HDR version image of the Eiffel Tower, Paris
High Dynamic Range (HDR) video is the next big thing facing the television industry. If HDR delivers as planned, it will bring a “pop” and “sizzle” to both high-definition and 4K video that any casual viewer can easily see. But HDR comes at a high cost that may slow it down.
Matthew Goldman, a self-described “geek,” is the president of SMPTE, the standards making body. In his day job, he is also senior vp of technology for television and media at Ericsson, where he is focused on video processing and media delivery solutions.
Matthew Goldman, president of SMPTE
Goldman has been actively involved in the development of digital television systems since 1992. He is a prominent participant in standards groups and his recent work includes HDR and Ultra HD technologies. Four of his projects have been recognized by Technology & Engineering Emmy Awards.
As an expert on HDR, The Broadcast Bridge’s Frank Beacham asked Goldman some basic questions about the technology in this interview.
The Broadcast Bridge: Matthew, give us an overview of exactly what is HDR.
Matthew Goldman: In all video displays, including those virtual reality headsets you wear, the dynamic range — meaning the difference in the contrast between the deepest blacks and brightest whites — have been grossly limited. The realism just isn’t there. Though our eyes can see and we can interpret a much wider range, why don’t we notice? Because we are used to watching television and have been conditioned to it for fifty years.
If you actually see the real scene next to the TV version of the scene, the real scene just pops out at you. The difference between darkness and brightness in that image on any of today’s displays is very limited. HDR will restore that ‘wowness’ to the television display.
Viewers will easily identify the image improvements provided by HDR, even in poorly lighted show rooms.
When we went from SD to HD to 4K is was for spacial resolution. But we didn't capture the dynamic range in that. There is no physiological reaction to dramatic scenes. HDR adds that. With HDR, you can simultaneously see images in both the dark and bright areas.
The Broadcast Bridge: Since HDR is separate from spacial resolution, does it work well with any resolution?
Matthew Goldman: Yes. It works just as well with HD as with 4K. It even works phenomenally well with SD. What happens is your brain interprets dynamic range as sharpness. It looks like the picture has more resolution. I can show you two pictures next to each other with the exact same number of pixels, but the one with standard dynamic range will look more drab, fuzzier and not as sharp. The other one will pop out at you. You will think one has much more resolution because it is so much sharper. But its not actually sharper, it has more dynamic range.
The Broadcast Bridge: I know you have been working on standards for HDR for a long time. Where does that stand and what will it take to implement the technology in today’s television infrastructure?
Matthew Goldman: By the end of 2017, there will be no technical reason we can't do HDR in every program being produced. The standards work is about finished. The remaining issues are all commercial.
The Broadcast Bridge: Let’s begin on the production side. What is needed to make HDR happen?
Matthew Goldman: In general, most television cameras manufactured in the past two years, though not designed for HDR, actually capture more dynamic range than can be used in current production. Until we came out with these new HDR standards, the dynamic range was the same since the 1930s. The peak white level was 100 nits — the common production format because that was the response level of a CRT display. Most newer cameras have the optics and most likely the sensor to go beyond the standard dynamic range, or SDR.
The imager and electronics of modern cameras are storing that high dynamic range information natively in the camera before it comes out. HDR comes into play in the transfer function. The light’s brightness values in the camera are converted to an electronic bit stream. At the display end, the opposite happens in the transfer function. HDR occurs in the transfer function. It’s not a post processing thing, though in certain major productions you can play with the levels in post. But the concept of HDR — the making of that contrast between the light and dark levels — is the transfer function in the camera and the display.
Of course, all the equipment in the production chain has to change to support HDR. Most new cameras are already HDR to one aspect or another. But most are not designed to HDR standards. Switchers must be changed or upgraded. Monitors also must be changed or upgraded. This is where it can get expensive.
The Broadcast Bridge: What about on the home display side?
Matthew Goldman: On the display side, there are several components combined to be what we call HDR. There are two HDR transfer functions. One of them is defined in SMPTE standard 2084 and its known as the perceptual quantizer, or PQ, for short. Another one is called hybrid log gamma, or HLG. (Developed by the BBC and NHK.) They are different but both are HDR. We add a wider color gamut to it and do it at 10 bits. Take those three together, the high dynamic range, the wider color gamut and the bit depth and we have HDR.
The basic level of HDR is known as HDR10. It uses the PQ transfer function plus the wide color gamut (ITU-R Rec.BT.2020) plus 10 bit sampling. That’s the baseline. Then they add to that static metadata that describes the reference display that was used that goes along with the coded signal. All Blu-ray discs support this. I think about every HDR display you buy today supports HDR10.
The Broadcast Bridge: Where does Dolby Vision fit in?
Matthew Goldman: Dolby Vision is one or four or five proprietary methods that that goes beyond HDR10. It uses the concept of dynamic metadata. Instead of being static all the way through, on a frame-by-frame basis, that metadata can change. It uses a proprietary Dolby remapping scheme they say offers a much superior HDR experience. Many of the TV receivers that come on the market this year will support both HDR10 and Dolby Vision and perhaps other systems. But not every manufacturer might do that.
Depending on how it was done in the display and how the original content was encoded, most people will get some, but not all of the processing, depending on the TV receiver they buy. These are commercial issues.
The Broadcast Bridge: OK, let’s cut to the chase. What will all this cost?
Matthew Goldman: Well, as I said, you will have to buy all new equipment for this. On the production side, it’s a new camera that is specifically designed for HDR. The production chain will need to be upgraded. You need new displays to display it. Virtually everything needs to be changed.
After this year, there will be no more technical issues, only commercial ones. Are you going to replace all your equipment at once or roll it out slowly? And when will there be a critical mass of the audience viewing HDR? Until then, you would have to simulcast to both audiences. Older shows can be post processed, but it’s not as good as actually capturing original HDR information.
HDR is a vision processing function. Every component doesn’t have to be taken out of the chain if you design something that can be upgraded with a new card. It is always possible, depending on the manufacturer.
Many pieces of technology in the broadcast and production suites will need to be updated to accommodate HDR. That includes T&M. Shown: Rohde & Schwarz VTx video test family, which provides a comprehensive and flexible test platform for HDMI 2.0a and HDR.
The Broadcast Bridge: When do you predict HDR will happen?
Matthew Goldman: It has already begun happening. If you go out and look now, there are tons of 4K HDR televisions with a decent size display for well under $500. If it’s not 2017, it will be 2018 on the consumer side. But not necessarily all those sets will have Dolby Vision — though some will. Some may have Technicolor of some other HDR scheme, but all will do HDR10.
On the broadcast side, which has sister standards, the cameras are already starting to roll out now. There are already HDR productions being done now. But another piece of that is when are they going to do live broadcasts with HDR? That’s a bit more complicated. We are already seeing HDR production of some premium content like sports in places like Canada.
This brings back an earlier question you asked about HDR being resolution independent. It should be noted that with HDR, there are no viewing distance limits as there are with standard 4K and HD sets in homes. Your eyes are so sensitive to brightness and darkness levels that you can see it from across the room. It offers viewers at home a much greater flexibility than with standard 4k TV sets.
If you are a broadcaster and don’t have the bandwidth for 4K — but you want the best gang for the bit — then HD requires a lot lower bandwidth. You might want to do 1080p 60 HDR Plus, which means HDR, plus wide color gamut plus 10 bit sampling.
If you transmit programming with 1080P, you are using much less bandwidth but the picture will look phenomenal. All of the TV sets out there — even the low-cost $200 models — upconvert lower resolution and do a great job of it. If the picture is progressively scanned, which 1080p is, and you use the TV’s built-in upconverter, you can watch 1080p programming on a 4K HDR set and it will look beautiful.
It will sizzle and pop — not because of the spacial resolution is artificially higher — but because of how the human eye responds to HDR. That ‘wowness’ factor will be there. That’s why a lot of broadcasters are looking at 1080p, HDR Plus as a transmission format even though there are no real 1080p displays that do HDR Plus.
The Broadcast Bridge: How does HDR work with future television technologies?
Matthew Goldman: HDR is ideal for ATSC 3.0. It’s perfect for any streaming over the internet. Netflix is already streaming 4K HDR10, one version of HDR Plus. Others are joining soon. Though some broadcasters will start rolling HDR out this year, before it becomes mainstream, it could be another two to five years. The standards are in place or will be in place before the end of this year. We are 95 percent complete right now.
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