The color grading suite at Light Iron in Hollywood uses a Sony BVM-X300 OLED HDR 4K professional reference monitor for grading.
If UHD is going to become a mainstream broadcast medium, we’ll need to be able to monitor, edit and review it. But can we?
In the first two parts of this series (Part 1 and Part 2) investigating the challenges posed by the advent of UHD delivery to the home we’ve looked at how a major west coast post house, AlphaDogs deals with finishing projects developed for this new medium. Then we heard about considerations when dealing with the signal itself from the perspective of one of the major systems manufacturers, Adobe.
This time we’ll delve into some of the most significant post production equipment designed to help editors solve the dilemma posed by UHD.
How to Monitor It?
Step one would be to find a critical evaluation monitor that can display all aspects of UHD, and much to my surprise, that doesn’t yet exist.
Even mighty Sony, to whom we have traditionally turned for the evaluation-quality screens in top hero suite editing and color grading bays, has yet to completely fill the bill.
“We at Sony feel that UHD is fairly well defined, but the problem is there are so many flavors of it,” began Gary Mandle, senior product manager for direct view displays at Sony during our one-on-one interview. “That’s especially true when it comes to High Dynamic Range. In the cinema market, the HDR format of choice for Digital Cinema Packages (DCP) seems to be Dolby Vision, which is an expansion of Perceptual Quantizer (PQ), which was published by SMPTE as SMPTE ST 2084. But the broadcast version we call UHD still has a lot more versions of HDR competing for acceptance.”
One of those contenders that Mandle finds has advantages is Hybrid Log-Gamma (HLG) developed by the BBC and NHK which has significant benefits for live broadcasts. HLG is not dependent on metadata and is compatible with both SDR displays and HDR displays, and is supported in Rec. 2100.
However, here is where a crack is exposed in the UHD format crystal ball.
Rec. 2100 utilizes the colorimetry specified in ITU-R Recommendation BT.2020, the color space intended for the UHD signal.
Mandle verifies that there is currently no reference-grade monitor, no matter how expensive, that can accurately display the full 2020 color space.
Sony’s BVM-X300 OLED master monitor boasts a second 3G/HD-SDI 4K input for simpler system integration.
That includes Sony’s flagship BVM-X300 30-inch 4K OLED master monitor.
“It would be kind of like putting 1,000 horsepower into a Mini Cooper,” he explains. “You might be able to do it, but you couldn’t really use it.”
The way he describes the situation, this is because Rec. 2020 was originally designed around lasers which have single frequency primary colors.
The effect of perceiving various hues from the stimulus effects of color on the three cone cells is called Tristimulus. But at the level of Rec. 2020, it's not the same for everybody. Click to enlarge.
“Because of this, you run into what is called ‘metamerics’,” Mandle said. “That is the phenomenon that since the human eye has three color receptors, or cone cells, so depending on the saturation of the light different people will perceive different colors. When you get to as high a gamut as Rec. 2020 you have reached the perceptual edge of human visual acuity.”
To achieve the wider gamut of Rec. 2020 the display needs to utilize single frequencies for the primary colors. That means there will be spikes of color information separated by low imagery levels.
Rec. 709 did not suffer this phenomenon, but to achieve the true wider gamut of Rec. 2020 you would get to the point where two people looking at the same picture would actually see different colors.
“We do make settings in our monitor that will adjust for hue shifts,” Mandle said. “And we can definitely show P3 and Adobe RGB color space but we can’t get the actual primaries to go all the way out to the reaches of Rec. 2020.”
A solution post houses have come up with is to grade for P3 which has a much narrower color gamut, and then encode the signal for Rec. 2020.
How to Cut It?
Fortunately, our industry’s most popular NLE for prime time productions, the Avid Media Composer, is already up for the UHD challenge.
‘For Avid’s purposes, there is little difference between 4K and UHD,” David Colantuoni, senior director, product management, creative tools & storage | products and technology at Avid, told me. “It really just depends on how a production is output.”
Avid's MediaComposer/Symphony User Interface.
Because they have been resolution independent for a long time, systems like Media Composer for editing, Nexis storage and Maestro graphics have been able to handle file sizes even larger than UHD for years.
“At IBC we also announced we are getting into the video server realm with FastServe,” Colantuoni said, “which can also handle UHD and 4K delivery.”
One of Avid’s important empowering technologies is their DNxHR (Digital Nonlinear Extensible High Resolution) codec for UHD which was announced at IBC 2014.
Even HDR is not a hindrance.
“We support close to all of the different HDR profiles,” Colantuoni said. “We just need to add the latest version to our HDR color profile and our systems can handle it. Even Dolby Vision doesn’t require a lot of coding for us.”
Actually, Avid is already looking beyond UHD and 4K. Last December the company announced 8K project presets inside Media Composer.
Colantuoni told me Avid was part of the ATSC 3.0 process, so they fully support it. “It’s a way for the industry to move forward to next generation television,” he said, “and we are completely behind it.”
View and Review
As reported in Part 1 of this series, UHD adoption has been more robust in Europe than in the States. One of Spain’s leading NLE manufacturers, SGO, has taken a unique approach to helping facilitate its post production.
SGO’s powerful Mistika edit and finishing system gained acclaim during the era of 3D when its massive processing power was needed to handle the large files that format still requires.
Mistika VR is one of the first of the separate modules of the Mistika Ultima hero suite to be released.
But last year they decided to market the individual modules of Mistika separately. The first manifestation of this was Mistika VR, seen at IBC 2017. Mistika VR provides3D stabilization and stitching together of the equirectilinear video elements for immersive 360° Virtual Reality productions.
I’ve been told that we should expect Mistika Color by the end of the year with other components to follow. Eventually clients will be able to re-assemble all of the modules together to re-form the Mistika Ultima hero suite.
At this year’s The NAB Show, SGO will be giving us Mistika Review for UHD production, a system that will allow every member of the production chain to view, review and comment on segments of a UHD project from anywhere in the world.
As Francisco Ramos, product liaison and Mistika specialist with the SGO development team, told me during an interview from Madrid, “The editor may be in Hollywood, the colorist in London and the producers in Rome. With Mistika Review each will be able to see and give feedback on UHD scenes in real time on any platform (Windows, Mac and Linux Centos version 7) that is connected to the Internet.”
So UHD is real, and its challenges are going to be with us for a long time. That’s OK. Post production, as usual, can handle it.
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