How does Apple's mobile phone camera blur the background?

There are two ways to blur the shooting background.

The first one is that if your Apple mobile phone supports dual cameras, it can be shot through Apple's own background blurring algorithm, and it is easy to take photos with blurred background, such as portrait photos, to let people know that the background is blurred. This is the result of the optimization of the mobile phone's own algorithm. Shooting doesn't need much skill, as long as you can open this way of shooting.

The other is the real shooting method that only blurs the background in photography. This applies to all Apple phones, whether you have a single camera or a dual camera.

The background is blurred by three elements: large aperture, long focal length and close range. Then the one taken with a known mobile phone is the most operable nearby, and the other two items are not up to the user. So what is the concept of proximity? That is, under the premise of normal focusing, the mobile phone should be as close as possible to the subject, and the background behind the subject should be as far as possible. This makes it easy to take photos with blurred background!