The High Dynamic Range Video Revolution is Coming—Are you Ready?
August 8, 2017
Jacob Schwarz and Mystery Box shot a recent project in Peru using an 8K Red Helium Camera. When shooting HDR, “You want to make sure that you retain as much highlight detail as possible,” says Schwarz.
Software packages such as Blackmagic Design’s DaVinci Resolve can be used to grade and master HDR video. Many can also automate the processes and conversions needed to optimize HDR video for different displays and distributors.
At times, the relentless upward trajectory of imaging specs can feel like a numbers game invented to keep creative types scrambling, hamster-like, on the upgrade wheel. But every once in a while there’s an advance that makes you feel like you’re getting your money’s worth. For many filmmakers, high dynamic range (HDR) video represents one of those leaps forward. On the most basic level, HDR video simply offers a healthy increase in the number of brightness values that can be displayed in a film. But spec-weary viewers who have shrugged at resolution increases—the jump from HD to 4K, for example—have snapped to attention when they see the dramatically richer and more realistic imagery made possible by HDR.
Unlike HDR photography, HDR video isn’t based on exposure composites and doesn’t need tone mapping to squeeze itself back into the inadequate parameters of a display with a peak brightness of no more than 300 nits (i.e., candelas per square meter) and an sRGB or Rec 709 color gamut. Instead, it lets the broad dynamic ranges that many camera sensors are already capable of capturing express their full potential. That’s thanks to a new breed of 4K HDR TVs and monitors that are capable of peak brightness levels of 600, 1,000 or even 4,000 nits, have much higher contrast ratios, and use larger color gamuts like DCI-P3, Rec 2020 and eventually Rec 2100.
There’s another important difference from HDR photography: HDR video isn’t just an image-editing option that, after an initial burst of popularity, will politely take its place alongside myriad other tools that image creators can choose to apply or ignore. HDR video is the future of how video will be recorded. And the future is now. If you’re shooting motion or planning to add it to your repertoire, it’s time to get up to speed.
According to Steve Koenig, Senior Director of Market Research at the Consumer Technology Association (CTA), 9 million of the 40 million displays projected to be sold in 2017 will support HDR. “Our forecast horizon is 2020,” he says, “and by that time we’re predicting roughly 50 percent of TVs will support HDR.” Content producers and distributors such as Netflix, Amazon, YouTube and Hollywood studios are driving the adoption of HDR. They’re both producing and soliciting content that has been mastered in the new Dolby Vision and HDR10 standards for HDR video.
As with any nascent technology, there are multiple standards competing for attention. Fortunately, the way they will shake out seems clear, with the proprietary 12-bit Dolby Vision standard occupying the high end of the market, the 10-bit HDR10 open standard being the most commonly used, and Hybrid Log-Gamma (HLG) reserved mainly for live broadcasting. Dolby Vision will be supported in premium TVs, and large content producers like movie studios and Netflix will pay the fees required to master their productions in the format. Smaller production houses and independent filmmakers will work in HDR10, which will be supported by the vast majority of HDR TVs. “It’s going to be able to maximize the reach of that video,” says Koenig of the HDR10 standard.
The good news for filmmakers is that if you’ve been shooting video to a RAW or log format with at least 10-bit color depth, you’re already shooting for HDR10 postproduction. If your camera can’t meet those specifications, it’s worth upgrading or paying a higher rental cost to produce files that can be mastered for HDR display. “If you have more bits, obviously you’re going to be able to fit those bits more correctly into your space, into your final delivery,” says filmmaker Jacob Schwarz, who has been shooting and mastering HDR10 projects for the past two years with his Pleasant Grove, Utah-based production company, Mystery Box. Schwarz has used RED and Sony cameras to output 16-bit RAW files and considers 12-bit files a reasonable option and 10-bit files the bare minimum for working with HDR10.
When it comes to shooting for HDR, Schwarz says the main difference is that getting exposures right is more critically important than ever. “You want to make sure that you retain as much highlight detail as possible,” he says. “In the past, the TVs and displays could never actually distinguish it. At one point they all just went bright white,” he observes. “And now we’re in a world where we’re trying to distinguish how many nits are assigned to each individual pixel that’s being reproduced rather than just whether it’s white or bright.” It’s also important to keep an eye on shadow details that would be obscured in standard video with less dynamic range.
Being able to see all of those details when you’re grading and mastering HDR video is essential, which makes an HDR monitor the major new piece of equipment required for an HDR video workflow. While the earliest HDR reference monitors ran into the tens of thousands of dollars and Dolby Vision output can only be mastered on high-priced, Dolby-licensed equipment, manufacturers from Dell to EIZO have recently unveiled more affordable HDR monitors that can be used for HDR10 mastering. However, the peak brightness levels and other parameters of the new monitors vary widely so the specs need a close read. In addition to a peak brightness of at least 1,000 nits, look for 4K resolution, high contrast ratios, support for over 90 percent of the DCI-P3 color gamut, and support for the Perceptual Quantizer (PQ) curve that the HDR10 standard uses to tell displays how to translate video data into light.
Both Dolby Vision and HDR10 use the PQ curve, which replaces the gamma curves used to grade and correct standard dynamic range video. “The PQ curve is built for a theoretical display that is set to 10,000 nits,” explains Matt Tomlinson, SVP Imaging Science at the international postproduction house SHED. Because the HDR10 standard requires that the peak brightness of the display be specified in the video metadata, video editors have to choose a level that they think will be appropriate for the majority of the displays their content will be viewed on. “People are kind of settling in at this moment at about 1,000 nits,” says Tomlinson. “I think that’s going to increase over time.”
In addition to potentially having to create different versions of the same video for displays with different peak brightness levels, postproduction houses often need to deliver standard dynamic-range versions to distributors. Does that mean HDR will exponentially increase your postproduction workload? “Nope, not really,” says Schwarz. “We have a standardized LUT that converts it down.” While it required a little time for Mystery Box to create the LUTs they use to convert their HDR10 masters for different display types, applying them automates the process for every production. Aside from such customized solutions, the software packages commonly used for grading and mastering HDR video can also automate many typical processes and conversions. Blackmagic Design’s DaVinci Resolve, one of the most popular options, comes in free versions or for a reasonable $299.
For filmmakers handling their own postproduction, the steepest learning curve will be in understanding the parameters to feed into the software and getting accustomed to working with the PQ curve. “The biggest thing to understand is color management and color science to a certain degree,” says Keith Roush, a colorist who has worked on numerous HDR productions. “For example, you can take a raw image and use Resolve color management and tell it that it’s going to go out to Rec 2020 at a 1,000 nit SMPTE 2048, which refers to the transfer curve. As long as you know that information, then the software largely does the really heavy lifting for you and it will put a correct image onto an HDR monitor.”
Getting a handle on the new HDR tools and specs is quickly becoming de rigueur for professional filmmakers. But if the prospect of spending time and money on yet another whiz-bang upgrade doesn’t thrill you, take comfort in the fact that you can expect some creative gratification. “We have a bigger canvas to paint on now,” says Roush. “In the future we won’t even be talking about Rec 709 or standard dynamic range, because HDR will replace that altogether, and it will just be what we’re used to seeing. And it’s not that far away.”