Video displays are everywhere, from cell phones to movie screens, and made of many different materials.
Increasing both the amount of pixels on the screen and the rate at which the pixels are refreshed has been a
continual process in the display industry, but there is a limit to how sharp and how quickly displayed an
image can be before the user will no longer notice improvement.
Table 1: Various display resolutions and their applications. 4K and 8K may vary somewhat
in horizontal
and vertical resolution due to multiple standards.
Larger, sharper displays require fitting more pixels on a screen at once. For the past decade,
high-definition screen resolution has been 1080, while movies are projected onto giant theater screens at 2K
resolution. However, 4K displays have started to make their way into homes as televisions or computer
monitors, and the forefront of resolution technology is 8K.
Figure 1: A comparison of screen resolutions for 8K UHD, 6K UHD, 5K UHD, 4K UHD, FHD and
SD. By Libron
(Own work) [CC0], via Wikimedia Commons.
Content: Keeping Pace?
Not a lot of content is available for the highest resolutions. Content is usually created in
ultra-high-definition (UHD) in order to make the visual effects and editing easier (they can zoom, crop, and
digitally correct errors and still make it look good when bouncing down to high-definition 2K or 1080p).
Until recently, 8K has been rare; used only in instances where heavy post-production is required. It’s also
used to digitize high-quality film prints, probably most famously with the 2012 scan of Lawrence of
Arabia1.
In June 2016, Guardians of the Galaxy Vol. 2 wrapped up production in 8K digital, the first feature
created in the emerging format, but a film in 8K is unlikely to ship to theaters as such.² Eventually
content will arrive for 4K, and 8K content will follow, but by then consumers may realize that increasing to
8K improves quality only for very large TVs; ones they may not realistically want in their living room. Note
that on the chart below³ one would have to be watching from a distance of 5 feet with a screen of ~90
inches to reach the limits of 4K, let alone 8K. For many, living room set ups and screen size preferences
ensure that 1080p is good enough. Nevertheless, 8K TVs may become commonplace soon enough, as technological
progress does not halt easily; however the march to higher resolution might end with 8K for the typical
home.
Figure 2: This chart shows that with an 84-inch screen, 4k resolution will only be
completely apparent
until a distance of about 5.5 feet or less from the screen. With a 55-inch screen, it’s 3.5 feet or
closer. Chart printed with permission by Carlton Bale from "Does Resolution Matter?"
Speeding up frame rates is another area where manufacturers push boundaries and standards. All LCD displays
have a certain refresh rate, measured in hertz (Hz), which determines the number of times per second the
screen can refresh its image. Frame rate, on the other hand, is the number of times an image is sent to the
screen to be displayed. Film has largely maintained a standard of 24 frames per second (fps), but directors
have experimented with higher. Peter Jackson famously shot his Hobbit films at 48 fps, which caused some
critics to accuse the film of possessing “the soap-opera effect,” where there’s less motion blur than
movie-goers are used to seeing on film.4 Modern LCD screens reduce motion blur using motion
interpolation, a smoothing technique that adds an extra frame in between frames by “guessing” what an
intermediate frame would look like and then inserting it, thus increasing the frame rate
artificially.5 This feature has had similar mixed reactions. Walk into any consumer electronics
store to witness the “uncanny valley-esque”
look of interpolated frame rates.
Gamers Get Real
One industry reaping great benefit from high frame rates is video gaming. Players are responding to visuals
on screen, so high frame rates feel smoother, but require much more computing power to render new images
rapidly, which is why console games have a capped frame rate while PC games allow adjustment based on
gamers’ hardware. For consoles, 30 fps is the standard, while 60 fps is considered optimal. Frame rates of
90 fps are used by Oculus Rift and HTC Vive, the current leaders in virtual reality hardware.6
When watching a movie, one is a passive observer to the action; but when playing a video game, one is
participating to a certain degree. Furthermore, when a person has a virtual world strapped to their face,
their brain, thinking that it is looking at the real-world, expects a refresh rate that responds to movement
in real-time. As such, inconsistencies with the frame rate have been blamed for causing motion
sickness.7 This is only a theory, however, since “virtual reality sickness” and how frame rate
correlates are unresolved and remain a highly-studied topic.
Faster processing means potentially faster render times and frame rates, but there’s a limit to how fast
humans can percieve frame rates. One could compare perception of frame rates with game performance; the
faster the figures on the screen are moving, the faster the image needs changing. In 2006, a study by
Claypool, Claypool, and Damaa tested players’ performances in a first-person shooter at different frame
rates. The study seems to conclude that the improvement in a player’s performance does not increase much
between 30 and 60 fps.8 Of course, this study was 10 years ago, so modern games with more
complicated graphics may affect the results of a study today. Many gamers would disagree with the spirit of
the study, in that frame rate is not only about performace but about “feel,” as well. One can achieve a
certain clarity that almost makes the game feel hyper-realistic and three-dimensional at times, which pairs
well with high resolution graphics. But although 60 fps seems like a good baseline for player performance
and feel, it ultimately comes down to each individual’s eyes.9 While there is a limit to how fast
human eyes can perceive a frame rate, each person is different. If we assume that most players start seeing
diminishing returns after 60 fps, which seems to be the case with many casual gamers, then display
manufacturers are relatively safe when it comes to refresh speeds.
Figure 3: The effects of frame rate and frame resolution on user performance. Score vs.
Framerate (512 x
384 resolution), Source: The Effects of Frame Rate and Resolution on Users Playing First Person Shooter
Games, Mark Claypool, Kajal Claypool and Feissal Damaa. 2006,
http://web.cs.wpi.edu/~claypool/papers/fr-rez/paper.pdf
On the forefront of display technology is 165 Hz and faster-refreshing 1080p monitors.10 Monitors
at 120 Hz used extrapolation to claim faster refresh capability, but cutting edge displays can finally
support the highest refresh rates. Faster monitors are always being developed, but today’s selection of
display technology can support incredibly smooth gameplay.
The next challenge is to make monitors that refresh at these fast speeds but also at higher resolution. 4K
screens require much more processing power and faster graphics cards to refresh a greater number of pixels
while synchronizing the incoming frame rate with the monitor refresh rate. This a matter of communications
bandwidth. Since incredible amounts of data need to be transferred to these screens at high speeds, for
bigger screens, innovative software and interface hardware are required to accomplish equally fast refresh
rates. DisplayPort is one audio/visual interface used for high resolution, high refresh rate transmissions,
currently supporting 8K at 30 Hz at its best.11
Where Will Display Tech Take Us Next?
Modern screens are already so sharp as to seem lifelike, and refresh rates are fast enough on
reasonably-sized screens for quick game rendering. Content may not yet be available to take full advantage
of the best displays, but it will come soon, and in great numbers. So, super high refresh rates on ultra
high resolution screens aside, where does the display industry go next? In spite of this “sensory wall” the
display industry is approaching, innovation will always soldier on. Maybe no one will care when 16K comes
along, but new paradigms will eventually revolutionalize display technology. Curved screens and backlighting
techniques can provide variation in LCD, OLED, and AMOLED markets. But TV networks, still catching their
breath after the upgrade to HD, are starting to roll out infrastructure to broadcast 4K content while internet streaming
services have slowly been adding 4K content as people buy compatible TVs.
Maybe vector-based graphics will leave pixelated displays in the past. With the rise of smart TVs, a consumer
might be watching a movie and have the iMDB page (an online resource for broadcast and celebrity content)
automatically show up on their tablet; an example of interactivity between entertainment devices in the
home. In a few years, don’t expect to be able to distinguish the leaps and bounds technology has delivered
within the pixels and smoothness of displays, but do expect something truly unexpected and novel to come
from the industry.
Benjamin Miller is
an Electrical Engineering junior at the University of Texas at Austin and Mouser's Technical Marketing
intern for the summer. He plays guitar with the Mansfield rock band MP3. During the school year he can be
found playing with electronics or doing homework outside of the Cactus Cafe, where he works as a doorman.
