Smartphone screens are getting an upgrade—here are the specs to know about
Refresh rate? Touch sample rate? Color temperature? What’s the difference?
Yesterday, OnePlus announced its first true flagship phone. At $899 retail, the OnePlus 8 Pro packs just about every fancy piece of hardware you could want into a single Android phone. It boasts the most recent Qualcomm Snapdragon 865 processor, wireless charging, and a new four-camera array including an ultra-wide angle lens.
The real draw, however, is the screen. Last year’s OnePlus 7T got extremely high marks for its screen performance and the 90 Hz refresh rate—more on what that means in a moment—was a real differentiator for it. The 8 Pro ups the ante on display performance, but unless you’re fluent in these kinds of specs, understanding just what you’re getting for your money can be complicated. Here’s an overview of some screen technology terms and numbers that you’re likely going to be hearing about a lot more as 2020’s crop of new flagship smartphones makes their debut.
If you’ve ever noticed the weird soap opera effect on your TV or listened to Tom Cruise’s impassioned PSA, then you probably have a negative association with the term “motion smoothing.” With smartphones, however, things are different. The OnePlus 8 has a 120 Hz screen, which means that the picture you’re seeing refreshes 120 times every second.
On a smartphone, a higher refresh rate means that animations and scrolling happen more smoothly. If you have a typical 60 Hz phone, which includes the iPhone 11s, objects on-screen jutter a bit as they scroll by. You may not even notice it until you look at it directly compared to a higher hertz screen. Samsung has already equipped its Galaxy S20 with a 120 Hz screen (though, it won’t let you use both maximum resolution and refresh rate at the same time), and Google’s Pixel 4 has a 90 Hz display. More niche phones—specifically those meant for gaming like the Razer phone from two years ago—have been doing 120 Hz for a while.
While the numbers are relatively simple once you understand what they mean, the actual implementation isn’t always so straight forward. For instance, not all apps and content can crank out that many frames per second. In that case,some content will still lock the display into 60 Hz mode or allow the screen to add frames to the content in order to match its performance. If you really want to take advantage of the frame rates, high-end game apps typically provide the necessary frames per second to really notice a difference in smoothness.
The downside comes in the form of battery life. The screen is working harder, which draws more power. In order to address this, phones use different techniques like shifting down to 60 Hz mode when the screen isn’t actively moving, or in Samsung’s case, preventing users from maxing out on both resolution and refresh rate at the same time to limit the pure number of pixels the phone has to push all the time.
Touch sampling rate
Refresh rate isn’t the only place you’re going to see Hz used as a metric on smartphone screens. A metric called the display’s touch sampling rate determines how often it senses where you’re currently touching the screen. OnePlus’s new 8 Pro promises 240 Hz refresh rate, which means that 240 times per second, the display registers where your digit is making contact with it.
You’ll typically find that this number is double what the screen’s refresh rate is. iPhones, for example, have a 120 Hz touch sample rate to go with their 60 Hz display The Samsung Galaxy S20 has a 240 Hz touch sample rate to go with its 120 Hz display.
Simply put, the higher these numbers are, the smoother the on-screen movements will be. Again, adding to the touch sampling rate has a negative effect on battery life.
Before the war over refresh rates, smartphones battled over pure resolution. The sheer number of pixels on a screen could set it apart from its competition. Now, things have flattened out a bit in terms of pixel creep because it’s a game of diminishing returns. That’s due to the fact that the human eye can only resolve details to a certain level.
Apple ratcheted up the smartphone resolution competition with the iPhone 4, which introduced the Retina display. During the announcement, Steve Jobs explained that a 300 ppi device held roughly a foot away from your face would have pixels small enough to make text and graphics look as sharp as possible.
The OnePlus 8 Pro has a total resolution of 3168 x 1440, which is also known as 1440p or QHD+. On the Pro’s 6.78-inch screen, the pixels are plenty small for sharp graphics and text. Some phones, such as Sony’s Xperia Z Premium devices, reach higher on this metric to match the 4K resolution that’s now standard on most TVs, but that’s generally overkill and only costs you battery life without providing any real visual benefit.
And just because a phone can operate at a super-high resolution, doesn’t mean it always will. For instance, the Samsung Galaxy S20 will step down to FHD (1080p) resolution if you want to save power.
Measured in nits, brightness numbers are more notable on smartphone screens than they are on TVs. Typically, cranking the brightness of a TV is bad for its overall picture quality, but smartphones sometimes need the extra illuminating power to remain visible under bright conditions.
When most phone makers brag about their devices’ brightness, they use the peak brightness, which isn’t a number you should expect to experience on a regular basis. Generally, a higher number indicates a brighter phone.
OnePlus brags about a feature called Comfort Zone, which automatically adjusts the color of the display to match your surroundings and ambient light. Apple has a similar technology that it calls True Tone. The human eyes and brain do a great job making light we expect to be “white” look relatively consistent. In reality, however, different light sources—such as the sun and the overhead lights in your home—produce wildly different tones on the surfaces we’re looking at.
Color temperature addresses a unit of measurement called degrees kelvin. The lower the temperature, the warmer or more red the light will appear. The higher the temperature, the cooler or more blue it will look. The numbers are counterintuitive, but you’ve probably noticed the effect yourself. Your overhead lights may look nice and white, but when you open the shades to let in outside light, the bulbs suddenly look yellow or orange by comparison.
The same thing can happen with your screen. If its white point is set to match typical sunlight, but you’re sitting in a room with strong incandescent light (which registers as yellow), it may make your screen look too cool or blue. The phone automatically adjusts to try and make things look right.
If you have a modern flagship phone, the screen is already probably making this kind of adjustment since most of them leave it on by default. You may even notice it if you’re sitting in the sun and a cloud suddenly goes overhead—the screen may visibly change color.