In the world of new TVs, the goalposts are always moving. As soon as you feel safe splurging on a new set, another reason to hold out comes along. First there was 3D. Then 4K. Let’s not forget about OLED and quantum dots, then cheaper 4K and cheaper OLED. This year is no exception, with another new technology offering another reason to hold your horses. It’s called HDR video, which is short for “high dynamic range.”
HDR is not about extra pixels. Every set capable of handling HDR video already can display 4K video. Instead, HDR makes images with widely varying lights and darks look better on your screen. It’s great! You totally want it. But like most nascent technologies, barriers abound for early adopters. From high prices to a dearth of video sources, there are many things to consider before you buy into HDR.
What Is HDR Video?
If the “HDR” acronym sounds familiar, it’s because you’ve seen it as a setting in your smartphone camera. The results there are not great, which means you probably think HDR sucks. For still photography, HDR is a handy (if overused) workaround to a common problem: It brings out details in the light and dark areas of a scene, usually by capturing multiple images at different exposures and merging them. The problem is, such photos often look airbrushed and fake.
HDR video is different. It looks very realistic, with gradations and nuances closer to what’s seen in real life. It can get bright enough to simulate light reflecting off chrome and dark enough to look like an oil slick. In both cases, you still see fine detail and subtle shades. HDR doesn’t fake the contrast with stupid filters and weird halo effects. Instead, it uses new panel technologies with a wider color palette in concert with specially encoded video.
For that reason, you need a specific type TV to see HDR video properly, and you need a specific type video source, too. In the best case scenario, you will see deeper and more accurate colors, and lighting effects will appear more lifelike.
How Are HDR TVs Fundamentally Different?
HDR isn’t tied to a certain type of display technology, but almost all HDR sets thus far share a few traits. Vizio, Sony, Samsung, Panasonic, LG, TCL, and Hisense all have HDR-capable TVs that are essentially super-powered LCD 4K televisions. These sets can get really bright—bright enough that looking at an onscreen sun or explosion can make you squint. These panels’ backlight systems crank up to more than 1,000 nits—by comparison, most LCD HDTVs put out around 300 or 400 nits. Why so bright? With such a high peak brightness, the contrast between light and dark (or light and lighter) areas of the scene are more pronounced.
Also, most HDR televisions aren’t OLED sets. They use LCD panels, since they can get much brighter than OLEDs. However, because OLEDs don’t have backlight systems (each pixel turns on and off individually on an OLED) they can get much darker, and therefore produce deeper blacks. Earlier this month, LG and Panasonic both announced new 4K OLED TVs that can display HDR video.
What About Colors? Are They Any Better on HDR TVs?
Yes! There are waaay more colors on these high-end 4K TVs.
That’s because both content and TVs are moving far beyond the color space and bit depth of traditional HDTVs. For displaying colors, HDTVs stick to a 25-year-old specification called Rec. 709. It’s an 8-bit color space recommendation made by a TV trade group. It’s as old as Windows 3.0 and season one of The Simpsons. It’s archaic, and it’s been supported throughout the entire HDTV era. Now we have a new spec: 4K TVs and content will take aim at the 10- to 12-bit Rec. 2020 color space, which represents more than 60 times as many distinct color combinations as Rec. 709. More than a billion of them, actually. The Rec. 2020 color gamut is even wider than the DCI-P3 color space defined for professional digital projectors (which is also much wider than Rec. 709).
From filming to mastering to distribution to display, we’re talking about an end-to-end pipeline that produces a far better picture. Content can be mastered to take advantage of a wider color space, extra metadata is piped to an HDR-capable TV to define how it looks, and color-tuning technologies such as quantum dots can help it display accurately. The combination of 4K resolution, extreme brightness, improved contrast, and more colors will be what makes HDR video look spectacular—even if the “HDR” trick itself is only part of the sauce.
Man, How Do I Make Sure My New TV Does All That?
There’s a badge now! The UHD Alliance, a group of TV manufacturers, content providers, and distribution companies, will begin issuing an “Ultra HD Premium” stamp of approval for certain TVs. These badges will be reserved for the “five-tool players” of the TV world, sets that provide a combination of tack-sharp resolution, high dynamic range, and very wide color gamut.
To qualify, a TV must have a display resolution of at least 3840×2160 (that’s 4K), support 10-bit color, be able to handle sources that use the Rec. 2020 color space, and be able to display at least 90 percent of the DCI-P3 color space. In terms of dynamic range, the Ultra HD Premium badge accommodates both LCD and OLED displays. For an LCD, a qualifying TV must have a peak brightness level higher than 1,000 nits and a black level less than 0.05 nits. For an OLED to qualify, it must have a peak brightness of at least 540 nits (remember, OLEDs cannot get super bright) and a black level less than 0.0005 nits (remember, OLEDs can get super dark).
