DESIGN AND IMPLEMENTATION OF AN AUTOMATED CAR PLATE NUMBER RECOGNITION SYSTEM
Abstract
INTRODUCTION
1.1 Background of the study
Massive integration of information technology into all aspects of modern life caused
demand for processing vehicles as conceptual resources in information systems.
Because a standalone information system without any data has no sense, there was also a need to transform information about vehicles between the reality and
information systems. This can be achieved by a human agent, or by special
intelligent equipment which is able to recognize vehicles by their number plates in
a real environment and reflect it into conceptual resources. Because of this, various
recognition techniques have been developed and car plate recognition systems are
today used in various traffic and security applications, such as parking, access and
border control, or tracking of stolen cars.
A car registration plate is a metal of plastic plate attached to a motor vehicle for
official identification purposes. The registration identifier is a numeric or
alphanumeric code that uniquely identifies the vehicle within the issuing region’s
database. In some countries, the identifier is unique within the entire country, while
in others it is unique within a state or province. Whether the identifier is associated
with a vehicle or a person also varies by issuing agency. Depending on the country,
the vehicle registration plate may be called a license plate, tag, car plate or number
plate. Most governments require a registration plate to be attached to both the front
and rear of a vehicle, although certain jurisdictions or vehicle types, such as motorboats require only one plate, which is usually attached to the rear of the
vehicle. National databases relate this number to other information describing the
vehicle; such as the make, model, color, year of manufacture, engine size, type of
fuel used, Vehicle Identification (Chassis) Number and the name and address of the
vehicle’s registered owner or keeper.
The term access control refers to the practice of restricting entrance to a property, a
building, or a room to authorized persons. Physical access control can be achieved
by a human (a guard, bouncer, or receptionist) through mechanical means such as
locks and keys, or through technological means such as access control systems.
Automatic car plate recognition (ACPR) is a mass surveillance method that uses
optical character recognition on images to read vehicle registration plates. They can
use existing closed-circuit television or road-rule enforcement cameras or ones
specifically designed for the task. They are used by various police forces and as a
method of electronic toll collection on pay-per-use roads and cataloging the
movements of traffic or individuals.
ACPR can be used to store the images captured by the cameras as well as the text
from the license plate, with some configurable to store a photograph of the driver. Systems commonly use infrared lighting to allow the camera to take the picture at
any time of the day. ACPR technology tends to be region-specific, owing to plate
variation from place to place.
The software aspect of the system runs on standard home computer hardware and
can be linked to other applications or databases. It first uses a series of image
manipulation techniques to detect, normalize and enhance the image of the car plate,
and then optical character recognition (OCR) to extract the alphanumeric of the
license plate. ACPR systems are generally deployed in one of two basic approaches: one allows for the entire process to be performed at the lane location in real-time,
and the other transmits all the images from many lanes to a remote computer location
and performs the OCR process there at some later point in time. When done at the
lane site, the information captured of the plate alphanumeric, date-time, lane
identification, and any other information required is completed in approximately 250
milliseconds. This information can easily be transmitted to a remote computer for further processing if necessary, or stored at the lane for later retrieval. In the other
arrangement, there are typically large numbers of PCs used in a server farm to handle
high workloads. Often in such systems, there is a requirement to forward images to
the remote server, and this can require larger bandwidth transmission media.
During the 1990s, significant advances in technology took automatic car plate
recognition systems from limited expensive, hard to set up, fixed based applications
to simple “point and shoot” mobile ones. This was made possible by the creation of
software that ran on cheaper PC based, non-specialist hardware that didn’t require
the pre-defined angles, direction, size and speed in which the plates would be passing
the cameras field of view.
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