NHK details higher definition TV
Jun 7, 2004 12:00 PM
Japanese national broadcaster NHK is working on ultra high definition video (UHDV), a technology being billed as a successor to today’s HDTV.
UHDV has a resolution 16 times greater than conventional HDTV, and its stated goal is to achieve a level of sensory immersion that approximates actually being there.
At a picture size of 7680x4320 pixels — that works out to 32 million pixels —UHDV’s resolution leaps frogs even that of high-end digital still cameras. HDTV, by comparison, has about two million pixels, and standard-definition TV about 200,000 (and only 480 lines of horizontal resolution versus 4000 with UHDV). The format’s beefed-up refresh rate is 60 fps (twice that of conventional video) and includes more than 20 channels of audio.
The UHDV standard is not targeted to homes, but for presentation applications in museums, hospitals, shopping malls or other venues where a high representation of detail is desired.
The standard, said NHK, is still in the early stages of development. UHDV will take many years, according to Fumio Okano, a researcher with the network. But he noted that NHK began work on the current HDTV standard in 1964, and the first high-definition content arrived only in 1982.
John Lowry of Lowry Digital Images, an imaging company in Burbank, CA, told the Times resolution is only one of the key measurements. Perhaps even more important than pixels, he said, is the dynamic range of an image, which is measured in terms of contrast ratio. The eye can perceive contrasts between the brightest white and the darkest black of roughly 100,000 to one, whereas today’s best projectors can only muster levels of about 4000 to one.
So while current projection technology cannot meet the demands of UHDV, the standard excels in other crucial areas, such as breadth of view. While both UHDV and HDTV use the widescreen 16:9 aspect ratio (standard TV uses 4:3), HDTV offers only a 30-degree field of view horizontally, whereas UHDV’s massive screen size expands this to about 100 degrees, said Okano, who said his research indicates that this angle is where immersive sensation peaks.
In developing UHDV, NHK has also focused on sound. The standard calls for 22.2 sound: 10 speakers at ear level, nine above and three below, with another two for low frequency effects. It is a setup that is well beyond the level of the 5.1 surround systems currently in use.
All those sound channels and image pixels add up to a massive amount of data. In test, an 18-minute UHDV video consumed 3.5TBs of storage (equivalent to about 750 DVD’s). The data was transmitted over 16 channels at a total rate of 24 Gb/s per second, thousands of times faster than a typical DSL connection.
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