Image enhancements include a perception of higher brightness and contrast, sharper edges, greater depth of field, and greater tonality, all of which combine to create a 3D-like effect.
The summit was held in New York City by the 8K Association to promote 8K to the content-creation community, content distributors (such as streaming services), and consumers.
More than 100 attendees also learned that:
• Streaming services will take the lead in bringing native 8K content to U.S. homes
• Native 8K content could be available for streaming as soon as 2020 or 2021, though it wasn’t clear if that timeline includes the U.S.
• Prices on large-screen 65- and 75-inch display panels will fall significantly because of Chinese-factory overcapacity, encouraging consumers to step up to larger screen sizes that best display moving 8K images
• Professional tools for capturing, encoding and decoding 8K images are becoming more readily available to content creators to support the launch of native 8K content, though availability is still limited and the products are still expensive
Super Sophisticated Upscaling
Although native 8K content isn’t yet available in the U.S. through broadband streaming services or through cable- and satellite-TV providers, TV makers have incorporated increasingly sophisticated algorithms in their 8K TVs to upscale SD, HD, and 4K UHD content to 8K resolution.
The new algorithms are “incredible,” said Chris Chinnock, executive director of the 8K Association. A Samsung executive noted that all Samsung 8K TVs use machine learning to sharpen edges, create texture, and reduce video noise while reducing such artifacts as banding.
Mauricio Alvarez-Mesa, CEO of Spin Digital.
The Distribution Challenge
A major challenge to delivering native 8K content to U.S. consumers, however, is the need for a more efficient video-compression codec to replace the current widely used HEVC codec, said Mauricio Alvarez-Mesa, CEO of Spin Digital, a maker of video encoders and players.
Native 8K content features four times the pixels of a 4K image’s 8.3 million, and the ability to push more 8K content through the same pipe would encourage broad 8K adoption by service providers. The first 8K streaming services, however, will use HEVC, Alvarez-Mesa said.
For 8K streaming to take off in the U.S., households must also connect to fatter broadband pipes and faster Wi-Fi networks that many homes lack, Alvarez-Mesa added. “We really need faster connections.”
The 8K Advantage
To stimulate 8K adoption, everyone from content creators to consumers must be convinced that 8K makes a visible difference at typical viewing distances, presenters said.
To that end, YungKyung Park, associate professor of the College of Art & Design at Ewha Womens University in Seoul, presented the results of a study in which 120 observers said they saw visible improvements in 8K images and videos over their 4K counterparts on separate 65-inch TVs positioned side by side. The observers viewed the TVs at a distance of 9 feet in dark rooms that simulated nighttime viewing conditions.
For all images and videos, 8K performance was rated 35% higher overall. Perceived image quality increased 30% over 4K, and depth perception increased 60%, according to the study.
Each TV was calibrated at 500 nits of peak brightness. All observers had 20/20 vision and normal color vision, and all were shown the same 16 static images and same three videos on both screens.
Park also pointed out that the 8K videos and images that showed the greatest improvement contained objects or people at the front of the scene and in the center of the screen.
8K’s “hyper-realistic” images are four times denser than 4K images, creating the “illusion” of higher brightness, higher black-and-white and color contrast, and sharper edges, all attributes that capture an object’s 3D information. Viewers perceive an “illusion of depth” that can’t be measured, Park explained. “With 8K, expect hyper-realness.”
Video-services consultant Florian Friedrich of FF Pictures said 8K “makes pixels disappear as much as possible” along with digital artifacts such as flickering, thus creating an “analog look.”
Director and cinematographer Phil Holland told the audience that 8K displays create a “quicker level of immersion” and likened them to digital windows that don’t show “digital fingerprints.”
The level of detail in 8K content gives consumers “a reason to rewatch [a program] and discover new stuff in a frame,” he added. In extra-wide shots, 8K makes even small people visible, and in nature images, 8K delivers nature’s subtle textures, with a leaf’s surface looking almost like a reptile’s skin in extreme closeups.
Ideal Viewing Distance
You’ll be able to discern the benefits of 8K without having to sit within 2 feet of a 65-inch screen or use binoculars from a typical viewing distance in the home, said Friedrich of FF Pictures.
To determine the ideal on-axis viewing distance (sweet spot) from a 16:9 8K TV, multiply the screen’s height by 2.5, he advised. For a 65-inch TV, the sweet spot is 6.6 feet from the screen. For a 75-inch TV, the ideal distance is 7.7 feet, and for an 85-inch TV, it’s 8.7 feet Friedrich said. At these distances, consumers will enjoy an ideal 45-degree field of view (FOV) to the TV.
He described distances of 2X and 3X a screen’s height as “good.” (See illustration below.) At twice the height of a 65-inch 16:9 8K TV, the viewing distance would be 5.3 feet, and for a 75-inch TV, it would be 6.1 feet.
At three times the height of a 65-inch 16:9 8K TV, the viewing distance would be 8 feet, and at three times the height of a 75-inch screen, the viewing distance would be 9.2 feet.
Another benefit is visible even if you’re sitting farther away: the elimination of aliasing (or flickering) of diagonal lines and diagonal edges, Friedrich said.
Codecs to Come
To deliver the benefits to homes, HEVC is “right for now,” but more efficient codecs such as VVC (Versatile Video Coding, or H.266) are needed to stimulate native 8K content distribution to U.S. homes, said Spin Digital’s Alvarez-Mesa.
HEVC is “right for now” because it is already widely adopted and available in most TVs, 8K HEVC encoding tools are available for content creation, and 8K HEVC decoders are available in chips for consumer products.
VVC, on the other hand, is still in development with a targeted 50% greater bandwidth efficiency compared to HEVC with the same subjective quality as HEVC. So far, however, the codec has achieved 37% greater efficiency at its current stage of development, Alvarez-Mesa said. Although a final standard is expected to be approved in July 2020, initial implementations aren’t expected to hit the 50% target, he added.
Higher broadband and home Wi-Fi speeds are also needed. A single 8K HEVC stream requires a minimum average bit rate of 84Mbps, Alvarez-Mesa explained. In contrast, the average fixed-broadband download speed in the U.S. was 95.25Mbps in the second and third quarters of 2018, based on consumer-initiated tests made through the Speedtest mobile-phone app, network-testing company Ookla said on its web site.
For streaming services such as Netflix, a more efficient codec other than HEVC is necessary “if the cost of Internet bandwidth remains the same for the next few years,” Alvarez-Mesa said.
A robust rollout of 5G fixed-wireless services that could replace wired broadband to the home would also help stimulate 8K programming by streaming services, given download speeds of 200Mbps and up.
For satellite TV companies, a single high-quality 8K HEVC program uses up the same amount of bandwidth as four 4K channels or 16 HD channels, and if the service provider compresses the 8K signal a lot, “you lose the 8K effect,” Alvarez-Mesa said.
As for adoption by local TV stations, next-generation TV broadcasts based on the fledgling ATSC 3.0 standard will have the bandwidth to support 4K but not 8K, Alvarez-Mesa said. TV broadcasters have promised that by the end of 2020 TV stations in 40 markets will deliver next-generation ATSC 3.0 TV signals to compatible TVs connected to indoor and outdoor TV antennas.