Calibration Expert: `Is 10,000 Nits Of Brightness Enough?’
Although some experts have warned against going too far with peak luminance in next-generation televisions designs, Tyler Pruitt, technical evangelist with display calibration specialist Portrait Displays/SpectraCal and a SMPTE member, said existing standards aren’t nearly high enough.
Speaking at the Insight Media/Samsung-sponsored QLED and other Advanced Display Technology Summit in Los Angeles last month, Pruitt said that many have balked at Dolby’s 4,000 nit aspirational brightness levels for displays, warning that specular highlights would be blinding to audiences watching in dark rooms. But Sony demonstrated at CES 2018 that 10,000 nits “might not be high enough,” at least not for professional cinemas.
“Sony had a demo at CES that pretty much put to bed the notion that 10,000 nits was going to require sunglasses,” Pruitt told the gathering of content grading and production professionals. “They played pretty much the same image on their 2,000-nit Z9D and an 85-inch 8K prototype display and it made the Z9D picture look like SDR. It was in a dark room. It didn’t make your eyes hurt, and it made images look like they were right in front of you.”
Pruitt said Sony’s demo “proved that 10,000 nits isn’t anything to be afraid of. We should embrace it and raises the question, `Is 10,000 nits enough?’
“I think SMPTE should start looking at ST.2084 and making the peak brightness limits go higher,” Pruitt said. “This is supposed to be an aspirational spec, like ST.2020, that people can working on and prepare for the next 10 years. But [the technology] is coming faster and faster than I think anyone expected.”
“We want to have the aspirational specs always be farther along than the current technology,” Pruitt said.
As for the technology approaches most likely to get there, Pruitt pointed to new direct LED (like MicroLED) as a logical candidate. Samsung has said it plans to introduce one of the first consumer MicroLED displays, which it calls The Wall, later this year. The 4K screen will measure 146-inches.
But before 10,000 nit displays come to the living room, Hollywood studios and post-production facilities will have to get up to speed first. Currently, the brightest production monitor used for color grading is Dolby’s Pulsar 1080p display, which achieves HDR. But the most commonly used monitor is Sony’s X300 32-inch 4K RGB OLED, which doesn’t get much above 1,000 nits.
“There are a couple of other new kids on the block, which are all LCD-based,” Pruitt observed. “Flanders and TV Logic are using the same panel. Flanders is upgrading theirs to 3,000 nits vs 2,000 nits for TV Logic. Both are DCI 4K resolution and use a zone backlighting system with 2048 zones in a 31-inch screen size. Most TV manufacturers peak at 500 to 600 zone for a 65-inch TV, and we are talking about 2048 zones on these 31-inch monitors.”
The problem with using a 31-inch hero monitor in the mastering suite, he said, is that when “the bill payers” come in the room, they want to sit back on a comfortable lounge chair in the back of the room and watch on a larger screen that they can see from their perspective.
For this, larger displays, typically based on plasma or OLED, are now brought into the suite. The big screen display, which is typically unable to achieve the same look as the hero monitor, must be perceptually tuned (not calibrated) to look like the monitor, with unavoidable differences, particularly in D65 white point, as a result.
“One of the biggest problems people are having is when you have the reference monitor and the client monitor in the same room. These perceptual differences are subtle unless you have the monitors together in the same room. You’d be hard pressed to go from one room to another and remember exactly what that white looked like. The human visual system is very good at adapting to white points,” Pruitt said.
But when the displays are side-by-side in the grading suite distinct shifts to red or green can be seen. Pruitt said, typically one of “the bill payers” will say they want the picture to like it does on this monitor and another scene to look the way it does on the other monitor, forcing dilemmas and headaches.
“We have to have one mastering monitor that is the hero monitor,” Pruitt declared.
“What I am thinking is once we can actually make a large mastering HDR monitor, we will have only one monitor in the suite and everyone will look at it and we won’t have this discrepancy,” Pruitt said. “My single monitor Utopia is a minimum of 4,000 nits at 55 inches in 4K resolution. If we get to that we can have one monitor in the room and there is no point in having a small monitor. Based on prototypes I have seen or heard about, we are not too far away from that.”
By Greg Tarr
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