Introduction to ANPR

Automatic Number Plate Recognition (ANPR), also known as Automatic License-Plate Recognition (ALPR), Automatic Vehicle Identification (AVI), or Car Plate Recognition (CPR), is a surveillance method that uses Optical Character Recognition (OCR) and other methods such as segmentations and detection to read vehicle registration plates.

The best results in an ANPR system can be obtained with an infrared (IR) camera, because the segmentation steps for detection and OCR segmentation are easy, clean, and minimize errors. This is due to the laws of light, the basic one being that the angle of incidence equals the angle of reflection; we can see this basic reflection when we see a smooth surface such as a plane mirror. Reflection off of rough surfaces such as paper leads to a type of reflection known as diffuse or scatter reflection. The majority of number plates have a special characteristic named retro-reflection—the surface of the plate is made with a material that is covered...