DEFINITION September 2022 - Web


B etween low-energy lighting and virtual production, it’s fair to say that Isamu Akasaki, Hiroshi Amano and Shuji Nakamura’s late-eighties and early-nineties work on blue LEDs has brought a lot to film and TV. But as the proliferation of measurement standards suggests, it’s also provoked some complexity around how light and colour actually works. It’s tempting to assume that an LED video wall might be all the light a scene needs, given that the interactive play of light on real- world foreground objects is a large part of the appeal. That approach was used heavily for space scenes in Gravity , long before LED volumes for in-camera visual effects became popular. As Jeremy Hochman of Megapixel VR suggests, though, light cast by the screen is best used for its interactive properties only. Megapixel has built displays for high-end clients all over the world – both for conventional LED wall applications and some big-name, big-screen clients – using approaches that would become almost an industry standard. “In the virtual production space,” Hochman begins, “ First Man was the first to use an LED volume. It deployed a tile based around our team’s engineering specification,

along with our processing.” In the context of LED video walls, processing is the combination of rack-mount hardware and electronics in each panel, which bridges the device producing the video image and the LEDs themselves. Megapixel’s system, Helios, is designed with a lot of flexibility to synchronise timing and keep colour accurate. Still, no matter how good that processing is, colour performance is limited by the performance of the LEDs themselves, which are best not relied upon as a principal way to illuminate things – particularly people. “Colour quality in LED video walls works for dynamic lighting effects, but it’s not the best as a proper illumination device. Great, successful uses are for driving shots with bright neon, traffic lights and things like that – but RGB LEDs can’t properly mimic sunlight, or broad-spectrum illumination,” Hochman confirms. Megapixel has some new ideas in development around the concept of adding white emitters to LED display pixels. Emitters which use a blue LED to illuminate phosphor to create white or coloured light, generally produce a broader, smoother spectrum than those which don’t. Although, this is at a cost in efficiency and sheer

“Colour quality in LED video walls works for dynamic lighting effects, but it’s not the best proper illumination device”

81. SEPTEMBER 2022

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