The Guide “10 Tips For Best Free Flow ANPR Deployment” aims to provide a useful list of characteristics and features of ANPR cameras to be used in free-flow, auto-triggered and high-speed traffic control applications.


Detection and Recognition Rates

Overall performance of an ANPR camera is computed by multiplying the Detection Rate by the Recognition Rate. Detection rate has been analyzed in Tip #4, and it is measured by the number of vehicles (plates) detected by the ANPR camera over the Total number of vehicles going through the camera’s field of view. Detection Rates range is 50% to 99%, depending on the selected ANPR solution.

Better Recognition with Good Quality images

Recognition rate mainly depends on two factors:

  1. The quality of the license plate image
  2. OCR (Optical Character Recognition) engine.

OCR is a “mature” technology, and top recognition accuracy can be reached if the input image has good quality. Thus, quality of the license plate - in terms of Resolution (Tip #1, Tip #2) and Illumination (Tip #3)- is a prerequisite for best performance of the OCR engine.

So, real improvement in ANPR comes from a good quality image of the license plate.


Imagsa's Atalaya ANPR camera ensures a good quality of the license plate image by using a 2 Megapixel image sensor, and an auto-adaptive Multi Exposure technique at high speed (250 FPS). Therefore, top License Plate Recognition rates can be achieved.

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