PhotoDNA was developed by
Microsoft Research and
Hany Farid, professor at
Dartmouth College, beginning in 2009. From a database of known images and video files, it creates unique
hashes to represent each image, which can then be used to identify other instances of those images. The hashing method initially relied on converting images into a black-and-white format, dividing them into squares, and quantifying the shading of the squares, did not employ facial recognition technology, nor could it identify a person or object in the image. The method sought to be resistant to alterations in the image, including resizing and minor color alterations. similar methods are used for individual
video frames in video files. Microsoft donated the PhotoDNA technology to
Project VIC, managed and supported by the
International Centre for Missing & Exploited Children (ICMEC) and used as part of
digital forensics operations by storing "fingerprints" that can be used to uniquely identify an individual photo. The database includes hashes for millions of items. In December 2014, Microsoft made PhotoDNA available to qualified organizations in a
software as a service model for free through the
Azure Marketplace. In the 2010s and 2020s, PhotoDNA was put forward in connection with policy proposals relating to
content moderation and
internet censorship,) and various proposals by the
European Commission dubbed "
upload filters" by civil society such as so-called voluntary codes (in 2016 on hate speech after
2015 events, 2018 and 2022 on disinformation), copyright legislation (chiefly the
2019 copyright directive debated between 2014 and 2021),
terrorism-related regulations (
TERREG) and
internet wiretapping regulations (2021 "chat control"). In 2016, Hany Farid proposed to extend usage of the technology to
terrorism-related content. In December 2016, Facebook, Twitter, Google and Microsoft announced plans to use PhotoDNA to remove extremist content such as terrorist recruitment videos or violent terrorist imagery. In 2018 Facebook stated that PhotoDNA was used to automatically remove
al-Qaeda videos. By 2019,
big tech companies including Microsoft, Facebook and Google publicly announced that since 2017 they were running the
GIFCT as a shared database of content to be automatically censored. In 2022,
The New York Times covered the story of two dads whose Google accounts were closed after photos they took of their child for medical purposes were automatically uploaded to Google's servers. The article compares PhotoDNA, which requires a database of known hashes, with Google's AI-based technology, which can recognize previously unseen exploitative images. == Usage ==