Among all the other new features, macOS Mojave contains wallpapers that automatically change throughout the day based on the time of day.
So far, the operating system contains only one such wallpaper depicting a desert, in which day turns into night.
Change wallpaper by time of day
The new feature requires permission to use your location, just like night mode, to determine when the sun rises and sets.
For years, macOS has had a feature that changes the wallpaper automatically every time you turn on your computer, or after a certain period of time.
However, it simply switches between different wallpapers from the collection, rather than adjusting them to the time of day.
How to test changing wallpaper
Unfortunately, the effect of changing the wallpaper is difficult to describe in words. You need to see it yourself by choosing dynamic wallpaper in the desktop settings.
You can also get a sense of their work on the macOS Mojave preview site: drag the slider left and right to experience a new effect.
With the change of wallpaper, only wallpapers specially made for the function work.
How dynamic wallpapers are stored
MacOS Mojave has one changeable wallpaper called 'Mojave (Dynamic)'. Dynamic wallpapers are an addition to the new regular wallpapers. This is a desert by day, which is good for a light interface theme, and a desert at night, which looks great with a dark mode.
So what's the secret behind dynamic wallpapers in Mojave?
They use the economical HEIF (.HEIC) format, which was introduced last September along with iOS 11 and macOS High Sierra. You can find all the default wallpapers Apple by opening the Go menu in Finder and choosing Go to Folder.
Enter the line below and press Enter:
/ Library / Desktop Pictures
The standard Mojave dynamic wallpaper weighs 114 megabytes.
For comparison, all other wallpapers of the new version are stored in JPG format and weigh about 10 megabytes. Let's see if Apple gives you the ability to create dynamic wallpapers yourself.
About HEIC format
Apple must have taken multiple photos of the same place at time intervals to make a stunning dynamic wallpaper afterwards. Someone has already figured out that they consist of as many as 16 layers. You can even download every single JPG file on GitHub.
Also Read: How to Convert HEIF Images to JPEG Using Preview on Mac
If you open HEIC dynamic wallpapers in Previewer, you will only see one image, as the program does not support all HEIF features.
It is not yet clear whether users will be able to create dynamic wallpapers on their own in the future, or whether they will have to wait until Apple decides to add new ones.
What about iPhone
iOS contains dynamic wallpapers since the time of iOS 7, but they do not change depending on the time of day. They simply animate in response to movement.
In addition, iOS has live wallpapers from 2015, which are essentially short animations that come to life when you tap the lock screen with 3D Touch. On the home screen, they look like regular wallpapers.