ALPR / NPR Recognition Accuracy and Issues

By Carlton Purvis, Published Jan 15, 2014, 12:00am EST (Info+)

Sick of red light and speed cameras? A lot of people are. There are entire websites and web forums devoted to the public’s disdain for automated policing. But is there a way to beat them? Forget the aerosol sprays and chunky license plate covers [link no longer available]. In this post we show you, straight from a US government commissioned report, what things have been proven to give ALPR systems problems in reading plate numbers.

Because more and more law enforcement agencies are using automatic license plate recognition, the International Association of Chiefs of Police, with a grant from the National Institute of Justice was commissioned to asses ALPR implementation among U.S. agencies. It used results from 305 agencies across the U.S. including one of the biggest ALPR users, the Washington, D.C. Metropolitan Police Department [link no longer available]. The final report is where this data comes from.

The most common types of ALPR being used by U.S. agencies is mobile. Ninety-five percent of respondents said they used mobile APLR, while under 20% use fixed or portable.

*******, ****** *** *** ****** ******* and **** **** ** *** *****, according ** *** ******.

ALPR ******

******* **** ** **** **** ****** than ******** ***** ** ** *********** product. **** *** *** ***** **** things *********** ** *** ******:

***** ** **** ******

******* **** ******* ***** **** ** reflectivity, ****** **** *** ****, ***** or ******* “*** ***** *** **** software ** *********** * *********.”

******** ************

**** *****, *** ******* *** **** bars *** ****** ******** ************ **** can **** ** * ************* ******* plate. ******** **** ******** * ***** ** said *** ******* *** ********* **** have * ******* ****, *** **** suspect **** *** ****** **** **** just *** **** *******.

*** ****** ******** ***** ******** ** unreadable ******:


******* *****

“**** ******, ********** ******* *****, *** be ********* *** **********[*] ** ****,” *** ***** ****. It *****’* *** *** *** ** does *** ***** ****** *** * major ****** ** *** **** ** ALPR ****** ** ***** ** **** a *****. *** **** ** ***** designs **** **** ***** ** ***** and ****** * *****, *** ***** of *** ********** **** ****.

****** ******

***** ****** **** *** ****** *** accuracy ** * **** *** ******* the ******* *** ****** ** ***, the ****** ****, *** ** *****'* indicate ******* **** ** ****** ** worse *** *********** ***** *******. **** systems ****'* ********** ** **** ****** from ***** ******. *** ****** **** not ******** ***** ***** ***.

Capture *** **** *****

**** ** *.*. **** ******* *** read ***** ** **** ** ****, but ***** *** *** ****** ********** performance ***** *** ******'********* ****** ******:

*.*. *** ************** ******* *** ******** ********* *******, **** still ********* ***** ************. *** ********* from *** *****:

  • "********** ****** (**) ****** **********, *** example, *** ********* **** * ****** officer ******** **** **** ******* **,*** plates, ********* ** *** ******** ** 255 ******* *********, *** ************** ** 26 ******* **** ********* ********, ** vehicle ******** *********, * ****** *** 1 ******* ******* ***** ****, *** 3 ******* ** *** ****** ** 96 ***** ** *** **** ** days."
  • ** **** **** ** ******** ** the *.*. ****** ****** *** *********** scanned ***,*** ****** *** “**** *,*** were ******** ** * *******, ** rapes, ** *********, *** ********, *** burglaries, *** ******* ******, *** *******, and *** ********* *****.”

ALPR ****?

******-**** ******* ** *** ******** ***** ALPR **** ** ****** *** **** theft. **** (** *******) ******** ** increase ** ******* ********** *** ******* in **** ***** ***** ***** ******** ALPR. *** ***** **** ****** **** like **** ***********, ***** *** **** light *********** *** *********** ******* ****.


Are * *** ** ******** ***** ****?

*** ****** ** ******** ***** **** is ******* ******** ***** ****. ** the *** ******** ******** ** *** IACP, ** (**%) **** **** **** ALPR. * ******* ****** **** **** found **** ****** ******** **** ******** the ********** ** * ****** ****. Of ***** ****** ******** (**,*** ** more ********), ** ******* *** ****.

Do **** ******** **** ******** *** **** ***?

**** ** ***. **** ** ******* actually *** *** ******* ******** *** ALPR ***.

How **** ** **** **** ******?

****** ** ******* ** *** ******** surveyed ***** *** **** *** *** months, ** ******* ***** ** ************. Nearly **** (** *******) ******* ***** “hot *****” *****.

Comments (3)

As a manufacturer's rep, I know that we struggle with the issues above, but also personalized plates lack the reflective coating that standard-issued plates have, so that reduces the LPR camera's ability to "illuminate" the plate with IRs.

Does the report mention if white light is allowed in the US or only IR illuminator?

No it does not. The report mostly focused on stats and said very little about specific equipment.

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