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Everything you need to know about 4K HDR TV

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High dynamic range (HDR) is the latest TV feature, but not all TVs do it well

If you’re buying a TV for the first time in years, get ready to learn some new jargon.

You’re going to hear a lot about smart TV being able to watch Netflix on its own. And 4K aka ultra – high – definition (UHD), whose pixels are four times that of ordinary HDTV.

But according to our testers, high dynamic range is the biggest TV feature these days.

If handled properly, TVs with HDR have higher peak brightness and wider color capabilities, enabling them to present HDR content more accurately (many movies and TV programs already have HDR content).

But not all HDR TVs do as well. Here’s what you need to know to make a good choice.


What is HDR?

In music, high dynamic range refers to the difference between the softest and loudest parts of the piece. In the video, it’s about increasing the contrast between the brightest white and darkest black the TV can produce.

“If done well, HDR will show more natural light for image content,” said Claudio ciacci, head of the consumer report TV testing program“ Although HDR requires TV to have higher peak brightness, it doesn’t mean it has to present dazzling brightness images to the audience. ” It just means that the TV has the brightness space needed to present the various elements of the image at the required brightness level – dark caves, facial highlights in the sun, bright light bulbs. ”

When HDR is working, you’ll notice the texture of the bricks on the dark aisles or the nuances of white clouds in the daytime sky.

You’ll also see brighter, more realistic “specular highlights,” such as the sun’s reflection from car chrome bumpers or airplane wings. With HDR, those flashes will suddenly appear; Without it, they would not be so prominent.

HDR TVs can also generally produce more vivid and varied colors. This is because HDR is often combined with the new “wide gamut” technology, namely WCG.

Think of it as giving your TV a bigger box of crayons to play with. Standard HDTVs can display about 17 million colors. Users with WCG can display up to 1 billion times.

But not every time you turn on the TV, you can enjoy the wonderful contrast and color. You have to play a movie or TV show to master the use of HDR and WCG. When HDR TV was first launched, it was difficult to meet these functions, but now almost all streaming media services provide this function.)

A picture of an SDR and an HDR image side by side.

The image above shows a side-by-side comparison of a standard image and an HDR image.

Although it sounds like a technology, there are several types of HDR, each with different technical specifications.

Hdr10 has been adopted as an open standard. Free to use, it supports all 4K TV and HDR, all 4K Ultra HD Blu ray players, and all HDR programming.

Many of the TV now, including LG, Vizio and several brands of roku, also offer Dubby vision as an enhanced version of hdr10. The company is required to pay for the use license. One of its advantages is that Dobby vision supports “dynamic” metadata, which allows TV to adjust brightness on a scene by scene basis or frame by frame basis. In contrast, hdr10 uses static metadata to set a brightness level for the entire movie or show.

But a new product called hdr10+ also uses dynamic metadata. It is mainly in Samsung 4K TV, which has been sold since 2017. But its popularity in the United States remains to be seen by Amazon’s 4K streaming video service and some 4K Ultra HD Blu ray discs, mainly from 20th century fox, to support it.

Dynamic metadata in Duby vision and hdr10+ can help a medium level TV set with less brightness than the top-level models adjust its content to meet the limitations of the TV. Using a process called “tone mapping”, metadata can guide TV to adjust scene by scene or frame according to the brightness, color and contrast in the content.

Some TV now supports another HDR format, called HLG, which is an abbreviation for hybrid log gamma. If it is adopted by the next generation of free wireless TV signals, it will follow a standard called ATSC 3.0, and you may hear more about it( It’s important for those watching TV over the antenna, and the antenna is coming back in the air.)

Many new TVs have built-in HLG support, and other TV can be received through firmware updates if necessary.

Yes, these sounds complicated.

But there is also some good news. First, your TV will automatically detect the HDR type used in a given movie or program and choose the right way to play it. No adjustments are required.

Second, the type of HDR seems to be less important at present. As we can see in the lab, a TV with the best performance can be done well, whether it’s hdr10 or dobby vision.

Our advice is: instead of worrying about the type of HDR, buy the best TV you can buy.

Is all HDR TV the same?

In a word, No. Our tests show that not every HDR TV set can produce the same rich and realistic images.

First, when it comes to image quality, television is all maps, HDR or no HDR. But the technology also faces specific challenges.

Most notably, the TV must be bright enough to really achieve HDR. To understand why, you need to know your “nits,” the unit used to measure brightness.

Better performance HDR TVs usually produce at least 600 naires of peak brightness, and the best performance can be 1000 naires or more. But many HDR TVs produce only 100 to 300 nits, which is really not enough to provide an HDR experience.

In the case of insufficient TV power, the rocket fire will become a huge white flare. If you have a brighter TV, you will see a stronger, more realistic flame, just as if you were there.

“The advantages of HDR are often replaced by mediocre displays,” ciacci said

How to distinguish a good HDR TV from a bad one

Unfortunately, you can’t just look at the packaging, or even just the way the pictures look in the store.

Although some TV sets have the “ultra high-end” logo, indicating that they have been certified as high-performance TV by an industry organization called UHD alliance, not all manufacturers have participated in the program. LG and Samsung have; Sony and Vizio don’t.

You can’t rely on the highest brightness the TV claims. Most of these measurements are recorded using a standard industry test pattern called 10% window, which evaluates the brightness of a small box in a completely black background. But companies can use other methods to generate peak brightness numbers.

What should we do? Check out our TV ratings and purchase guide. We now have scores for UHD image quality and HDR performance. In addition, we test brightness differently than most other publications.

Remember 10% of the window patterns? We think it is unrealistic to use it to determine the brightness of TV when watching ordinary TV programs or movies. That’s why consumer reports has developed its own brightness test mode, putting 10 percent of the white windows in the context of mobile video. So we can better understand the real brightness of the TV.

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