Producing and Grading HDR

HDR, HDR, HDR. Are you sick of hearing about HDR like I am? Dolby Vision, HLG, HDR10, HDR10+.

For the past few years, 4K has mostly dominated the popular conversation in video, but as 4K has become ever-so-slightly banal to ordinary video users, HDR has been steadily supplanting its dominance. Your customers ask for it, even though they can’t afford it. Alas! Such is our plight as producers. We try to meet our customers’ needs within their budgets, despite our personal opinions on just what exactly it is that they need. So when the customer says, “I want HDR,” we say, “No problem,” and then scurry off to figure out just how in the world to actually create HDR video.

What Is HDR?

Let’s begin with a primer on this magical world of High Dynamic Range Video. HDR is an all-encompassing term. It covers proprietary methods like Dolby Vision, but it also covers open-source solutions like HDR10+. And don’t forget about Hybrid Log Gamma (HLG, http://go2sm.com/4s).

Despite what consumer television ads may lead you to believe, HDR is not a video image with wildly overdriven saturation and brightness settings. At the core of HDR are a few key differences between itself and that crotchety old SDR.

Some simple definitions will set us in the right direction. “High” indicates that the ceiling is greater than normal. “Dynamic” refers to the contrast. Think of dynamics in music or having a dynamic personality. “Range,” of course, is a given span from end to end or high to low. In video, this refers to the brightness and contrast of the displayed image.

How Do You Deliver HDR?

Now that the boring stuff is out of the way, let’s go back to your customer. The customer wants HDR. How are you going to give him HDR? The camera you already own may be HDR-ready, and it won’t cost you anything to enable HDR recording, although you will likely need some extra cash for additional hardware on the post-production end of things. But we’re not there yet.

Here’s a simple breakdown of an HDR workflow. The camera should be capable of recording in a minimum 10-bit RAW format or even HLG natively. Nearly every digital cinema camera worth its salt records in one RAW format or another. Blackmagic shoots DNG. ARRI and RED have proprietary formats. The popular Panasonic GH series mirrorless cameras can record HLG.

In case RAW footage is a mystery to you, here’s an explanation. Instead of encoding the recording in a continuous video format, the image is recorded as a series of still frames. This is equivalent to shooting with a still camera in burst mode, but with very fast frame rates and very large images.

The single biggest advantage is the same reason why pro photographers always shoot in RAW. The camera does not process the image from the sensor but instead leaves it as a raw (hence the name) representation of what the camera saw. Your final output then has the greatest amount of latitude and flexibility in post-processing. The image is very flat, almost grayscale in some cases, but that allows you, the creative, to add back in the color and contrast that you want.

The biggest disadvantage to this type of shooting is having to deal with extraordinarily large file sizes and processing requirements in post. You will need a very fast rig for editing. Alternatively, you can use something like Premiere Pro’s auto-ingest transcoding to re-encode your RAW footage into intermediate files, which will make editing more tenable for older systems.

The RAW video will then be imported into an NLE capable of working with RAW footage and grading in the color space(s) required by HDR. Depending on your preferred post-production software, this could mean editing in one app and grading in another. All of the major NLEs currently support at least one form of HDR grading.

Since Dolby Vision is a proprietary format, it requires Dolby hardware, Dolby software, and Dolby metadata. Suffice to say, we’re going to leave the Dolby workflow out of this explanation. I believe if you have the resources to work in Dolby Vision, the company will send a team of people to teach you everything you need to know about working in its software.

One final note on how the various HDR standards differ. The processing and interpreting of the HDR signal is different. Some standards like Dolby Vision perform a scene-based analysis and utilize dynamic metadata to dictate how the image displays on final output. Others like HDR10 use static metadata. But HDR10+ offers dynamic metadata and analyzes by scene or even by frame, making it more comparable to Dolby Vision.

Getting Started

For my test workflow, I chose the Blackmagic DaVinci Resolve system. As previously mentioned, there are ways of generating HDR video in other software, but Resolve has been around longer than all of them and is a household name when it comes to color grading. Setting up the project and physical work environment is critical to working in HDR. If you’re already a color-conscious editor, you know the value and importance of having a properly lit workspace for grading. This is no different, but HDR did require some additional hardware in my case.

Here’s the good news: I managed to stretch my 2013 MacBook Pro’s lifespan a little longer and found that I could still work with HDR footage without it bogging down. (4K is another matter and another article altogether.)

What about cabling? I have an HDMI cable that is capable of handling full 4K resolutions, HDCP, up to 32 audio tracks, and a whopping 48-bit color. You may be thinking that this cable cost as much as a Vespa scooter, weighs as much, and is made of melted-down, solid gold, Jackson 5 records. You would be wrong. It was $11.99 on Amazon, and it handles HDR just fine.

Like me, you may have been spoiled for years by not needing any external video interface devices to display your content, but my setup for HDR work in Resolve required either a Blackmagic DeckLink 4K Extreme 12G or an UltraStudio 4K Extreme video interface. The DeckLink 12G is a PCIe card that takes HDMI from the computer and outputs an SDI or HDMI signal to an external HDR-capable monitor. The UltraStudio basically accomplishes the same task but with a Thunderbolt connection instead. There are other hardware options, but these are the two I considered for my workflow.

Most color-grading wizards will tend to wistfully mention a particular monitor that they favor, like the Sony PVM-X300. While this monitor is no longer available, it’s likely you wouldn’t have bought one anyway. At an estimated cost of $15,000 or more, it’s probably best to start with something a bit more economical. I went with a much less expensive ($5,499) SmallHD 24” HDR Production Monitor. While technically not a reference display designed for mastering, this 10-bit, 1080p LCD display offers 1,000 nits of brightness and is tough enough for location shooting or desk/VESA mounting. The video signal reaches the monitor via SDI, and the monitor requires only a bit of setup to properly display your HDR video. LUTs (Look Up Tables) can be utilized in the monitor itself for simulating a final image. And the proper HDR-compatible color space can be selected from the monitor’s menu.