Memex
Perceptual Hashing
Intentionally maximizes the change of hash collision to detect similar images. Used by Google's Search by Image feature or Apple's CSAM. Perceptual Hashing
Algorithms and Their Performances
Zauner
- Fastest: block-mean-based perceptual image hash.
- Most discriminative: Marr-Hildreth operator-based hash function
Vulnerabilities
It's Not What It Looks Like: Manipulating Perceptual Hashing-based Applications
- TLDR: A delicately designed image can fool a perceptual hash application, making it classify two completely different images as the same.