License Plate Location And Recognition

The technology of the automatic vehicle identification is one of the important studies in the intelligence traffic system.License Plate Recognition is the organic part of the Intelligent Transportation System(ITS),which play a key role in the ITS.One function of the ITS is achieve the aim of automatic control and manage.Then the License Plate Recognition can provide the needed vehicle identification information for the subsystems of the ITS.With those it can accelerate the automatic manage of the traffic system.LPR can be used during the crossways,carbarn manage,big park,highway,the charge system of the bridge and so on.It is the key technology to solve the traffic bottleneck problems that are made by the traditional manage mode during the modern society.With more fast development of transportation and the use of higher-tech in the automatic monitor and control,the AVI seems more important.In this thesis,we did a lot of research on LPR key technology based on image aimed at the requirements.The LPR system is composed with vehicle Plate capture,license Plate recognition module,database managing and data transfer through net etc..This Paper studies on the algorithms of license Plate recognition module.The module is composed with image Per-Process,Plate location,char segmentation and char recognition.Works have been done in this paper:1.Research on LPR principle;2.Research on the Plate Location and segmentation method through Edge Detection and region search;3.Research on the Plate Location pre-process method;4.Research on character isolates method.Following are the main Work.1.The PLR system principle and universal PLR are analyzed,the following works are accomplished:Ⅰplate location and type sense.A) Magnetic induction detection;B) Transportation microwave sensor;C) Infrared detection;D) Ultrasonic detection;ⅡAnalysis on PLRA) IC Card recognition technology;B) Bar code recognition technology;C) Recognition technology based on image comprehension;D) Recognition technology based on NN;E) Digital image vehicle recognition.2.The difficulty of plate location and segmentation which is the key technology of PLR is studied.Assorted and concluded the classic method of the plate location and segmentation.Based on these the Plate Location method through Edge Detection and region search are designed and realized.During the process of the method,the paper discuss the Edge Detection,region search and plate region re-distinguish that are three key taches.ⅠAnalysis on plate location.A) Method based on linear detection;B) Method based on threshold;C) Method based on gray edge detection;D) Method based on colorful image.ⅡThe paper finished the Plate Location method through Edge Detection and region search based on upwards researches.A) Basic way of the method;B) Method realization.3. The predispose method of Plate Location module is studied.Then Subsection gray transform function is designed.Using hough transformation and image reverse rotation to rectificate slant,the following works are accomplished:ⅠPredisposal on image.A) Plate image enhancement;B) Gray transform.ⅡEquilibrium disposal.ⅢSlant rectification and zoom disposal.ⅣPlate image binarization.4.We analyzed the classic way and method of the problem of the character isolate,designed the character horizontal and vertical segmentation method,and designed the segmentation result method to boost the veracity.ⅠHorizontal segmentation method based on edge detection;ⅡVertical segmentation based on projection and knowledge;A) Calculate vertical projection;B)Apices-vale inspection method principal vertical segmentation;C) Character split and unites;D) Wipe off the forward and back disturbs.Main achievement are accomplished in this paper:1.We present a new method, which is mufti-vehicle plates segmentation and recognition.First,we use the statistics and the feature extraction to extract the background,which contain the vehicle license plates.Second,after making sure of the location of vehicle license plates,characters in the vehicle license are divided and the location of the characters is located.At last, we use the BAM to recognize the vehicle license precisely.2.Designing and realizing method through Edge Detection and region search.During the realizing process of the method,the paper discuss the Edge Detection,region search and plate region re-distinguish that are three key taches.3.Subsection gray transform function is designed.4.Horizontal and vertical segmentation method is designed.5.Syncopate result rectification tache are designed to improve the veracity of character syncopate.Further Research Works can be continued further as followed:1.For people having researched the LPR for many years and the time limitation, we take the image manipulation as the method without theory innovation.2.The LPR did not use the colorful information and detect on the gray image, next we can bring colorful information to improve the effect of plate location and character binarization.3.Improving the toughness of character and recognition probability to deformity,empoison and distortion,next our work is to seek character which is more steady and choose more effective class sensor.4.The recognition probability of Chinese characters is lower than letter and there are more superior room.