App justice: Graffiti artists are being targeted by a smartphone application that logs their tags and locations. Photo: Dean Sewell
Pattern recognition software for smartphones has been credited with helping to halve ''tag'' graffiti in a Sydney suburb could save ratepayers millions of dollars, police and developers claim.
The technology has been embraced by police, with Quakers Hill Inspector Brett Guyatt saying he sometimes shows suspects photos of 400 separate tags collated by the free-to-use technology.
Incidents logged on the VandalTrak application have skyrocketed since the not-for-profit organisation launched the app late last year.
Members of the public can take photos of graffiti when they see it and upload it to the VandalTrak online database where it is automatically logged by its location, catalogued by the traits of the tag and provided to police, council and other organisations such as Rotary Clubs and utility companies.
Authorities can then match similar tags and use the photos as evidence when attempting to charge people with vandalism.
Photos submitted by the public leapt from hundreds a month to 11,000 a month - or one every eight minutes during daylight hours - when the website released the app in October.
This month Gosford police used the database to accuse one teen of 35 tags and charge him with multiple accounts of malicious damage.
In Quakers Hill, the incidence of graffiti has fallen by 49 per cent after the arrest of 20 people and charges were laid with the help of the app. In one instance, an officer saw a 17-year-old boy tagging a bus shelter in the Hills district and matched the tag to eight others via VandalTrak.
VandalTrak creators estimate each police command could save 7.4 weeks of investigative time a year using the technology, the equivalent of $7 million across the state.
''Rapid removal and graffiti removal days have their place but you've got to go to the source of the problem and make offenders feel that nowhere is safe to get out their spray can,'' VandalTrak's director, Chris Winslow, said.
Police in Castle Hill, Ashfield, Gladesville, Fairfield, Lake Illawarra and the Blue Mountains have all adopted the technology.
The north shore command is about to start a pilot and has asked school principals to teach students how to use it.
''What we'll often do is go talk to an offender and their parents and show them the file we've been able to compile using VandalTrak,'' Inspector Guyatt said.
''When they realise we know a lot more than they think we know, they're often pretty shocked.''
He said graffiti was often a ''gateway'' offence but the new approach had diverted teens away from crime.
Councils, who have to pay for access to the database, have been reluctant to adopt the technology despite Attorney-General Greg Smith endorsing it.
Correction: The original version of this story said that the pattern recognition software was for iPhones.