Your Phone Doesn’t See Your Face — It Sees a Pile of Numbers

AI

How a 1968 edge-detection formula and a 2012 breakthrough taught machines to recognize faces without ever understanding what a face is

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This is Part 1 of the How AI Works series. I’ve always been curious about how AI actually works, so I spent a long time taking it apart — why your phone can still recognize you after a haircut, what exactly ChatGPT is computing in those three seconds before it replies, and how AI can pass the bar exam yet still lie to your face with complete confidence. This series is my exploration notebook. I discovered many fascinating things and wanted to share them with you. If you enjoy it, feel free to share and follow along.

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Every morning, you pick up your phone, glance at the screen, and it unlocks.

The whole process takes less than a second. You’ve never thought there was anything special about it.

But you might have noticed something odd: a few years ago, if you wore a mask, your phone often couldn’t recognize you. Yet if you changed your hairstyle, it could still unlock just fine. Why?

Don’t rush to answer. To understand this, we first need to figure out a more fundamental question: how exactly…