[fallingknife]

I have a hard time believing that this algorithm will be able to resist simple image manipulations while still being sensitive enough to avoid false positives.

[diebeforei485]

I have similar qualms with this, because this is increasing the number of photos scanned by 2-3 orders of magnitude, and the number of false positives presumably also increases correspondingly.

[midev]

What algorithm are they using?

[fallingknife]

I don't know. If they made that public it would be completely ineffective.