What is HDR (High Dynamic Range)?

High dynamic range (HDR) video is one of the newest HDTV feature bullet points. It could push video content past the (now non-existant) limitations to which broadcast and other media standards have adhered to for decades. But adoption could be slow over the next few years because it's a complicated and somewhat esoteric feature.

Standard Dynamic Range
HDTV contrast is the difference between how dark and bright it can get. Dynamic range describes the extremes in that difference, and how much detail can be shown in between. Essentially, dynamic range is display contrast, and HDR represents broadening that contrast. However, just expanding the range between bright and dark is insufficient to improve a picture's detail. Whether a panel can reach 100 cd/m2 (relatively dim) or 500 cd/m2 (incredibly bright), and whether its black levels are 0.1 (washed out, nearly gray) or 0.005 (incredibly dark), it can ultimately only show so much information based on the signal it's receiving.

Current popular video formats, including broadcast television and Blu-ray discs, are limited by standards built around the physical boundaries presented by older technologies. Black is set to only so black, because as Christopher Guest eloquently wrote, it could get none more black. Similarly, white could only get so bright within the limitations of display technology. Now, with organic LED (OLED) and local dimming LED backlighting systems on newer LCD panels, that range is increasing. They can reach further extremes, but video formats can't take advantage of it. Only so much information is presented in the signal, and an HDTV capable of reaching beyond those limits still has to stretch and work with the information present.

What Is HDR?
That's where HDR video comes in. It removes the limitations presented by older video signals and provides information about brightness and color across a much wider range. HDR-capable displays can read that information and show an image built from a wider gamut of color and brightness. Besides the wider range, HDR video simply contains more data to describe more steps in between the extremes. This means that very bright objects and very dark objects on the same screen can be shown very bright and very dark if the display supports it, with all of the necessary steps in between described in the signal and not synthesized by the image processor.

To put it more simply, HDR content on HDR-compatible HDTVs can get brighter and darker at the same time, and show more shades of gray in between. Similarly, they can produce deeper and more vivid reds, greens, and blues, and show more shades in between. Deep shadows aren't simply black voids; more details can be seen in the darkness, while the picture stays very dark. Bright shots aren't simply sunny, vivid pictures; fine details in the brightest surfaces remain clear. Vivid objects aren't simply saturated; more shades of colors can be seen.

This requires much more data, and like ultra high-definition video, current optical media can't handle it. Blu-ray discs cannot hold HDR information. That will change over the next few years as the UHD Alliance pushes the Ultra HD Blu-ray standard. It's a disc type that can hold more data, and is built to contain 4K video, HDR video, and even object-based surround sound like Dolby Atmos. It could solve all of the distribution problems of 4K and HDR without requiring a very fast Internet connection. Online streaming will still be a valid way to offer 4K and HDR video, but Ultra HD, Blu-ray provides a physical and broadly accessible way to get it.

What You'll Need
Don't expect to see these discs on your Blu-ray player, though. While they're called Blu-ray discs, they still use different technology and different encoding standards to stuff all of that information onto the medium. You'll need an Ultra HD, Blu-ray player to use these new discs. We'll see if some players will be able to read this media with firmware upgrades in the future, but for now it seems that new players will be necessary.

You'll need an HDR-compatible HDTV, as well. HDR is not 4K. A 4K screen might support HDR, but that doesn't apply to all sets. If your HDTV doesn't support HDR, it won't take advantage of the additional information in the signal, and the panel isn't calibrated to handle that information if it was properly read. So, if you haven't picked up a 4K television yet, you might want to wait for an HDR-compatible one that fits your needs in the future. If you have, don't fret; HDR content is even newer and rare than 4K video, and we won't see it become widely available for a while. The HDR content situation was similar to the 4K video situation three years ago; what's out there is mostly there to show off the technology rather than present a really compelling, broad reason for consumers to adopt it just yet.

Where Is it Now?
Currently, Amazon, 20th Century Fox, Universal, BBC, LG, Broadcom, the UHD Alliance, the CEA, and other organizations are working on standards and distribution methods for HDR content. LG has been promoting its OLED televisions as being HDR-capable, as having Samsung with its own high-end LED televisions. HDR video remains very limited, with only some movies available through a very specific distribution method, like hard drives with the HDR films preloaded on them to ship with HDR-compatible HDTVs.

We'll be keeping an eye out for more HDR news and products as they come out. Expect new HDR displays and content to appear in January at CES 2016.