Giz Explains: How 4K TV Works

Giz Explains: How 4K TV Works

Imagine 80-inch screens with quadruple the image quality of full HD, plus passive 3D content that you’d consider actually watchable. That’s 4K TV technology. It could deliver a stunning home theatre experience — just as soon as 4K-enabled TV’s like Sony’s latest begin to cost less than a car.

But what exactly is 4K, and why should you care? Here’s a brief history of the future of television.

What’s all this talk about 4KTV?

First of all, there’s 4K TV and then there’s 8K TV. They make up the lower and upper halves of the Ultra-High Definition (UHD) standard, a digital video format proposed by NHK Science & Technology Research Laboratories in 2007. Both are capable of playing footage at 24, 25, 50, 60 and even 120 frames per second (you can almost hear Peter Jackson squealing with delight).

At 2160p, 4K UHDTV is double the resolution of the current 1080p full HD standard. So at 3840×2160, it’s twice as wide, twice as tall — with an 8.3MP image that’s quadruple the 2.1MP image found on current HD. Interestingly, the term “4K” actually refers to the horizontal pixel count, even though the industry standard counts along the vertical axis.

With 8K, at twice the resolution of 4K, the display shows a staggering 7680×4320 resolution. You’d have to stack current HDTVs in two rows of four to match the bit count of a single 8K set. What’s more, 8K features a truly massive 33.2MP image — equivalent to the quality produced by top-shelf pro cameras like the Nikon D800.

However, like all brand new technologies, the UHDTV standard, especially the higher 8K range, still has a few kinks to work out. Like the fact that current network infrastructure struggles to transmit such large amounts of data. Oh, and the fact that 8K UHDTV cameras cost about a million friggin’ bucks.

NHK’s third-generation 8K prototype camera, for example, is limited to one hour of filming. That’s how fast its dual banks of 16x64GB P2 cards fill to their terabyte capacity. The camera’s 1.5-inch CMOS sensor captures 33.2MP footage shot at 120fps — that’s roughly four billion pixels per second of data, moving at a rate of 51.2GB per second, synchronously transmitted on 96 channels. The resolution is so high that focus isn’t even controlled by the cameraman. Viewfinders currently don’t have a resolution greater than 1K, so the cameraman can’t know if the shot is actually in focus, so the job is handled by a remote CCU operator.

Today’s 4K cameras aren’t nearly expensive — though dropping $US25,000 on a 4K Red One makes “expensive” a relative term. As for the difficulty of actually broadcasting so much information, Sony recently demonstrated that, utilising the h.264 compression scheme, it could successfully transmit 4K video at a rate of 50Mbps without a discernible loss of image quality. This opens the door for UHD content creators to broadcast their work somewhere other than YouTube.

What has 4KTV done for me lately?

You probably haven’t ever seen 4KTV on a consumer television — unless, of course, you had an extra 25 grand laying around last month to get the new 84-inch Sony Bravia. But you will see it.

The beauty of 4K is that it packs so much visual data onto the screen, that the pixels can be absolutely minuscule while still displaying 10 bits of data at a time. Think of an Apple Retina display, but at a higher resolution, and on an 80-inch screen — that’s UHD. To even be able to notice the individual pixels, you’d have to smash your face right up against the display.

An increased pixel count will also benefit 3DTV. Passive 3D cuts the horizontal resolution in half to create a 3D effect — so if you’re watching a 1080p movie (1920×1080) in 3D using passive glasses, you’re really watching a 1920 x 540 picture. By doubling the resolution of the whole image, 4K effectively overcomes 1080p’s limitations, producing an HD-quality 3D image. You’re in for crisper, clearer 3D movies. And research is already under way to see if a 4K image, combined with sufficiently high refresh rates, can deliver 3D images sans glasses.

As more and more companies jump on the 4K bandwagon — LG has a 3D UHD set, Sharp has Super Hi-vision, and Sony launched the 4K Home Projector — prices are expected to drop as precipitously as they did with early HDTVs. The future looks fantastic.

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