[eli5] How does face recognition work?
In: Technology
Mostly poorly.
The idea is to encode a set of facial features and then search a database of those those features. This technique was developed for fingerprints, and works really well for that.
However, fingerprints are essential “line” or “no line” in each pixel of the image. That’s a very low information density. Faces are much more complex, and the metrics like distance between the eyes and nose, have proven much less unique and powerful than fingerprint features.
It depends on the method. It can be as simple as comparing a photograph, but with some fudge factor for slight difference. Various AI can be used to account for different angles, hair, etc.
The iPhone takes a picture of your face and also scans your face contours in 3D, and then compares that to a stored image. Well, not really a stored image. Your initial registration is converted into a sequence of numbers representing your face, and subsequent scans are converted to numbers using the same algorithm and matched with what is on file.
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