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When does 4K Resolution Matter?

You’ve probably heard a lot about 4K displays, but you might not know exactly what they are or why it’s important. The short answer is that 4K displays have approximately four thousand lines of vertical resolution (compared to approximately two thousand for HD displays). But what does it actually accomplish when more pixels are packed into the same amount of space?

Resolution, PPI, and Vision
The three things that make a difference in how you see an image or video on a screen are the resolution of the screen, the number of pixels in each inch on that screen, and your eyes. All of them affect your experience of the display in different ways.

Resolution is, quite simply, the sheer number of pixels – single points of color and light – that are used to make up the total image. Digital camera makers have been using the resolution of their cameras to indicate how sharp and detailed a picture will be in the millions of pixels, or megapixels. Standard definition televisions and VGA computer monitors had 480 lines of horizontal resolution (note, that since the aspect ratio changes the width, often the horizontal resolution is the only number considered). That works out to 307,200 pixels (or 0.3 megapixels). The move to DVD (720 lines) and then HD video (1080 lines) drastically increased the number of pixels (DVDs have 0.9 megapixels and HDTVs 2 megapixels). The Ultra-High Definition 4K displays have over 8 megapixels since they have four-times the resolution of HD displays.

While pixels are very important, anyone who has used a high-end digital camera can attest to the fact that a certain point you can’t see the difference. That’s due to the number of pixels that are fit into a certain space, or the pixels per inch (PPI). No matter what the display, if you get close enough to it, you’ll be able to see the individual pixels. The giant screen at Cowboys Stadium in Dallas has pixels that are 20mm in size (about ¾ inches), but because the crowd is so far away they can’t see the individual pixels. Your smartphone’s pixels are over 250 times smaller than the ones in Cowboys Stadium so you can view it from that much closer without perceiving the individual pixels.

Viewing Distance
The iPhone 6 came out with what Apple calls the “Retina Display” which basically means that the pixels are small enough that the human eye can’t distinguish them at a normal viewing distance. Images on the display look more real because you can’t see the edges of the pixels.

A 4K display makes it possible for you to be closer to the screen and for the screen to be bigger without you noticing any of the pixels that make it up. If you have a 28-inch monitor on your desk that’s running at Full HD (1080p) most people will be able to see the individual pixels at a viewing distance closer than four feet. But if you had a 4K UHD display, you could be as close as two feet without noticing the pixels (the average monitor is about 2.5 feet away).

From the other end of the spectrum, if you wanted to install a huge, 98-inch display you would need people to be at least 13 feet away before the pixels would disappear on a 1080p monitor, but with a 4K display they could be as close as 7 feet.

So it’s possible to have a much larger display in a smaller space without sacrificing the visual experience with 4K. When close viewing and large-screen displays are important, 4K is the ideal choice.