High Dynamic Range TV
HIGH DYNAMIC RANGE TV: WHAT’S IN IT FOR YOU?
As you consider getting a more advanced TV set, you face a bewildering array of options for improved picture and sound. The most obvious change in standards is the move from conventional HD to 4K or Ultra HD. The difference is simply the packing of more pixels onto the screen. The conventional HD picture is 1080 rows high, 1960 columns wide. 4K, as the name implies, has four times the number of pixels. Some manufacturers are even developing 8K sets.
There are limits, though, to the extent your viewing experience can be improved just by the addition of pixels. To start with, when you upgraded from 480p to a 1080p HD set, you probably got a much larger screen. The massive increase in screen size would, by itself, have profoundly affected the way you watch TV. Electronics manufacturers, though, are producing 4K sets in the same sizes as their conventional HD Sets. It’s difficult to discern much of a difference in picture quality between 4K and conventional HD, anyway, unless you’re sitting fairly close to the screen. If you’re sitting more than six feet away, you probably won’t see any difference.
Besides, there isn’t much video content available in 4K or Ultra HD, and there won’t be for a long time. The additional pixels mean that cinematographers, editors, broadcasters, and internet service providers have to handle four times as much data, an enormous headache and expense for a relatively small payoff.
High Dynamic Range (HDR) is a much subtler way to improve quality. HDR is not just a brute force approach of cramming more pixels onto the screen, it is a dramatic increase in light sensitivity and contrast. Dynamic range is the spread between the brightest and the darkest areas of an image. The greater the contrast between light and dark, the higher the dynamic range is. You may have tried adjusting the dynamic range in still photography. Lower F-stops bring lower light levels. You get deeper blacks, and more subtlety in shadows, but you lose the lightest and brightest colors, and you lose nuance in the highlights. Raise the F-stop, and you have the opposite problem. Tone mapping improves contrast, producing deeper blacks and brighter colors, but it loses detail and subtlety in the midrange, and on video it can produce flickering or other artifacts that interfere with realism.
Recent developments in High Dynamic Range video, though, have overcome these limitations. Within the last two years, several video production studios and electronics firms have found ways to produce video with higher contrast, but with a wider color gamut in the midrange, far greater detail and subtlety in shadows, and without the registration problems and the artifacts that mar older tone mapping methods.
To understand what High Dynamic Range can do for TV, it helps to know how we perceive light. Light intensity is measured in ‘nits’. Noonday sun at latitudes near the equator is as high as 1.6 billion nits, the faintest visible stars are at 0.0001 nits, while the human eye can discern up to 10.000 nits. Most TV sets, though, are color-graded for only 100 nits. A few of the more advanced ones are color-graded at 400 nits. HDR TV sets can be graded at up to 40.000 nits, and Dolby has already demonstrated Dolby Vision video at 20,000 nits, two hundred times the standard dynamic range. The HDR picture comes far closer to replicating what the human eye sees than anything else that has yet been developed. At a recent trade show, electronics and entertainment executives raved about HDR. Darcy Ellis, the CEO of Vubiquity, said, “It’s not just the number of the pixels. It’s the quality of the pixels. Those of you who have seen high dynamic range, have really seen a color palette you’ve never seen before. It is stunning.”
High Dynamic Range video requires about 25% more information than conventional HD video does. This is well short of the 300% increase required by 4K and Ultra HD, however, and so will be easier for camera operators, editors, broadcasters and internet service providers to accommodate. It also produces a much more obvious improvement in picture quality. Expect the industry, then, to place more emphasis on HDR than 4K or Ultra HD in the future. The higher potential payoff, with lower additional difficulty and expense, make High Dynamic Range TV too tempting to ignore.
High Dynamic Range TV is in its infancy. It may be one or two years, then, before you see affordable HDR sets or much HDR content. It will take time for the video and electronics industries to adapt to the new standards. Still, Sony and Samsung have demonstrated HDR sets, Disney has already shot video content for the new standard, and Dolby will release consumer software that will adapt a conventional HD TV set to HDR. Keep your eyes and ears open. You’re likely to hear much more about High Dynamic Range TV very soon.
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