Definition
Plain language
A way of fingerprinting images so visually similar ones get similar fingerprints.
As stated in the literature
A class of hashing functions producing locality-preserving image fingerprints, used in evidence-carrying agent verifiers to defend OCR channels against pixel-level manipulation.
Why it matters: It lets a verifier detect when an image has been substantively altered, even if the pixel bytes differ, which is crucial for evidence-based checks.
For example, two near-identical screenshots that differ only by JPEG compression produce nearly the same perceptual hash.
Heard on the show
“DOM provenance cross-referencing, Unicode confusable detection, accessibility-tree integrity checks, perceptual hashing for OCR.”Episode 062 — Treating Hallucinations as Exploits: A Gate-Based Architecture for Agent Safety