What Happens When You Look At Your iPhone? How 3D Face Unlock Actually Works

A viral video from a tech creator breaks down what happens inside the iPhone's notch every time you unlock it with your face, and why Apple hasn't been able to get rid of it.

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Read Time: 3 mins
Why does the iPhone have a notch? It houses the infrared sensors behind Apple's Face ID system.
Photo Source: Pexels

Why does the iPhone still have a cut-out at the top of the screen after all these years? According to a tech creator @techjunkies_official whose video has gone viral, the answer lies in one of the most heavily engineered parts of the phone: Face ID.

Using diagrams and close-up visuals, the creator explains that the top cut out holds far more than a front camera. He walks viewers through what happens from the moment a user looks at the screen to the moment the phone decides whether to unlock.

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The creator contrasts Apple's system with many Android phones, which he says simply take a picture and compare it with a stored 2D image. Face ID, he explains, has three components working at the same time.

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Step 1: Finding Your Face

First comes the flood illuminator. It sends out invisible infrared light, which helps the phone find the user's face, even in the dark.

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Step 2: Mapping It With Dots

Once the face is located, a dot projector beams around 30,000 tiny infrared dots onto it. These can't be seen with the naked eye, but the creator shows what the pattern looks like through an infrared camera.

Step 3: Building A 3D Map

The third piece is an infrared camera that reads the dot pattern. Using it, the phone builds a 3D map of the face, looking at details like the distance between the eyes and the distance between the nose and cheeks. This map is then matched against the face the user registered earlier. If they match, the phone unlocks.

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The creator also claims the cut-out looks smaller on the iPhone 18 Pro because Apple has moved the infrared camera behind the display.

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Where Your Face Data Goes

According to the creator, the mathematical data of a user's face is stored in the Secure Enclave, a separate, encrypted part of the phone. He says it has no internet access, and that even Apple cannot see what the stored data looks like.

Citing Apple's figures, the creator says the chance of someone else's face unlocking an iPhone is one in ten lakh. For Touch ID, Apple's fingerprint system, he puts it at one in fifty thousand.

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He uses these numbers to explain why Apple has stuck with this setup, even if it means keeping the sensors at the top of the screen.

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