LED Lights for ANPR Applications: Infrared Illumination
ProPhotonix has more than 15 years experience in developing LED lights for automatic number/license plate recognition (“ANPR”) systems. This post discusses ANPR systems and the growing range of applications for this technology as well as the requirements of LED lights for ANPR systems.
ANPR systems combine lighting and cameras to capture the number or license plate details on vehicles through optical character recognition (OCR). The system software identifies the characters which are then compared to a database. Any existing information attached to the registration number is then flagged.
ANPR Systems Applications
ANPR systems were initially developed in the late 1970’s for stolen vehicle detection but their use is now common in a wide array of law enforcement applications across the globe. In addition, other types of applications have developed as the technology has matured including the use of ANPR systems in parking, road tolling and journey time measurement applications.
Some of the earliest major installations of ANPR systems occurred with the introduction of the “Congestion Charge” zone in London and the installation of the “Ring of Steel” in the City of London. Countries around the world have rapidly adopted this technology and new applications continue to be identified.
Considerations for LED Lights for ANPR
Illumination is critical in ANPR applications as inadequate lighting will result in reduced accuracy and reliability of the overall system. Key considerations in developing the optimum illumination include wavelength, form factor, intensity and lifetime.
Generally, IR illumination is used in ANPR applications as it is invisible to the human eye, preventing distraction of drivers and also creates high quality images from the retro-reflective coatings on the plates. A recent development to expand the capability of ANPR systems, enabling high definition color recognition, is the incorporation of multiple carefully selected wavelengths.
In mobile and covert applications, the size or form factor of illumination is critical. A compact solution allows the light to be positioned closer to the camera which reduces the overall size of the system and also provides an improved angle of illumination.
Robustness and Reliability
ANPR lights must be robust and rugged. The systems are typically used outdoors and therefore can be exposed to extreme weather conditions. A robust system is required to ensure repeatable, reliable results.
ANPR systems typically operate at a significant working distance from the target requiring a high level of intensity to provide adequate illumination. In many applications, ANPR systems are used at heights where replacement of illumination would be difficult and hazardous. The long lifetime provided by LED lights are ideally suited to these applications.
ANPR Lights from ProPhotonix
ProPhotonix has a wealth of experience in developing LED lights for ANPR applications. Our products have been integrated in systems installed globally. Our 15 years of experience is testament to the reliability of our products and our ability to innovate as new trends develop. During these 15 years, we have continued to support our market leading customers as they have developed more advanced systems, improving system capabilities and developing new applications.