The police are developing a national database of mugshots that can be matched with CCTV images to enable police to easily pick out potential offenders.
The system is being developed as part of a pilot scheme involving the forces in Lancashire, West Yorkshire and Merseyside.
The pilots have already generated a database of more than 750,000 facial images over the past 18 months.
Peter Neyroud, chief executive of the National Police Improvement Agency, told a parliamentary home affairs committee the database was being used to aid neighbourhood policing.
The parliamentary committee is considering whether the UK is becoming a surveillance society.