Multi-Level Genetic Algorithm for Acknowledging MultipleLicense Plates in a Single Image


Due to growing of engineering and use of vehicles the traffic monitoring system has now become an indispensable administrative portion in most of the developed and developing states. So, Automatic License Plate Recognition ( ALPR ) System plays an of import function in assorted existent clip applications like toll payment, electronic payment systems and parking fee payment, boundary line traversing control systems, designation of stolen vehicles etc. This is possible, merely because License Plate Numbers unambiguously identifies a vehicle. This ALPR follows two stairss localisation of licence home base and placing characters. This paper proposes the implement of the familial algorithm in multiple degrees for placing more than one licence home base in the individual image. Thus any figure of licence home bases in a individual image can be localized. By utilizing Multi-level familial process the localisation of the symbols on a two dimensional compound objects can be done with high truth rates compared to the bing 1. The extended experiments conducted depicted the higher truth with lesser calculation times.

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Keywords:Automatic License Plate Recognition, Character Recognition, Genetic Algorithms, Localization.


License home base ( LP ) is being used to unambiguously acknowledge a vehicle. License Plate Recognition ( LPR ) method plays a important function in assorted applications like parking fee payment, electronic payment system [ 2 ] , and traffic surveillance and to happen stolen autos [ 1 ] . For illustration in parking, licence home bases are used to mensurate the continuance of the parking clip. When a vehicle enters the toll, LP is automatically recorded and stored in database.

Figure 1: Block Diagram of Typical ALPR System

On go forthing, the LP is recorded once more and compared with the stored LP in the database. The clip difference is used for mensurating the parking fee. LPR is ready to hand and cost efficient as it is automated. Fig.1 shows the flow of traditional LPR system. Following subdivision gives the procedure of algorithm used in each measure in the LPR systems.

1.1 Pre-Processing:

Prior to the LPR phase, assorted pre-processing methods have to be applied to take shadows, to better the quality of the images, and to take noises in the image. Pre-Processing is an aid to acquire better the LPR rate. Basic methods include noise remotion, filtrating and cropping.

1.2 Localization:

This is the process of acquiring the licence home base subdivision out of an image. It uses basic image processing techniques jointly with determination doing depending on deterministic threshold. Without any anterior information on where the home base is located or how big the home base is, the complete image must be analyzed and inspected in order to take out campaigner parts. There are different processs on how to accomplish this, some algorithm imagine that the home base location of the image should non change by much [ 3 ] , and it must be adjusted by utilizing detectors [ 5 ] , therefore curtailing the hunt scope for fast consequences. Some techniques make usage of merely border inside informations for home base location [ 4 ] , and there are besides really complex processs such as fuzzed bunch and fuzzed logic [ 7 ] and vector quantisation [ 6 ] .

1.3 Cleavage:

Cleavage is the process that finds the alpha numeral characters on a licence home base. Assorted algorithms every bit good look for characters of equidistance and same colour and, with similar fount sizes to interrupt apart each single missive or figure. This chronological acknowledgment of the letters represents a characteristic set that is normally unvarying, despite of the type of LP. Character Segmentation divides each figure or missive where it is subsequently processed by Optical Character Recognition ( OCR ) methods [ 7 ] .

1.4 Character Recognition:

Once each single character or figure is extracted, it must be recognized in some manner. This procedure is called Recognition, to make so ; there are a figure of different solutions to this procedure. Two processs are particularly popular among many researches on licence home base acknowledgment. One of the methods is by agencies of Artificial Neural Networks ( ANN ) as classifier [ 3 ] . The ANN classifier must be trained earlier usage to acknowledge all the dissimilar characters, figures and symbols that need acknowledgment. The other manner is template fiting [ 5 ] [ 8 ] . In this method, a series of somewhat dissimilar templets of all types are stored in a database. Once an image is inputted for acknowledgment, stored templets are compared with the input image, and the best tantrum will reason its character/digit. This technique needs that the template database must be big plenty to cover all types of fluctuations.

2. Related Work:

The techniques discussed in this subdivision are regular techniques for home base acknowledgment. Apart from these methods, assorted other methods are besides discussed for home base acknowledgment. Most of these methods discussed in the literatures use more than individual method.

In [ 9 ] , for faster extraction of part of involvement ( ROI ) a method called skiding concentric window ( SCW ) is implemented. It is a two phase techniques incorporating two homocentric Windowss stretching from upper left corner of the image. Then numerical measurings in both Windowss are measured based on the cleavage grade which says that if the ratio of the mean or median in the two Windowss exceeds a threshold, which is set by the SCW, so the cardinal pel of the Windowss is considered to belong to an ROI.

To acknowledge multi-style LP a configurable technique is used in [ 10 ] . For acknowledging different manner of LPs, a user can configure the method by changing parametric quantity value in the LP acknowledgment algorithm.

In [ 11 ] a alone characteristic salient technique is used to pull out LP by utilizing outstanding characteristics like texture, form and colour. The writers utilized Hough transform ( HT ) to happen horizontal and perpendicular lines from rectangular vehicle LP and so processed it by changing ruddy, green, bluish ( RGB ) to hue-intensity-saturation ( HIS ) . Finally, the LP is segmented. This algorithm is tested on Pentium-IV 2.26-GHz Personal computer which is bundled with 1 GB RAM utilizing MATLAB.

To pull out figure home base characters in Indian scenario Ch.Jaya Lakshmi et Al. [ 12 ] proposed a novel method which depends on ripples and texture features. The writers besides utilised morphological operation for higher public presentation in complex backgrounds. Sobel mask is besides utilised to acknowledge perpendicular borders. The technique was implemented utilizing MATLAB. A Sobel border finder operator is besides used in [ 13 ] .

To acknowledge LP from CCTV footage, M.S.Sarfraz et Al. [ 14 ] implemented a fresh method for efficient localisation of LPs in video sequence and utilized an altered version of an bing method for acknowledgment and trailing. LP acknowledgment is a four phase procedure including happening affiliated constituents and contours, choice of rectangle country depending on aspect ratio and size, early acquisition for adaptative camera distance/height, localisation based on gradient processing, histogram, and nearest mean classifier. After covering out these stairss concluding acknowledgment consequence is fed as input for tracking.


The proposed theoretical account uses a sequence of techniques which are implemented in MATLAB. The ALPR Technique is loosely divided into following phases:

  • Image Acquisition.
  • Pre-processing ( Filtering ) .
  • Interest Oriented Region Extraction.
  • Cleavage of Fictional characters from the Extracted Region.
  • Character Recognition with Template Matching.
  • Exposing the Result.

The flow of LPR system in this work is depicted in the figure 2. The 2nd phase ( Preprocessing ) is done one time on complete image so it doesn’t demand to be repeated for multi-level loop. This besides reduces the clip taken to acknowledge. Once a home base is recognized the procedure signifier phase three is repeated until image stoping is reached.

C:UsersRIKYDownloadsALPR Flow.jpg

Figure 2: Flow of the Proposed Technique

3.1: Image Acquisition:

The basic measure in any ALPR is the capturing of an image by using electronic devices such as optical camera ; webcam etc. This paper utilizes the pre-captured images and will be saved as colour JPEG layout on the thrust. Input to the following phase is the image captured by a camera located at a distance of 1-2 metres off from the car as shown in following Fig 3.

Figure 3: Original Taken Image

3.2: Pre-Processing ( Filtering ) :

After the image acquisition, pre-processing methods are applied on image. When an image is captured from camera, there may be tonss of noises present in that image. These noises affect the acknowledgment truth greatly. So these noises must be removed from the images.

Grey Processing:

This measure engages in changing the colour image into a grey image. The algorithm is depends on different colour transform. Harmonizing to the R, G, B value in the image, it analyzes the value of grey value, and get the grey image at the same clip.

Median Filtering:

The noise will non be removed from images in grey processing. To take noise from the image, average filters are utilized so that image becomes free from noise. Removing of noise is a necessary measure in LPR system because it affects the acknowledgment rate of the system. Gray scale image is shown in following fig 4.

Figure 4: Converted Gray Scale Image

3.3 Interest Oriented Region Extraction:

Placing is a map that decides what characteristic of the vehicle ‘s image is the LP. Locating or placing a LP in this discrepancy can extra intensify the complexness for an algorithm to find what country of a vehicle contains a LP and what country is non. See, the technique must govern out a vehicle ‘s mirror, headlamp, grill, spine, bumper, etc. In common, algorithms expression for geometric forms of rectangular countries. However, since a vehicle can hold more than one rectangular object on it, algorithms are farther needed to formalize that the recognized object is surely a LP. To finish this, cardinal mechanisms of the algorithm expression for features that will make up one’s mind that the object is a LP. The algorithms expression for a similar background colour of combined proportion and contrast as a agency to distinguish objects on an image.

  1. Connected Component Analysis ( CCA ) :

CCA is a good utilised algorithm in image processing that gathers and scans an image pels in labelled constituents depending on pixel connectivity [ 15 ] . An eight-point CCA measure is used to happen all the objects inside the binary image produced from the earlier phase. The end product of this measure is an array of N objects. Fig. 5 shows an representation of the input and end product of this measure.

Figure 5: CCA ( a ) Input image ( B ) end product of CCA procedure

  1. Familial Algorithm Phase:

The preparation of the Genetic Algorithm stage to find the 2-D compound object acknowledgment job will be established in item, bespeaking the parametric quantities scenes and encoding method.

Chromosome Encoding

Encoding of a composite object such as the licence home base is completed based on the constituting objects in it. Given that the following measure after home base sensing is to acknowledge the Numberss, the chief procedure placing the home base figure should be incorporated as a lower limit. Other symbols in the licence home base can be added to broaden the word picture for more layout favoritism if desirable. An whole number encoding algorithm has been utilized where each cistronIis assigned an whole numberJthat depicts the index to one of theMeterobjects, end product from the size filtering phase. The information that will be used for each objectJis as follows:

  • The upper left corner co-ordinates (Ten,Yttrium) of the rectangle jumping the object ;
  • The tallness (Hydrogen) and width (Tungsten) of the rectangle jumping the object.

The end product of this stage will be an extracted licence home base with filtered version of the extracted part as shown in the figure 6.

Figure 6: Extracted Region and Filtered version of that extracted Region

3.4: Cleavage:

This phase gets the end product of the old phase as input and splits the each and every character in the LP image by using cleavage algorithm and the length of the figure home base is besides detected, and correlativity is generated with that of the database if both the value is equal so it will bring forth the value A – Omega and 0-9 and, in conclusion converts the metameric characters to twine and showed them in edit box, Figure 7 shows the metameric characters.

Figure 7: Segmented Fictional characters

3.5: Fictional character Recognition:

The Optical Character Recognition is utilized used to compare the single character against the stored complete alphameric database. The OCR basically uses templet fiting method to compare individual character and eventually the figure is detected and stored in a templet format in a variable. The templet is so compared for happening the similarity step with the alphameric database for the acknowledgment. The figure 8 shows the stored database.

Figure 8: Stored Database

Finally the similarity step is calculated and based on that similarity step the OCR assigns the appropriate category to single section. The consequence subdivision so converts the assigned categories to ASCII and displays the concluding recognized twine.

The complete procedure is repeated until all the home bases in a individual image are recognized. The multi-level algorithm uses an loop based process to acknowledge multiple licence home bases in a individual image.

4. Analysis:

The following of import thing is to analyse the public presentation of the proposed technique where the most of import prosodies are considered and extended testing is done to demo the public presentation of the proposed technique. The prosodies considered here are the

  • Recognition Accuracy & A ;
  • Time taken to Recognize.

The proposed technique is tested with multiple licence home bases in individual image and compared with the bing techniques and the consequences are tabulated at the terminal of this subdivision.

I:Multi License PlateFull.jpgThe below figure 9 depicts the inputted image with multiple licence home bases in a individual image and the recognized end product of those license home bases.

Figure 9: Multiple licence home base acknowledgment procedure

The above figure shows the input image with 4 licence home bases and their corresponding recognized end products. The proposed technique is tested with 100 different licence home bases and as noted the technique performed good and recognized about all of them precisely. The overall truth achieved is 98 % . The consequences are depicted in table 1 and figure 10.

Table 1: Accuracy consequences

Technique Used

Entire no. of Home plates

Recognized Precisely

Recognized falsely





SCW [ 9 ]




Ripples [ 12 ]




Figure 10: Accuracy Comparison of Different Techniques

Coming to the clip taken to acknowledge the home bases the proposed technique is tested with different possible conditions and the mean clip taken to acknowledge the home bases is noted as 4 Seconds. As compared to the techniques in [ 9 ] & A ; [ 12 ] harmonizing to their consequences the mean clip taken is about 7-8 Seconds.

5. Decision:

This paper proposed an ALPR technique which uses multi-level Genetic Algorithm to acknowledge multiple licence home bases in a individual image. The paper discussed the general procedure of the ALPR systems and with some traditional algorithms. The proposed technique recognizes multiple licence home bases in a individual image. Connected Component Analysis is used to pull out the involvement oriented part and so that part is fed as input to the GA for figure home base extraction. The technique is tested with 100 different home bases for legion times and the analysis depicts promising consequences compared to the bing techniques. Further survey is required to further accomplish the acknowledgment truth.

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