https://thenextweb.com/facebook/2019/08/02/facebook-open-sources-apis-to-help-fight-child-exploitation-and-terrorist-propaganda/

Facebook today announced it’s open-sourcing two technologies that help it curb the spread of problematic content like child exploitation, terrorist propaganda, or graphic violence online. These technologies aid the social network in detecting identical and nearly identical photos and video in order to weed out content that’s been flagged as being in violation of its policies.

The company said by using these open-sourced APIs, developers can create algorithms to match two similar files without the original image or video: