Flickering image content: Light effects can be muted on Apple devices

With the new “Dim flickering light” option, Apple offers the option in the updated operating systems tvOS 16.4, macOS 13.3, iPadOS 16.4 and iOS 16.4 to dampen rapid changes between light and dark image content or stroboscopic effects. This should help light-sensitive people and those with photosensitive epilepsy to watch films, series and videos without the risk of damage to their health. What is interesting about the new technology is that Apple does not keep the underlying algorithm for itself, but makes it publicly available. For more information and instructions on how to enable accessibility, see this guide.

Setting against rapid light changes and stroboscopic effects

The new setting on the most common Apple devices with video output is an accessibility feature. Accordingly, you will also find them in the so-named area of ​​settings / system settings. The description for the slider that you activate for the option reads this: "Video content with repeated flickering or strobing lights is automatically dimmed.“ Depending on the device or operating system, the way to the setting is a bit different. Also, be careful when trying it out with related video content after activating it - I haven't found any test reports confirming that the new feature works properly.

iPhone and iPad guide: Dim flickering light on iOS / iPadOS

Here is the step-by-step guide for iPhone and iPad iOS 16.4 and iPadOS 16.4:

1. Opens the Settings on the Apple iPhone / iPad
2. Tap the menu item Accessibility an
3. Select the point from its list Exercise from
4. Tap the Dimmer Flickering Light slider
5. The option is enabled when the slider is highlighted in green

Mac guide: Dim flickering light on macOS

Here are the step-by-step instructions for the Mac from macOS 13.3:

1. Click on the in the top left Apple logo the menu bar ()
2. Select the item from its menu System settings ... from
3. In the list on the left, click the Accessibility an
4. Also opens the submenu here Show
5. Click on the Dimmer Flickering Light slider so it is highlighted in blue

Apple TV guide: Dimming flickering lights on tvOS

Here are the step-by-step instructions for Apple TV from tvOS 16.4:

1. Opens the Settings on the Apple TV
2. Navigates to the menu item Responsiveness
3. Then select the point Exercise from
4. Activate the "Dim flickering light" slider here as well
5. Now you can return to the media selection

Background and algorithm: "Video Flashing Reduction" explained

Apple has provided a document on its developer platform that shows the background of the new technology. The new release entitled “Video flash reduction. Background and Algorithm“ in v1.0 from March 2023 you can with this link view as PDF. After an introduction to the topic and the technical hurdles in the development, there is a detailed description of the algorithm used to counter heavily flickering video content. After this nine-page insight, there is a look ahead, as well as appendices and a bibliography. All in all, a scientific paper that can provide all those interested with the necessary starting points for dealing with the topic.

Opportunities for developers to implement in their own apps

Apple also urges app developers to take the changes in settings outlined above into account for their interface as well. Under the headline "Responding to changes in the flashing lights setting" is it [called at this point: "Adjust your UI when a person chooses to dim flashing lights on their Apple device.– To get familiar with the matter, a sample code can be downloaded and used for your own project. The tags on the page show that developers working on apps for iOS 16.4 and newer, iPadOS 16.4 and newer, and Xcode 14.3 and newer are primarily addressed here.

Swift, MATLAB and Mathematica projects also available on Github

In addition to the sample code on Apple's developer website itself, the technology for detecting, warning and / or dimming flickering video content is also made available on Github. In addition to the "Video Flashing Reduction" technique for Swift, you will find implementations of the algorithm for MATLAB and Mathematica there. You come to the overview of the project with this link. Both the Github content and the example code on the developer website indicate that there is a flickering light video in the material provided. So if you are photosensitive and want to watch the thing, you should approach the sample video with caution.

Johannes Domke

After graduating from high school, Johannes completed an apprenticeship as a business assistant specializing in foreign languages. But then he decided to research and write, which resulted in his independence. For several years he has been working for Sir Apfelot, among others. His articles include product introductions, news, manuals, video games, consoles, and more. He follows Apple keynotes live via stream.