Perceptual Hashing

Effective automatic detection of Child Sexual Abuse Material (CSAM) is a continuing challenge, including the rapid detection of previously seen […]

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Academic publications
PDQ & TMK + PDQF – A Test Drive of Facebook’s Perceptual Hashing Algorithms

Dalins, Janis, Campbell Wilson, and Douglas Boudry. “PDQ & TMK+ PDQF–A Test Drive of Facebook’s Perceptual Hashing Algorithms.” arXiv preprint arXiv:1912.07745 (2019).


Efficient and reliable automated detection of modified image and multimedia files has long been a challenge for law enforcement, compounded by the harm caused by repeated exposure to psychologically harmful materials. In August 2019 Facebook open-sourced their PDQ and TMK + PDQF algorithms for image and video similarity measurement, respectively. In this report, we review the algorithms’ performance on detecting commonly encountered transformations on real-world case data, sourced from contemporary investigations. We also provide a reference implementation to demonstrate the potential application and integration of such algorithms within existing law enforcement systems.