At its 12 September event, Apple took the wraps off two new iPhone series: iPhone 8, 8 Plus and iPhone X. All three devices come with True Tone display, a technology which first made its appearance on iPad Pro. 

It works a lot like the white-balance-compensating system found in the iPhone's camera flash, allowing the iPad or iPhone screen to determine just the right percentage and intensity and temperature of white light you need. The idea behind the whole concept is that whites tend to look different under different light, but with True Tone enabled, the iPad can shift how the display looks no matter the lighting.

An adjusted white point should make reading text comfortable on the eyes, while the dynamically-adjusted brightness, when paired with the low-reflectance display, should equal more readability in direct sunlight. So, when the first iPhone 8 and iPhone X reviews surface, don't be surprised to hear the screen is easier to use whether indoors with overhead lighting or sitting by the window.

Here's everything we know about True Tone...

The iPad Pro, iPhone 8 and iPhone X feature sensors that measure the ambient light colour and brightness. The tablet or phone then uses this information to adjust its display. It can basically correct white point and illumination based on your environment lighting in order to render the right kinds of white under any light source. This technology isn't new, however, as some desktop monitors have been offering it for a long time.

The thing to remember is that the human optical system is constantly comparing near-white to perfectly white, and that a "better" white can affect our perceived contrast of whatever we're looking at, meaning an adjusted white point should be more comfortable on our eyes. It also means that the new iPhones and iPad Pro should be more readable in direct sunlight, thus improving its usability ever so subtly.

Here's how Apple explained its True Tone/Retina display when it was first launched:

"The 9.7-inch iPad Pro features advanced display technologies, including a True Tone display, which uses new four-channel sensors to dynamically adjust the white balance of the display to match the light around you for a more natural and accurate, paper-white viewing experience. The advanced Retina display is 25 percent brighter and 40 percent less reflective than iPad Air 2, making content even easier to see indoors and out. It uses the same wider color gamut as the iMac with Retina 5K display, delivering 25 percent greater color saturation for more vivid colours. A custom timing controller, photo alignment and oxide TFT deliver incredible color, contrast and clarity."

Yes. Unlike the iPhone's True Tone flash, the iPad Pro's True Tone display can be enabled and disabled, we suspect the same will be true of the iPhone X and iPhone 8. Under Settings, go to Display and Brightness, and switch on True Tone. Under this menu, you'll also see a Night Shift toggle. Night Shift works similarly to True Tone.

Night Shift is a feature introduced in iOS 9.3. It uses the iPad or iPhone's clock and geolocation to automatically adjust the colours in the display to the warmer end of the spectrum after dark. The result is a better night’s sleep for you. Night Shift basically works like True Tone, but for a different reason. It makes the screen get warmer closer to your bed time in order to reduce the amount of blue light emitted from the screen.

This will make the display appear more orangey. But a warmer display should be much more comfortable for late-night reading when ambient light is likely to be lower. Apple has suggested that blue light can affect our sleep by throwing off our circadian rhythm, which moderates our body clock. It suppress the secretion of melatonin, too. Harvard researchers and their colleagues have even proved this with experiments.

So, Night Shift should reduce the negative effects of using your device at night.