Sports Imaging Forum: HDR Doesn’t Need To Wait for 4K/UHD
Vendors also agree that high frame rate can benefit more than just replays
While 4K continues to steal the headlines and hype in the television-entertainment industry, other formats — including 1080p and high dynamic range (HDR) — are pushing to stake their place in live sports production. Already in this month alone, impressive 4K productions have been HDR undertakings, including two HDR tests at the PGA Championship and the Rio Olympics.
It’s clear that sports-video production is at a crossroads in determining which aspects of image quality are most important and how they impact one another. That topic was core to a conversation on 4K, HDR, and high frame rate (HFR) at SVG’s Sports Imaging Forum last month.
With HDR gaining favor with sports broadcasters, technology vendors are echoing that sentiment, and, although many HDR tests are happening alongside an existing 4K production, many in the industry believe that the two don’t necessarily have to be linked.
“I’ve argued emphatically that we should absolutely not be waiting for 4K/UHD,” said Larry Thorpe, senior fellow, Imaging Technologies & Communications Group, Professional Engineering & Solutions Division, Canon U.S.A. “This time last year, we were in the SMPTE Study Group, and I was pleading for consideration of 1080p. I was surprised at the mixed views. However, I am ecstatic that, on [July 12], the ITU came out with a new standard, BT.2100. 1080p is internationally recognized as being worthy of HDR, and I think that’s wonderful because, on the consumer end, we still don’t know what the consumer can take in sustained viewing for hours in the home. We need to learn all that, do it on the back of something that’s closer to reality today. That’s 1080.”
There are also some challenges that remain when it comes to making those pixels in HFR sing properly in a sports environment. Dolby Laboratories has been showing HDR demos shot at 24 fps displaying motion artifacts, which are due to the fact that, at higher dynamic range, motion artifacts become more visible and color interactions take place during a pan of the image.
“The human contrast-sensitivity function at brighter absolute-light levels is much more sensitive to a change in luminance,” explained Patrick Griffis, VP, technology, Office of the CTO, Dolby Laboratories. “Hence, there are a lot more code values up there. That adds to this problem. When you have high-dynamic-range images, motion judder at any frame rate will become more apparent because the edges are sharper. So one argument for high dynamic range being paired with higher frame rate [is] to address that issue.”
Another key topic of the conversation was HFR and its place in sports production, where it has held a strong position as the preferred way to acquire slow-motion replays. However, those on the technological side see some potential for delivering HFR directly to the home, not just as a tool in an HD show. However, the challenge lies in compression: there are few to no solutions for providing a suitable compression system for HFR delivery.
“There’s nothing magical about having a compression system operating at higher frame rate,” said Hugo Gaggioni, CTO, Broadcast and Production Systems Division, Sony Electronics. “We capture 180 fps in compressed form in XAVC. Now, for distribution long term, that hasn’t been determined, but it’s because the standard doesn’t exist. There’s no physical barrier to do that.”
Added John Humphrey, VP, business development, Hitachi Kokusai Electronics America, “For a long time, we have been watching video where we don’t know what it’s been through. So, as long as customers sit, on average, 9 ft. from a 55- or 65-in. TV, I’m not sure how much difference it’s going to make.”
The panelists also addressed 4K and its relation to “data-rate gobbling,” referring to the fact that UHD requires 8X data rate before compression. Many find compression to still be a significant barrier to an enjoyable UHD experience in the home.
“One of the other things we have to pay attention to is the compression that’s being used; not just the resolution on the acquisition side but the compression on the distribution side has an impact on the quality of the image,” said Josh Limor, VP, technology and ecosystem development, Technicolor. “It can effectively make a 4K image look less resolved than an HD image, so it really becomes a trade-off as to how much compression — what your encoding efficiency is — vs. the resolution you are actually acquiring.