License Plate Recognition (LPR) Systems: Function, Performance and Considerations for Law Enforcement Agencies [open pdf - 556KB]
"License plate recognition systems (LPRs) use optical character recognition (OCR) algorithms to allow computer software to read vehicle license plates. (These systems are also known as 'automatic license plate recognition systems,' or ALPR.) LPR systems usually consist of a few basic components: 1. A camera designed to take images of license plates (numbers and letters). 2. A computer software package that interprets the numbers/letters from the video captured by the LPR camera. 3. A database of previously stored 'hot lists' or previously read license plates. LPRs come in a variety of formats, including fixed, mobile and portable. This document includes a chapter that goes into more detail on each type, its strengths and weaknesses, and other important considerations. It also discusses performance and capabilities, including uses, speed and accuracy. Vendors often refer to speed and accuracy when promoting their systems, and understanding some of these capabilities will help an agency more fully comprehend the differences between various systems."
National Law Enforcement and Corrections Technology Center
National Law Enforcement and Corrections Technology Center: https://www.justnet.org/