play their best, and checkerboarding is usually a great trade-off.
UHD stands for “Ultra High Definition” and is technically a set of standards for TVs and content authoring. It encompasses both 4K and 8K standards for home viewing.
On a purely technical level, UHD is 3840 x 2160 pixels while “4K” is the cinema standard of 4096 x 2160 pixels, but nobody actually sticks to those definitions. “4K” and “UHD” are essentially interchangeable terms these days. To differentiate the cinema resolution, some have started to call it “Cinema 4K.”
The Ultra HD Premium logo certifies a minimum 4K resolution, HDR, and wide color. But some content has those things and just doesn’t carry the logo.
The UHD definition was developed by a trade group called the UHD Alliance, and it defines more than just resolution. Ultra HD also signifies a wide color gamut (10-bit or 12-bit, as opposed to 8-bit from the HD standard), along with minimum standards for peak brightness and darkness of a display.
For the most part, you can consider UHD to be 4K and 4K to be UHD. The only place you really need to look for “Ultra HD” specifically is on Blu-ray discs. Blu-ray discs that are made for 4K are usually called “Ultra HD Blu-ray.” If you buy a regular Blu-ray disc, it’s just 1080p and uses a different video compression format.
There is no single universally accepted definition of “True 4K,” but at a minimum, we can say it means playing games at 3840 x 2160 with no upscaling or checkerboarding. The PlayStation 4 Pro is definitely capable of this. FIFA 17, NBA 2K17, Rez Infinite, and The Last of Us Remastered (in 30fps mode) are good examples of native 4K rendering. Diablo 3 features dynamic resolution that maxes out at 3840 x 2160, too.
The Last of Us Remastered runs at native 4K with HDR, and looks fantastic.
But the vast majority of “4K” games on the PS4 Pro are either upscaled from a sub-4K resolution, or use checkerboarding, or both. And while running a game at something like 1800p is not “True 4K,” of course it still looks way sharper than 1080p.
Then there’s the issue of texture resolution. The PS4 Pro makes an extra half gigabyte of RAM available for game developers. That takes the amount of RAM available for games from 5GB to 5.5GB. That’s not nearly enough to use significantly higher-resolution textures or more detailed models than the base PS4. In fact, the frame buffer (the memory used by the final drawn frame) essentially eats up all that extra space. So even when PS4 Pro a game runs at 4K, it uses the same art assets as the PS4. There are those who argue that this means the PS4 Pro cannot be called a “True 4K” console.
As with the PS4 Pro, the Xbox One X runs some games at a native rendering resolution of 3840 x 2160 with no checkerboarding or upscaling. Other games may be labeled “4K Ultra HD” on the box but utilize some of these clever techniques, or dynamic resolution.
Until the console is released, we don’t know exactly which games are using those techniques and which are not, but we already know games like Killer Instinct and Forza Motorsport 7 will render at full 3840 x 2160 with no upscaling or shortcuts. The list of native 4K games with no tricks will likely be a lot longer on Xbox One X than PS4 Pro.
Forza 7 is a showcase for the power of Xbox One X, running at native 4K with enhanced textures and effects.
What about textures? Here, Microsoft’s new Xbox offers a big improvement over the PS4 Pro. The Xbox One gave developers access to 5GB of RAM, just like the PS4. But while the PS4 Pro only makes an extra half-gigabyte available, the Xbox One X gives developers an extra 4GB. Going from 5GB to 9GB…that’s an extra 80 percent! All this extra RAM, plus a lot more memory bandwidth than the PS4 Pro, means developers can use much higher-resolution textures. Microsoft calls them “4K textures.”
This is the main reason Microsoft claims the Xbox One X is “True 4K” and the PS4 Pro isn’t: It’s not just rendering last-gen games at a higher resolution, it’s also enabling developers to provide super sharp textures and detailed 3D models. Also, the built-in video capture on the PS4 Pro only records up to 1080p, while the Xbox One X records up to 4K with HDR.
Digital Foundry’s excellent comparison of Rise of the Tomb Raider on PS4 Pro vs Xbox One X makes Microsoft’s point. It’s not just render resolution, it’s textures and effects too. (source: Digital Foundry)
Both the PS4 Pro and Xbox One X will have plenty of games that render at a sub-4K resolution, but the Xbox One X should hit that mark on more titles, and with higher-resolution textures and models to boot. Does that make one system “True 4K” and the other one not? That’s for you to decide.
Absolutely not. 3D TVs were full of compromises. You had to wear special glasses and sit in just the right spot, and anyone not wearing the glasses saw a ghostly double-image rather than just seeing the image in 2D. There wasn’t a whole lot of 3D content, either.
4K has immediate benefits for everyone without requiring any sort of special way to view it outside of owning a 4K TV. There are already way more TV shows and movies available in 4K than there ever was in 3D, with a whole lot more on the way. And of course, virtually every new smartphone shoots 4K video. How many of them ever shot 3D video?
4K is already abundant and will be the expected standard in just a few years. We’re currently at the inflection point where the TVs are inexpensive enough, and the content widespread enough, for 4K adoption to really take off. It’s already being adopted way more quickly than HD was.
Unless you’re a professional video editor, these higher resolutions can safely be ignored. 5K is essentially a resolution for computer monitors only. At 5120 x 2880, it’s one-third larger than 4K in width and height. There’s no real standard for 5K TVs or 5K video distribution, though.
6K (6144 x 3160) is mostly just a video format for high-end digital cinema cameras like the RED Weapon. Most movies for the cinema aren’t even mastered at resolutions above 4K, but shooting at a higher resolution lets editors zoom in, crop, and pan without losing detail. For consumers, 6K isn’t a thing and probably won’t ever be.
8K, however, might eventually end up in your living room one day. The UHD Alliance defined 8K standards at the same time as 4K standards, just to prepare for the future. With a resolution of 7680 x 4320, 8K has four times as many pixels as 4K and 16 times as many as 1080p. There are a couple of 8K monitors out there (mainly for professional video editors) and Sharp has even announced an obscenely expensive 8K TV. But at 4K, the pixels are already so tiny— even on big 65-inch screens— that the improvement you get by jumping to 8K is negligible. You need to sit pretty damn close to a really, really huge screen to see the benefit of 8K. Affordable giant 8K TVs are a long way off.
Want more 4K news, features, and reviews? Check out IGN's tech section for more. Think we're missing something from our 4K FAQ? Sound off in the comments!
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