One selling point for smartphones and mobile devices is the resolution of the screen. The higher the resolution, the richer the image being displayed. A high-resolution display can come in handy for entrepreneurs on-the-go, when they need to review projects on their phones or share creative materials with clients while on the road.

But at what point does too much resolution become, well, too much? For example, Chinese smartphone manufacturer Oppo recently launched its new flagship smartphone -- the Find 7. The device features a ridiculously high-resolution “2K” display.

For the uninitiated, this means the Find 7's display will have a 2560 x 1440 resolution, or half of the Ultra High-Definition “4K” standard. Sounds amazing, right? But do you really need that many pixels on your smartphone?

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When Apple introduced the iPhone 4 in 2010, the company coined a clever new marketing term to describe the device’s high-resolution screen: Retina display. Apple's claim was that the display packed as many pixels per square inch as the human eye was capable of discerning from a standard viewing distance. For a smartphone viewed at 8 inches, Apple said the magic number was 300 pixels per inch (ppi). The iPhone 4 boasted a 3.5-inch, 960 x 640 screen -- good for a 326 ppi density. Apple said anything more would be overkill.

Almost four years later Apple still stands by its Retina-based claims. While the displays on the current generation iPhone 5C and 5S have increased in size to 4 inches, their ppi holds at 326.

Competitors have pressed beyond the Apple-defined limits of the human eye, however. Last year’s flagship phones from HTC, LG, Samsung and others sport full 1080p (1920 x 1080) displays with pixel densities well above 400 ppi. And then there’s Oppo’s Find 7 at 2,000.

The Find 7 features a massive 5.5-inch display with a full “2K” resolution of 2560 x 1440 pixels. That works out to a stunning 538 ppi. And -- get this -- the Find 7 actually isn’t the first 2K smartphone to launch. Lesser-known Chinese company Vivo’s Xplay 3S was introduced last December sporting a 6-inch 2K display with 490 pixels per inch.

That’s still well beyond mere Retina territory.

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But does packing that many pixels into a smartphone even make a difference? Larger displays need higher resolutions to look sharp. In the same way that a 70-inch flat panel TV looks terrible when you play standard definition content on it, a 6-inch smartphone won’t look so hot running at lower resolutions like 720p. And as Apple said, viewing distance matters: The closer you hold your phone to your eyes, the more readily you’ll be able to discern individual pixels. So if you’re drawn to larger screens and tend to hold them quite close to your face, you’ll want a phone with a high ppi.

Here’s the rub: All of this is mostly moot unless you have 20/20 vision or darn near it. And pushing more pixels is greater strain on a device’s processor and battery. So that 2K display had better be backed by a smartphone that's packing a serious CPU and a giant battery to keep it running. As with most things in life, the law of diminishing returns applies to smartphone screens: A 2K display is useless if the battery powering it has run dead.

This might be why industry giant Samsung disappointed some hardcore fans when it revealed its new flagship model late last month. The Galaxy S5 “only” sports a 1080p resolution, not the 2K panel some were hoping for. Maybe Samsung decided enough was enough and opted for battery life over pixel count. For now, anyway.

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