If your iPhone or iPad features Apple’s white balance-compensating True Tone technology, you can quickly toggle it at any time right from iOS 11’s customizable Control Center.

What is True Tone technology?

Rather than use any special display hardware, True Tone subtly adjusts the white balance onscreen to match the color temperature of light around you whether you’re using the deviceunder overhead lighting or in direct sunlight. The goal is to fool your eye into perceiving the screen looks white like paper in any light.
By continually giving you just the right percentage, intensity and temperature of white light, True Tone makes images on the display look more natural, reduces eyestrain and makes reading text more comfortable on the eyes in all kinds of environments.
The following devices feature True Tone technology:
  • iPhone X
  • iPhone 8
  • iPhone 8 Plus
  • iPad Pro 12.9-inch (second generation)
  • iPad Pro (10.5-inch)
  • iPad Pro (9.7-inch)
True Tone uses an array of sensors in your device that continually measure both the intensity of the ambient light and its tone. iOS simply uses this information to shift the white point of the screen in different kinds of lighting.
A device without the True Tone feature tends to look bluish in warm, indoor light.

How to control True Tone from iOS 11 Control Center

To adjust display color temperature of your device on the fly, use Control Center to toggle True Tone:
1) Swipe up from the bottom edge of your iPhone to pull up Control Center. On iPads, swipe up from the bottom in any app (it doesn’t work on the Home screen) or simply double-click the Home button.
2) Now press the brightness bar with 3D Touch. On non-3D Touch hardware, tap and hold the bar.
3) Tap True Tone below the slider to toggle the feature quickly on or off.
TIP: You can also toggle Night Shift on or off from there.
Like before, you can enable or disable True Tone in Settings → Display & Brightness.
Keep in mind that vision accessibility features such as Invert Colors, Smart Invert, Grayscale and Increase Contrast might turn True Tone off.
Should you leave True Tone on all the time? That depends on your eyesight, lighting and environment. As a general rule of thumb, I prefer to enable True Tone for any kind of reading.

However, I keep it off when viewing my media, playing games and editing photos or video because those are the kinds of situations in which I don’t want display colors changed.