A photo of a dog, the word “dog”, and the sound of barking arrive through three different doors — and land in the same neighbourhood.
Send one thing in, four ways
Each door has its own encoder — for an image, that means scanning the pixels and gradually boiling them down to "what's in the picture," the same way page 2 boiled a sentence down to chunks. What comes out the other side is the same kind of thing either way: a point in the shared space.
The problem it solves
How it works
The modern version
The shared-space picture above is the intuition. Today’s big models mostly do this instead — which is why a picture and a question about it fit on the same desk.
So what
Searching your photos by typing a sentence is not clever image recognition. It is one nearest-point lookup, in a space that stopped caring what format things arrived in.