Craig Federighi comes clean on how Night Shift avoids ghosting artifacts when scrolling

By , Aug 8, 2016

iOS 9.3 Night Shift

Night Shift, a feature that was introduced in iOS 9.3, reduces the amount of blue light emitted from the display of your iOS device at night to help avoid disrupting your sleep cycle. In helping you getting a good night’s sleep, the feature looks at your geographical position and the time of the day to shift the colors to the warmer end of the spectrum.

But we all know that. Today, we learn that Apple’s engineers also built this feature in a way that avoids ugly artifacts that could appear on LCDs while scrolling and animating.

A customer from Germany emailed Craig Federighi, who is Apple’s Senior Vice President in charge of Software Engineering, to complain about Night Shift mode potentially emitting more blue light than F.l.ux, an iPhone app that serves the same purposes like Night Shift but was banned from the App Store following the release of iOS 9.3.

He received the following reply:

Given the display technology we push it as far as we can without introducing major red ghosting artifacts when scrolling / animating. (Unfortunately, the red phosphors in the LCD hold their color longer and when we shift the display too far into the red then scrolling results in irritating ghosting artifacts).

Here’s our video walkthrough of Night Shift Mode on iPhone and iPad:

To learn more, check out our Night Shift technology overview:

Night Shift Mode only works on 64-bit devices with iOS 9.3 or later.

It’s unsupported on the iPhone 5, iPhone 5c, iPhone 4s and earlier, fourth-generation iPad and earlier, fifth-generation iPod touch and earlier and the original iPad mini. Night Shift may be coming to the Mac, Apple Watch and CarPlay in the future.

Source: (Google Translate)

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  • John Wickham

    Anyone know if OLED displays have the same issue? Could reinforce rumors that the next iPhone will be OLED.

  • Y2J

    I just want a dark mode

    • Noohar


    • Steve Harvey

      Watch it be iPhone 7S exclusive. Every S model has a breakthrough software feature.

      • Y2J

        I wouldn’t even be surprised. But is a dark mode really breakthrough feature lmao? Probably to Apple smh

  • Bill

    I realize the article said Night Shift may be coming to the Mac but in the meantime, in case anyone is unaware, f.lux is available for Mac and it’s free.

  • AstrayPharaoh

    Why does everyone insist the F.lux was in the App Store? It never was. The developers distributed an opaque binary instead of the source code for sideloading. That’s what Apple did not like. F.lux was NEVER in the App Store.

    • JaeM1llz


  • Jordan

    Night shift looks at your geographical position? Why?

    • rahnolds

      Night shift uses your location to time the feature correctly, otherwise it might start warming your display in the middle of the day.

    • Diego Milano

      Correct, so it knows when it’s getting dark outside and it switches to a more warmer screen, that’s the only reason (and the only one it needs).

      • Jordan

        Thank you guys for your answers. I have asked that because I was only able to choose a period of time for night shift, I didn’t have the sunset to sunrise option. That was because “setting time zone” in location services was disabled.

      • Diego Milano

        That’s right! I had the same experience when I first installed iOS 9.3.3 after having used f.lux for centuries. I don’t know which one is better, and while f.lux developers may have way more experience and research in this field, I like to install the least amount of tweaks on my jailbroken device, which is one of the reasons why I did not install f.lux and I’m using Night Shift instead.

  • Diego Milano

    I didn’t know Night Shift was not supported by stock iOS on non-64-bit devices, CLEARLY a limitation imposed by Apple since I’ve been using iPhone for years and f.lux in all of its iterations. Maybe a jailbreak may fix this? Oh wait, it does, it’s called f.lux! Haha.

  • Denial

    I don’t get it. I’ve been using f.lux for the longest time on both iPhone 4s & 5s, on a much warmer setting than Night Shift’s maximum and I’ve never noticed any ghosting artifact while scrolling…

    • Bill

      Yeah I don’t know what they mean by that either. It’s probably just some bs they made up so it makes their feature seem better. Whatever though, if it works, cool. Honestly I don’t read too much into it, it’s just a ‘sales tactic’… you know?