TagMaster NA: License Plate Recognition 101

TagMaster share the ins and outs of license plate recognition.

License Plate Recognition (LPR) is one of the fastest growing and most innovative technology solutions on the security and vehicle access control market today. You have probably heard of LPR, but you might ask, what exactly is LPR and how does it work?

LPR technology is the use of a specialized camera that identifies the alphanumeric characters on a vehicle license plate and uses optical character recognition and other methods to convert the text into an electronic and usable format for data. LPR has been established as a standard for vehicle identification in Europe and in the last decade has continued to exponentially gain traction and popularity throughout North America.

All LPR cameras rely on an ‘engine’ which allows the image taken from the camera to be output as the text of the license plate characters. There are various other algorithms at play to assist the LPR engine in determining the highest confidence result of a license plate.

TagMaster NA’s LPR cameras offer an all-in-one solution with dual cameras within the same weatherproof housing and onboard processing. This means the “OCR Engine” and associated algorithms needed for processing a plate picture into data happen without a server needed. The CT45 LPR ensures the highest possible accuracy for non-reflective, partially reflective, damaged, and dirty license plates in any lighting condition. The cameras work together to output the highest confidence read based on the internal logic at play.

Behind the scenes

The algorithms working behind the scenes of our cameras are Plate Localization, De-Skewing, Syntax, Segmentation, The OCR Library and Neural nets.

Plate localization is the camera's ability to identify the position of the license plate within the image and focus on the plate and disregard background noise/other text or images.

De-Skewing is the ability of the LPR camera to make mathematical angular corrections to assist in decoding plates that are taken at various angles and speeds and correct for perspective and rotation.

Syntax assists the camera to determine the license plate state or origin and increases accuracy by understanding the predictable pattern of alphanumeric characters based on the state. Checking the characters and sequence against a specific set of rules results in much higher confidence in plate recognition.

Segmentation involves identifying the individual characters on the vehicle plate using a few different methods. Finding the white spaces between the letters called Whitespace delineation helps to separate the characters and better identify them.

Optical Character Recognition (OCR) is the brains behind the operation and includes pattern matching, edge tracing, proportion, and pixel repetition for recognizing the characters and the ultimate result of the license plate read. The OCR engine ensures that overall confidence is as high as possible by matching the individual characters and patterns to produce the best possible result.

Neural Nets are the ability of the OCR engine to adapt and recognize distinct types of fonts, colors and sizes. Our team of OCR Engineers works to ensure current and new issues, and changes to plate issuances are updated and maintained in the OCR library to ensure the highest accuracy in all regions for all plates possible. This helps the system ‘learn’ from every plate it reads, and the more ‘experience’ the camera has the better the reads and more accurate it is.

While it may seem instantaneous (all of this image processing is done within milliseconds), there is a lot that goes into getting an accurate plate read. LPR reduces cost and optimizes vehicle throughput/security/accuracy/revenue while ensuring the user experience is as frictionless and convenient as possible.

TagMaster NA’s CT-45 LPR camera is the culmination of the market demand for future-proof and ready solutions able to adapt and improve vehicle access control operations. With our solution, you get a BIG performance with the smallest hardware footprint possible.

TagMaster NA’s CT-45 LPR camera

About TagMaster NA TagMaster NA

TagMaster North America is a leading provider of long-range automatic vehicle identification (AVI) solutions, offering dual platforms of radio frequency identification (RFID) and license plate recognition (LPR) technology, addressing a wide range of challenges in AVI, ground transportation, and access control. Our diverse family of readers, tags, cameras, accessories, and software solutions offers maximum adaptability and versatility.


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