Are Ultra HD Televisions Worth It? Study Works Out How Many Pixels Human Eyes Can Really See

They say “technology marches on,” but if we’re honest, that march has evolved into more of a sprint. Whatever you buy it’ll be mere minutes before a more up-to-date, faster, and higher-definition version is available, but is it worth it? After all, if you’re still using your humble human body to take it all in, can our sensory organs even keep up?

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A new study sought to explore this question with a specific focus on ultra-high-definition television (UHD TV). Production companies and TV manufacturers have been quick to jump on the novel technology, bringing you more pixels than you ever dreamed of (or really asked for).

4K and even 8K are now available to view at home, but would you notice the difference? Researchers at the University of Cambridge and Meta Reality Labs decided to find out by looking into the resolution limitations of the human eye, and what they found raises questions about whether all this new technology is really worth our hard-earned money.

The costs of UHD TV

“If you have more pixels in your display, it's less efficient, it costs more and it requires more processing power to drive it,” said study co-author Professor Rafał Mantiuk, from Cambridge’s Department of Computer Science and Technology, in a statement. “So, we wanted to know the point at which it makes no sense to further improve the resolution of the display.”

To do so, they set up an experiment that was a bit like those vision tests you do at the opticians using the wall chart of letters. Participants were then shown patterns with very fine gradations on a digital screen that moved closer towards them and further away.

Like getting someone to read all the letters on the bottom line, this meant they could ascertain what a TV actually looked like to a person based on where they were sitting. They then used this information to estimate how many individual pixels could fit into a one-degree slice of the participants’ field of vision – a metric they called pixels per degree (PPD). 

Is UHD TV worth it?

The results revealed that the participants' vision had a higher resolution limit than the old “20/20 vision” phrase would imply, but there are significant differences in that resolution when you break down an image into color vs. black-and-white. The average PPD for greyscale was 94, but this dropped off for red and green (89 PPD) and yellow and violet (53 PPD). That means, for most of us, UHD TV is probably giving us more than we can actually take in.

“Our brain doesn’t actually have the capacity to sense details in colour very well, which is why we saw a big drop-off for colour images, especially when viewed in peripheral vision,” said Mantiuk. “Our eyes are essentially sensors that aren’t all that great, but our brain processes that data into what it thinks we should be seeing.”

Now that we have this new approach to understanding what most people can really see, it can be used to inform manufacturers’ decisions so that they’re designing tech that will benefit the majority of the population rather than creating remarkable TVs for exceptional eyes (regrettably, as of yet, there’s not much of a market for snapping shrimp TV).

The study is published in the journal Nature Communications.