How Ultra-high Definition Works

HDTV Image Gallery Although high definition is at the height of cool right now, there are even bigger advances on the horizon.  See more HDTV pictures.
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For gadget gurus everywhere, high definition television is all the rage right now. The United States is giving high definition TV a big push by switching broadcasting standards from the use of analog and digital signals to exclusively digital signals. Although high definition TV (HDTV) can be broadcast through both types of signals, the quality seems to be better with digital, which is generally how the images are broadcast.

But before we move on, let's clarify: Digital TV (DTV) and HDTV don't have the same meanings, even though they're sometimes used interchangeably in casual conversation. DTV refers to the manner in which something is broadcast; HDTV refers to the format it's broadcast in. DTV can also be broadcast through digital signals in other formats, such as standard definition (SDTV). The differences of these formats will be discussed later in this article. For a more detailed look at television, read How Television Works.


Bringing HDTV to the level of an internationally recognized standard format, from its humble origins a couple of decades back, is still going on. Because the process of developing and marketing new technologies is so lengthy, engineers have already started the task of developing the technology that'll proceed HDTV. This is where ultra-high definition TV comes in.

Ultra-high definition TV is still largely in the prototype stages. It was pioneered by engineers at the NHK Science and Technical Research Laboratories (Nippon Hoso Kyokai, also known as the Japan Broadcasting Corporation). If you hear about super hi-vision (SHV), you're probably hearing a reference to this same technology, as well as if someone says ultra-high definition video or UHDV. There are many different versions of these terms, either hyphenated, combined and/or capitalized in varying ways. To avoid confusion, in this article we'll simply use the term ultra-high definition TV or UHDTV.

UHDTV's goal is to create a vivid, television-watching experience, where the lines of realism and television are blurred. According to manufacturers, people will watch ultra-high definition TV and feel like they're in the middle of a scene.

Now that we've cleared through the mess of monikers and acronyms surrounding TV technology, let's jump into the differences between the various levels of definition, and find out what's so advanced about the UHDTV format.



Developing Ultra-high Definition Technology

Ultra-high definition has already been put to use in at least one commercial venue. Theater 4000 was built in October 2005 at the Kyushu National Museum in Japan.
Eriko Koga/The Image Bank/Getty Images

Just when you thought your TV was state-of-the-art, something bigger (and possibly better) is coming along. Engineers are working to develop technology that goes far beyond the capabilities of current broadcasting systems, hardware and household electronics such as TVs and video cameras.

NHK first got involved with HDTV technology back in 1964 [source: Heingartner]. Thirty-one years later and studies concerning ultra-high definition TV began to take form. In 2002, NHK engineers put on the first public demo of a prototype ultra-high definition video system, and from there, the research continued. Researchers are working to improve the quality of the UHDTV system, software and equipment, because all this technology must be developed and built from scratch. Let's put it this way -- think about the far-spanning innovations needed to make cell phones a reality out of their predecessor, the rotary phone.


Some of the experiments the technicians are doing include devising ways to perfect the image appearance, speed signal transfer rates and create the optimum viewing experience. NHK's goal is to begin producing experimental satellite broadcasts in 2015, and have the technology ready to roll in Japan by 2025. So far they have had a number of demonstrations, installations and live relay experiments, like the one from Kamogawa Sea World to NHK lab headquarters.

To put it simply, the main way ultra-high definition differs from high definition is in the quality of the viewing experience. The focus of the UHDTV development efforts revolve around the idea of delivering more information to the viewer, in a way that increases the realism of the viewing experience.

But before we get into the technical details, let's talk more about how NHK engineers went about developing this technology and the challenges they faced. For example, it's all well and good to build a projector that can display UHDTV, but where do you get an ultra-high definition image from in the first place? You've certainly never seen an image like that on your home television screen, through your video camera or even at the movie theater. In other words, NHK also needed to develop a camera, a camera control unit and other equipment that would record and process ultra-high definition video images.

Then there's the signal transmission. We're talking about an extremely data-laden video signal here, so strategies for handling large volumes of information became a central concern of the technology's development. Transmission can also encompass a couple of different necessities. For example, transmission could take place from where the images and sounds are recorded to where they're viewed, like in the case of live TV. Or, the signals could be transmitted from where they're filmed to where they're stored, like in the case of movies or standard broadcast television. Researchers also needed to develop equipment and programs that could encode, compress and store these vast amounts of data.

Now that we've had a closer look at the plans for this TV technology and read about the work that's going into developing UHDTV, are we ready to see the big picture? Click to the next page for the scoop.



How Stuff Works

In order to better understand UHDTV, let's examine the details and discover the differences between it and HDTV. Here's a general breakdown of the standard television formats and their pixel power. For a closer look, read How HDTV Works.

We'll get into HDTV vs. UHDTV in a moment, but let's first examine the basic terms regarding television:


  • Resolution is determined by the number of pixels that are arranged horizontally and vertically across the screen. A pixel is the smallest possible individual point of light that makes up an image on a screen. Depending on the density of pixels (or dots per inch), the more pixels that comprise an image, the clearer it will become generally. The first number, 1920 for example, represents the number of pixels in each row running horizontally across the screen. The second number, 1080, refers to the amount of pixels in each vertical column. The second number also refers to the amount of scanning lines a screen has. UHDTV, for example, is reported to have 4,000 scanning lines.
  • The aspect ratio describes the proportions of the width and height of the screen. Think of the difference between today's rectangular, slim TVs and the square-shaped screens of bulky TVs used 10 years ago -- those older models featured a 4:3 aspect ratio. Nowadays, you're likely looking at a TV with a 16:9 aspect ratio -- the same as a movie theater screen.
  • The frame rate describes how many times per second the picture refreshes on the screen. The lowercase letter listed after the number indicates the manner in which this process is completed. The "i" means the image is interlaced: every other scanning line of pixels is refreshed, with the other half following suit. A "p" signifies the change is progressive, and the entire image is being refreshed constantly.

The plan is that ultra-high definition TVs will have 16 times the resolution of anything we currently have now in high definition. It'll be more than twice the resolution of 70 millimeter film, a commonly used format for IMAX movies [source: Hamasaki]. The projected images will be crammed with 32 million pixels, compared to the current HD experience that displays about two million pixels. With these huge numbers, not only is the image resolution exceptionally rich, the screen ends up being quite large. Developers expect the consumer versions will be between about 100 and 200 inches (254 and 508 centimeters) in size. Commercial versions -- possibly used for educational, security and advertising purposes at sporting events, art shows and museums -- would be more along the lines of about 350 to 600 inches (889 to 1,524 centimeters).

Despite the differences in resolution and frame rate, the current plan is to retain HDTV's aspect ratio of 16:9, as opposed to choosing a new one like IMAX developers did. This will help keep the new equipment compatible with HDTV broadcasts. Researchers believe that a wide viewing angle increases the sensation of immersion, although they also recognize the drawbacks that can come with a too-wide, too-realistic depiction of images. Studies into these phenomenon are being conducted to help guide UHDTV's development. For example, researchers examine the sensation of presence according to the width of the screen and the optimum angle and distance from which to view it.

Ultra-high definition images could also have a few drawbacks that researchers are trying to solve. For example, someone watching UHDTV might experience symptoms such as motion sickness depending on the stability of the image, the amount of visual stimuli and the visual angles he or she is viewing the TV at. On the production end of the process, Hollywood has already had to adjust to HDTV's unforgiving detailed image (the technology can magnify any wrinkles, pimples and facial imperfections) -- imagine the challenges make-up artists face if UHDTV becomes a mainstream format for movie viewing.

­Though we've delved a little deeper into the world of ultra-high definition TV, there's still super-advanced, high-tech goodness to learn about. Continue to the next page for an inside look at the cutting-edge mechanics of UHDTV technology.


Ultra-high Definition Equipment

Now that we know more about what the ultra-high definition format may be able to deliver, let's take a closer look at how it could be produced. Remember that a massive number of pixels (4,000 horizontal scanning lines worth) are crammed onto a UHDTV screen, and those pixels are refreshed at a breakneck pace of 60 times per second.

That enormous volume of data requires precision handling, so a big part of the UHDTV research and development is focused on making the signals a practical size for broadcasting purposes. NHK researchers are developing ways to successfully compress the signals before transmission, creating equipment with abilities beyond what's necessary to handle typical high definition signals.


As the UHDTV technology progresses, the manner in which developers accomplish aspects such as signal recording, manipulation, transmission, projection and storage is also likely to evolve. But, here's a basic breakdown of how the current system works: An 8K video camera, with the ability to handle 8,000 x 4,000 pixels, records the scene using a 4-pickup system -- four imagers, each equipped with a prism to separate the optical signal, gather either the red, blue or one of the two green segments.

In the animation above, we get a better look at what happens next. The image data is converted into HD-SDI format and divided into 16 separate channels, each the size of a regular HD signal. HD-SDI stands for high definition serial digital interface, and it's a standard format for transmitting data into short-distance electrical signals. HD-SDI is useful in this situation because it allows the quick transmission of large amounts of uncompressed video signals between different components of the ultra-high definition system. By using it, the engineers designing the system are also helping ensure UHDTV systems remain compatible with current HDTV systems.

Next, the 16 channels are encoded and compressed, combining them for optical transmission and broadcast. Again, developers are looking to maintain compatibility by utilizing the MPEG-2 coding format that's popular for HDTV. Once the signals reach their destination, they are decoded, uncompressed and separated back into 16 channels as the process reverses itself.

The image, returned to HD-SDI format, travels along another 16 cables to where it'll be combined further and projected onto a screen. Any fluctuation or instability caused by syncing problems between the reunited channels of information or the four color segments of the projection can be triggers for motion sickness. Great care is taken to match the data streams and projected images to a tee. A number of other techniques and actions are performed for sharpening, filtering, processing and correcting the image in order to improve its resolution.

Want to own one of these high-tech wonders? While you're waiting for an ultra-high definition TV to arrive at an electronics store near you -- a long wait, to be sure -- read the links on the next page for more information.


Lots More Information

Related HowStuffWorks Articles

More Great Links

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