ABOUT-FACE

Police forces are coming under fire for their trials of live facial recognition technology

- SARA RIGBY

What is it?

Live facial recognition (LFR), also known as automatic facial recognition, identifies people in a video in real time, using a set of photographs as a reference. When used in public, cameras scan a crowd and the software highlights any matches between members of the public and the people in their database.

How does it work?

The live video feed is scanned for faces. Each face that is found is then mapped by the software, taking measurements of facial features, such as the distance between the eyes and the length of the jawline, to create a unique set of biometric data. This dataset is then compared to a database of people to be identified. For the police, this database contains people with outstanding warrants. If the system judges the face to be sufficiently similar to someone in its database, this match is highlighted.

Who is using it?

In the UK, the London Metropolitan Police (the Met), the South Wales Police and Leicestershire Police have all trialled the technology in public since 2015. The system was tested at Download Festival in 2015, the Champions League final and Notting Hill Carnival in 2017, among other events, with the Met’s final test taking place on 14 February 2019. In these cases, the database consists of photos of people wanted by the police or courts. If the system makes a match, it presents the police with both images, so they can decide whether to stop and speak to the person. Unmatched faces are deleted straight away, and matched images are deleted after 30 days.