8k knocking at the door in 2020

Sharp presented a 85″ 8K screen in 2015 at the bargain price of 125,000$. Assuming you were willing to shell that money you would not have any 8k content to display… Credit: Sharp

OK, we are just now getting used to 4K, 4k televisions are becoming more and more affordable, Netflix and YouTube are starting to have some good content choices and a few people are starting to talk about 8k!

In an interview with DPReview Yosuke Yamane, Division President of Panasonic Imagine Network Business Division, said that Panasonic is getting ready to the transition from 4k to 8k in 2020. The transition will be smooth, as it happened with the shift to HDTV and is now happening with 4k.

8k is the next step in video resolution, 4 times better than 4k, with 7680×4320 that is 33,177,600 pixel vs 8,294,40 of the 4k standard. Now, the crucial point is the definition of “better“. Numerically speaking 33 Mpixels is more than 8 Mpixels, but, as an example, 33 Mpixels eat up 4 times more space than 8 Mpixels, require more processing power, so they are not “better” in this sense.

I guess it would make sense to tie the “better” to our perception of quality, wouldn’t it?

Well, take a look at the graph of perceived quality, related to the possibility of a normal human eye to detect details (human eye resolution).

Plotting of human eye resolution against the current television screen resolution. Credit: Carlton Bay

In the graph you’ll see an upper part where our eyes would not be able to tell the difference in resolution among different screen resolutions. As you move farther away from the screen your eyes will see less and less details to the point that if the screen shows more or less details it would be indifferent to you.

Notice also that the bigger the screen and the more details your eyes can see, hence you will be perceiving them from greater distance from the screen. The reverse implication is that the smaller the screen and the less details can be seen by our eyes. This is because our eyes have an angular resolution of about 1 arcminute (that is 0.02°, or the capability to resolve -detect- a cube of 30 cm at a distance of 1 km, not bad…). The closer you get to a screen the less space of the screen falls under your eye, the farther away you are the more space is captured, hence more pixels can be resolved.

In the graph you see the plotting up to 4k but you will notice that the areas where a difference in quality is perceived is roughly the same. If you add an area below the 4k line, which would represent the perception of better quality for a 8k screen you’ll see that you will have to stay very close to a very large screen to appreciate an increase in quality.  Actually, if you have a 50″ screen you’ll need to watch it at a distance of less than 50cm to be able to spot any difference from a 4k!  And, of course, it may not be very comfortable to watch television from 30cm away.

Also, notice that once we add the area of quality improvement from our perceptual point of view there won’t be any more space left for a … 32k. This is because we have reached our eye maximum resolution.

In practice, as you can see from the graph, we have already reached this limit with 4k and, in most cases (normal distance when watching a television) this is almost reached with HDTV.

There are two factors, however, to consider. The first one is the quality of the image and the second is the feeling of “immersion”.

The quality of the image depends on the number of details shown (among other factors like contrast, rendering of blacks, luminosity, comet effects…) and the number of details is limited by the screen resolution but depends on the numbers of details that are transmitted. You can have a very high resolution screen (plenty of pixels) but if you transmit just few information you will have few details displayed. Now, unfortunately, this is what usually happens with television, because information is compressed during transmission by the coding scheme and this result in loss of information, aka loss of details. If you watch a soccer match and pay attention to the grass you will notice that it is blurred when the action is on, whilst you can see the single blade of grass when the action stops. This is because of the “intelligent” compression algorithm that knows that you won’t pay attention to the grass when an action is going on and compress the information about the grass more than the one about the players (where you are focussing on).  Hence, improving the transmission aiming at no-loss compression is doing a better job in improving quality than increasing resolution.

Second, you can tell the difference between watching a soccer game on a television or being at the stadium. What you miss when watching it on the television is the immersive sensation that you get at the stadium.   This is because your eyes keep roaming on a very large canvas and your brain register the space you are immersed in. This happens at home, but in this case, correctly, your brain detect an immersion in your home living room!  By sitting in front of a very large screen so that your angular vision is not able to cover the whole screen (the screen is larger than 130° from your viewpoint) you get this sort of immersive feeling. Hence an 8k television can support a very large screen, like covering the all wall of your living room. That will not provide you with more perceived “details” than a 4k screen but it will provide you with a sense of immersion and the experience will change completely (you cannot achieve that with a 4k screen, otherwise the image will get blurred).

For most of us, however, the 8k will remain, for most part of the next decade, a tribute to aggressive marketing, rather than a real benefit in improved experience.

About Roberto Saracco

Roberto Saracco fell in love with technology and its implications long time ago. His background is in math and computer science. Until April 2017 he led the EIT Digital Italian Node and then was head of the Industrial Doctoral School of EIT Digital up to September 2018. Previously, up to December 2011 he was the Director of the Telecom Italia Future Centre in Venice, looking at the interplay of technology evolution, economics and society. At the turn of the century he led a World Bank-Infodev project to stimulate entrepreneurship in Latin America. He is a senior member of IEEE where he leads the New Initiative Committee and co-chairs the Digital Reality Initiative. He is a member of the IEEE in 2050 Ad Hoc Committee. He teaches a Master course on Technology Forecasting and Market impact at the University of Trento. He has published over 100 papers in journals and magazines and 14 books.