Expanding the color gamut of UHD was hot topic. Much as already been said about the gamut known as Rec.2020, which encompasses a significantly wider range of colors than HDTV's Rec.709 and even the digital-cinema P3 gamut. (Actually, color gamut is only one part of Rec.2020, which is more formally known as ITU-R Recommendation BT.2020 and also includes parameters such as display resolution, frame rate, color bit depth, and color subsampling.)

Some presenters advocated going much farther by using the XYZ color gamut, which extends well beyond the entire range of colors visible to the human eye. By using XYZ, the system would be entirely future-proof, accommodating any display technology that might be developed without having to create a new system all over again.

Frame rate was also debated. Of course, higher frame rates result in sharper motion detail, especially if the camera's shutter aperture—the fraction of the entire frame duration that the shutter is open—is low. (The longer the shutter is open during each frame, the blurrier moving objects appear.) However, a low shutter aperture also increases visible judder, a stuttering in what should be smooth motion. Also, higher frame rates look less like film and more like video, which many cinephiles object to. Still, many presenters said, in effect, "Get over it, this is the future we're talking about!"

Richard Salmon of the BBC brought some demo material comparing standard and high video frame rates—50 vs. 100 frames per second for Europe and 60 vs. 120 fps for the US. In the European clips, the 50 fps material was shot with a 50% shutter aperture, while the 100 fps footage was shot with a 33% aperture; in the American clips, both 60 and 120 fps were shot with a 50% aperture. In all but one case, the objects in motion were much sharper at the higher frame rate, and I did not see any judder. The only exception was a side shot of a woman juggling three bowling pins, and in that case, there was no improvement in the motion sharpness because, we were told, the human visual system cannot resolve rotating motion very well.

HDMI 2.0 was mentioned by Peter Putman, a well-known industry analyst and journalist whose presentation focused on the consumer-display side of the equation. According to his calculations based on using the RGB color space, HDMI 2.0 with 18 Gbps of available bandwidth can convey UHD at 60 fps with 8-bit color but not 10-bit, while DisplayPort 1.2 with 21.6 Gbps of bandwidth can handle 2160p/60 with 10-bit color using RGB coding.

Most of the presenters advocated for UHD to adopt the entire Rec.2020 suite of parameters, including a resolution of 3840x2160, the specified color gamut (if not XYZ), frame rates up to 120 fps, at least 10-bit color (preferably 12-bit), and 4:2:2 subsampling (if not 4:4:4). However, HDMI 2.0 at 18 Gbps can't accommodate all these upgrades, so we face a dilemma—increase HDMI 2.0's data rate, abandon HDMI for DisplayPort, or accept lower standards for UHD.

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