Have you ever had a tough time watching a movie on a tablet on a bright sunny day? Or spent a lot of time slightly adjusting the angle of your laptop screen at work? Any time you find yourself changing the angle of your screen or the screen brightness, it's probably because the devices in your life have screens that have trouble dealing with the ambient light wherever you are.
But it's light, right? Light is everywhere, so why are your devices struggling? That light is everywhere in the outdoors is exactly the problem. You know how, when you emerge from a darkened movie theater, any kind of daylight seems blinding by comparison? It's the same thing with your portable devices.
When you walk outside, your eyes are flooded with light from the sun. Now, looking down at your phone in the sunlight, the screen seems dimmer than it was inside, even though the brightness hasn't changed at all. To compete with the sun, you now have to really increase the screen brightness, otherwise it looks too washed out.
Another problem is screen's shiny, reflective surface. Basically, the shinier your screen is, the more likely a reflection from a light source will completely obscure the content on your tablet. However, the most basic Amazon Kindle, a favorite of bookworm beach-goers, is really easy to read in the sun. Why? The Kindle counters the main difficulty with the human eye and the sun by emitting little to no light and having a matte (non-reflective) screen.
Why does having a shiny screen or low screen brightness hurt your screen visibility when you're outside? For more details, read on.
When creating the screen for a device, be it a phone, a laptop, or a TV, the manufacturer has to walk the line between "clear enough to see through" and "not so shiny that bright light makes it impossible to see through." The difficulty lies in the fact that these two goals directly contradict one another.
To be clear enough to see through, the screen has to be free of imperfections and shiny. Otherwise, it would be like trying to look through a pane of glass that's been abraded with sandpaper, and the surface would become opaque. On the other hand, light strongly reflects off of smooth, shiny surfaces, sometimes to the point when it's impossible to see beyond the screen (similar to having all the lights on in your house, and trying to look outside at night).
Another compromise has to be made if the screen is a touchscreen; imagine playing Angry Birds on a screen that was as rough as a piece of paper! At the end of the day, the consumer's comfort comes first; no one's going to buy a phone with a rough surface that wears down your fingertips.
This is why smartphones and tablets have the shiniest screens: we need to touch their surfaces to operate them. Unfortunately, that shiny surface becomes problematic when you want to watch something outside in the summer sun. You'll probably have to lie on your back, with the tablet creating its own shade. Even then, the picture's not great.
Laptops without a touchscreen have screens that are less likely to produce a strong glare, but it still happens. Thanks to the portable nature of laptops, they have to be somewhat usable in the outdoors or other places with strong lighting (i.e. the office). However, the screens still have to be clear and shiny enough to see through. (Kindles are the exception to this; in addition to having matte screens, they also do not emit light that has to compete with ambient daylight.)
Televisions, on the other hand, generally do not have touchscreens, are not portable, but still need to be transparent. It turns out that TV screens are the least reflective of the three devices. This is a somewhat recent development; TVs in the 80s and 90s were often huge boxes with very shiny screens.
Back then, to manufacturers, TVs were meant to be viewed in a darkened room, so a highly reflective screen wouldn't bother anyone. However, in real life, we don't just watch TV indoors at night with the lights out.
Reacting to consumer complaints about glare, the industry took steps to improve the viewing experience by introducing matte screens that reduced glare at any time of day. Generally, if you look at a reflection on a blank TV screen, it'll look much fuzzier than the reflections in a laptop screen and a smartphone screen.
The matte screen finish is not quite as smooth as the other screens, and instead of directly reflecting the light back into your eye, it sends the light in all different directions, reducing the glare while still enabling the viewer to see the content on the screen. Even though your TV screen is the least reflective, taking your TV outside would not improve your viewing experience, as you'll see.
Black levels and peak brightness
The other part of screen visibility is how bright or dim a screen can get. There is an upper and a lower limit to the amount of light a screen can produce. The “black level” is the minimum amount of light emitted from a screen while it is rendering a black image. “Peak brightness” is the maximum amount of light emitted from a screen rendering a white image. The luminance of the emitted light is measured in nits, where a higher number of nits indicates a brighter screen, and a number closer to zero nits indicates better black levels.
While the terms “black level” and “peak brightness” are usually referring to TVs, they can be equally applied to any device with a screen, such as a smartphone or a laptop. Smartphone and laptop manufacturers are starting to deploy the technology developed for flagship televisions on smaller screens.
An ideal screen would have extremely dark black levels and extremely high peak brightness values. Darker black levels means that a screen can bring darker scenes with more subtle shading to life, rather than just looking flat and unrealistic. Higher peak brightness levels means that scenes can appear as vivid as they do in real life.
The black level and the peak brightness values are indications of what is technically achievable by a given screen; in reality, those values change when content plays on a screen because the black and white shades intermingle and cause the darker shades to brighten and the brighter shades to dim.
To get an idea of the current scale of the black level and the peak brightness, the UHD Alliance has set the goals that need to be reached by televisions, laptops, and smartphones in order for them to achieve the coveted Ultra HD Premium certification:
EITHER black level ≤ 0.05 nits and peak brightness ≥ 1000 nits
OR black level ≤ 0.0005 nits and peak brightness ≥ 540 nits
EITHER black level ≤ 0.1 nits and peak brightness ≥ 600 nits
OR black level ≤ 0.0005 nits and peak brightness ≥ 540 nits
black level ≤ 0.0005 nits and peak brightness ≥ 540 nits
For televisions and laptops, there are two different sets of black level and peak brightness values because with the technology as it is now, it’s very difficult to achieve both very dark black levels and very high peak brightness levels. One standard favors dark black levels (black level ≤ 0.0005) and the other favorites high peak brightness levels (peak brightness ≥ 600 nits).
In time, new technologies may push these limits to even further extremes, but for now, these are the goals that manufacturers are working towards. For comparison, the most basic TVs, like the one in your friend’s dorm room, have black levels of ~0.1 nits, and peak brightness levels of 100-200 nits.
So now that we know what black level and peak brightness values manufacturers are working towards, let’s see what they’re actually doing. Below is a chart of the black level and peak brightness data we’ve collected from all of the smartphones, laptops, and televisions (separated by OLED and LED-LCD) that we’ve tested recently.
In general, these trends reflect the viewing atmosphere of each of the three product types. Televisions, while also built to function in broad daylight, are still trying to closely replicate a darkened movie theater experience. TVs don't have to be very bright to seem bright in a darkened room, but they have to make a special effort to emphasize the subtle shadows of a darker scene, so that they are not wiped out by brighter highlights. However, that means that most TVs are really not suitable to be viewed outside in broad daylight; the ambient light will completely wash out both the darker tones and the brighter highlights.
Most of the TVs we've tested are much more focused on having darker black levels than higher peak brightness levels. OLED technology is at the frontier of darker black levels in TV panels.
Laptops are much more portable than televisions. To deal with the possibility of brighter ambient lighting conditions, the peak brightness of a laptop screen is often boosted so that bright images are preserved and not washed out by the fluorescent bulbs above your workstation. Increasing the peak brightness often washes out darker scenes, so darker black levels are not really a priority for most laptops.
Bucking the trend, however, are laptops and tablets that are starting to incorporate AMOLED screens (basically, slightly improved OLED technology). In the zoomed-in version of the chart, you can see two laptops are approaching OLED TV black levels; those two laptops have AMOLED screens.
Strangely, it is a subset of smartphones that approach that ideal goal of very dark black levels and very high peak brightness values: smartphones with AMOLED screens (the yellow markers with black levels approaching those of the OLED TVs). Smartphones, which are even more portable than laptops, will always have to contend with viewing conditions other than darkened rooms, and their peak brightness levels are consequently higher than those found on laptops and TVs.
Without AMOLED screens, though, the black levels of most smartphones are respectable, but nothing to write home about. Again, low black levels are not a priority on most mobile devices because, in a semi-bright or bright room, the human eye already has trouble resolving shadows and darker shades on a screen.
To make a long story short (too late), no matter what you do, you're going to have trouble watching a video at the beach. If you really want to be able to watch Hannibal anywhere, though, and you're willing to drop some extra cash, look for a laptop or a smartphone with an AMOLED screen. And while some screens will always stay shiny for touchscreen-related reasons, the screens of all of your devices are getting better every year, allowing you enhance your viewing pleasure while you watch Friends reruns.