How Ultra-High Definition Functions

For tech enthusiasts everywhere, high definition television is the latest sensation. In the United States, there's a big push for HDTV as broadcasting shifts from analog and digital signals to fully digital transmissions. Although high definition TV (HDTV) can be broadcast through both signal types, digital transmission generally offers superior quality, which is why it's the preferred method for broadcasting.

Before we proceed, it's important to clear up a common misconception: Digital TV (DTV) and HDTV are not synonymous, even though they're often used interchangeably in casual conversation. DTV refers to the method of broadcasting, while HDTV pertains to the specific format of the broadcast. DTV can also transmit in other formats like standard definition (SDTV) through digital signals. We'll explore the distinctions between these formats later. For a deeper understanding of television, see 'How Television Works.'

The journey to elevate HDTV to an internationally recognized standard is ongoing, tracing back to its humble beginnings decades ago. Given the lengthy process of developing and introducing new technologies, engineers are already working on the next stage beyond HDTV. This is where ultra-high definition TV comes into play.

Ultra-high definition TV is still primarily in the prototype phase. It was developed by engineers at the NHK Science and Technical Research Laboratories (Nippon Hoso Kyokai, also known as the Japan Broadcasting Corporation). If you come across the term super hi-vision (SHV), it likely refers to this same technology, as well as terms like ultra-high definition video or UHDV. These terms come in various versions, often hyphenated, combined, or capitalized differently. To keep things clear, we'll simply refer to it as ultra-high definition TV or UHDTV in this article.

The aim of UHDTV is to deliver an immersive television experience where the boundary between reality and TV viewing is almost indistinguishable. Manufacturers claim that when watching ultra-high definition TV, viewers will feel as though they're part of the action in a scene.

Now that we've sorted out the confusion of various names and acronyms related to TV technology, let's dive into the differences between the various levels of definition and explore what makes the UHDTV format so cutting-edge.

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Advancing Ultra-high Definition Technology

Just when you thought your TV was the peak of technology, something bigger (and possibly better) is on the horizon. Engineers are working on developing systems that surpass the current broadcasting technology, hardware, and consumer electronics such as TVs and video cameras.

NHK first engaged with HDTV technology in 1964 [source: Heingartner]. Thirty-one years later, the concept of ultra-high definition TV began to take shape. In 2002, NHK engineers showcased the first public demonstration of a prototype UHD video system, and since then, the research has continued. Engineers are working to refine the quality of UHDTV systems, software, and hardware, since all this technology has to be built from the ground up. Think of it like the leap from the rotary phone to modern cell phones.

Some of the experiments being conducted include finding ways to enhance image quality, increase signal transfer speeds, and create the best possible viewing experience. NHK aims to start producing experimental satellite broadcasts by 2015 and have the technology fully operational in Japan by 2025. So far, there have been several demonstrations, installations, and live relay tests, including one from Kamogawa Sea World to the NHK lab headquarters.

In simple terms, the key difference between ultra-high definition and high definition lies in the viewing experience. The focus of UHDTV development is to deliver more information to viewers in a way that enhances the realism of what they are watching.

Before diving into the technicalities, let's take a moment to discuss how NHK engineers developed this groundbreaking technology and the hurdles they encountered. For instance, building a projector capable of displaying UHDTV is one thing, but where do you source an ultra-high definition image to begin with? You certainly haven't seen such an image on your home TV, through your video camera, or even at the movie theater. In other words, NHK also had to create a camera, a camera control unit, and other necessary equipment to record and process UHDTV video.

Then there's the challenge of signal transmission. We're dealing with an incredibly data-heavy video signal, so managing large volumes of information became a critical part of the technology's development. Transmission also involves several different needs. For instance, transmission could occur from the recording location to the viewing location, as in live TV broadcasts. Alternatively, the signal could be transmitted from the filming location to storage, such as with movies or standard broadcast TV. Researchers had to develop equipment and software to encode, compress, and store these enormous amounts of data.

Now that we've examined the development process behind this TV technology and learned about the work going into UHDTV, are we ready to see the big picture? Click to the next page for the full details.

HDTV vs. UHDTV

To grasp the concept of UHDTV more clearly, let's dive into the details and explore how it differs from HDTV. Here's a general overview of standard television formats and their pixel capabilities. For a deeper dive, check out How HDTV Works.

Before we get into the comparison of HDTV and UHDTV, let's start by defining some key television terms:

The aim is for ultra-high definition TVs to offer 16 times the resolution of today's high definition. It will surpass the resolution of 70 millimeter film, the format used in IMAX movies [source: Hamasaki]. These images will feature 32 million pixels, compared to the two million pixels in HD. This massive resolution results in large screens, with consumer versions ranging from 100 to 200 inches (254 to 508 centimeters), and commercial versions, used for education, security, and advertising at events, could be as large as 350 to 600 inches (889 to 1,524 centimeters).

Although UHDTV offers much greater resolution and a higher frame rate, it plans to keep the 16:9 aspect ratio found in HDTV. This decision helps ensure compatibility with existing HDTV broadcasts. Researchers believe that a wide viewing angle enhances the sense of immersion, though they also acknowledge the potential issues with an excessively wide, overly realistic image. Studies are ongoing to understand these effects, such as how screen width, viewing angle, and distance influence the viewer's experience.

Ultra-high definition images may have some challenges, which researchers are working to address. For instance, watching UHDTV might cause symptoms like motion sickness, depending on the stability of the image, visual stimuli, and the viewing angle. On the production side, Hollywood has already adapted to HDTV's high level of detail (which can highlight wrinkles, blemishes, and other imperfections) — imagine the challenges makeup artists would face if UHDTV becomes the standard format for movies.

While we've explored the basics of ultra-high definition TV, there's still much more to uncover about its sophisticated technology. Continue to the next page for an inside look at the advanced mechanics that make UHDTV so cutting-edge.

Ultra-high Definition Equipment

Now that we have a clearer picture of what ultra-high definition could offer, let's take a deeper dive into how it's produced. UHDTV screens are packed with an astounding 4,000 horizontal scanning lines, and these pixels are refreshed at an incredible 60 times per second.

The massive volume of data involved in UHDTV requires precise handling, which is why a significant portion of the research and development is focused on compressing the signals to make them feasible for broadcasting. NHK researchers are designing systems that can efficiently compress signals, allowing them to handle much more than what’s necessary for standard high definition broadcasts.

As UHDTV technology continues to evolve, so too will the methods used to record, manipulate, transmit, project, and store the signals. However, here's how the current system works: An 8K video camera, capable of capturing 8,000 x 4,000 pixels, records the scene using a 4-pickup system. This system includes four imagers, each outfitted with a prism that separates the optical signal and captures either red, blue, or one of two green segments of the spectrum.

In the animation above, we get a closer look at the next steps. The image data is transformed into HD-SDI format, then split into 16 distinct channels, each representing a standard HD signal. HD-SDI, which stands for high definition serial digital interface, is a widely used format for transmitting data through short-range electrical signals. HD-SDI is particularly useful here as it enables fast transmission of large amounts of uncompressed video between various parts of the ultra-high definition system. This method also ensures that UHDTV systems are compatible with existing HDTV systems.

The 16 channels are then encoded and compressed, bringing them together for optical transmission and broadcast. Developers are keen on maintaining compatibility by using the MPEG-2 coding format, which is widely used for HDTV. Once the signals reach their destination, they are decoded, uncompressed, and split back into 16 channels as the process is reversed.

The image, now in HD-SDI format again, travels along another set of 16 cables to be further combined and projected onto a screen. Any fluctuations or synchronization issues between the merged channels or the four color segments of the projection could trigger motion sickness. Careful attention is given to perfectly align the data streams and projected images. Several techniques are employed for sharpening, filtering, processing, and correcting the image to enhance its resolution.