用于视频交通检测监控系统的车牌自动识别算

356200612Vol.35No.6JOURNALOFHEBEIUNIVERSITYOFTECHNOLOGYDecember20061007-2373(2006)06-0082-06300072HoughBPU412.6AStudyofVideoVehicleEtectionandMonitoringSywtemBasedAutomaticVehicleLicensePlateRecognitionAlgorithmCHENYangYANGZhao-xuan(SchoolofElectronicInformationEngineering,TianjinUniversity,Tianjin300072,China)AbstractThispaperstudiesthealgorithmofAutomaticLicensePlateRecognition(ALPR)appliedinVideoVehicleDetectionandMonitoringSystem.Tomeetthesystem'srequirementofaccuracyandspeed,animprovedalgorithmoforientalcorrectionbasedonHoughTransformandawayofcharactersegmentbasedonMarkovRandomField(MRF)andGeneticAlgorithm(GA)arepresented.TheresultsofexperimentsdemonstratethattheaccuracyandspeedofALPRareeffectivelyimprovedwhenthisalgorithmisapplied.KeywordsLicensePlateRecognitionorientationcorrectionbinarizationBPalgorithms0311[1]12006-05-160331833111982-836232×288JPEG22Sobel[2]Hough2.1Hough[3],,3=cos+sin(1)(1),0,0,=0cos+0sin,,,,1Fig.1StructureofvideovehicledetectingandmonitoringsystemDDXX,25,PSTN)1212Fig.2Flowchartofalgorithmforsegmentationoflicenseplateregion3Fig.3Geometricalexplanationoftheequationinline-polarcoordinatessystemminminmaxmax84350,00Hough,(1)12.2Hough[-2020]0.12×20/0.1+1=401[-11],[-2020]20×2/1+1=41[-0.10.1][-11]2×1/0.1+1=216280%Hough2.2.1maxmax2.2.20,,(2),tg0==tg0(2)3[2]44Fig.4Flowchartofalgorithmforcharacterssegmentation7856[3](MRF)(GA)3.1MRFMRF[4]=,=,1)02)|)=|)=,MRF=,=,Hammersly-CliffordMRFGibbs=1exp(3)(3)=Gibbs=|;)|=;=122exp222(4)=,(4)||=1exp|(5)|=222+log3.2(MAP)=argmaxlog+log|(6)(3)(5)MAP=argmin+|(7)8635(7)ICM|=,MRFMRF1=argmin+|234=121205(EM)635=1001=0.92=0.01=0.0014[3]3BP7BP65Fig.5Contrastoftheresultsbyusingdifferentbinarizationalgorithms6BPFig.6FlowchartofBPalgorithmENDnonoyesyes876[5]5Hough90%94%5VC++6.0Pentium42.0GCPU512M0.45s0.6s[6][1]YangZhaoxuanLinTaoLiXiangpingetalDigitalSignalProcessingBasedRealTimeVehicularDetectionSystemTianjin,TransactionsofTianjinUniversity200511(2)119-124[2]VisualC++[M]2004214-255[3]RafaelCGonzalezRichardEetalDigitalImageProcessing[M]BeijingPublishingHouseofElectronicsIndustry2003567-642,693-750[4]YuntaoCuiQianHuangAutomaticLicenseExtractionfromMovingVehicles[J]ImageProcessing19973126-129[5]AbhijitSPandyaRobertBetaiPatternRecognitionwithNeutralNetworksinC++[M]BeijingPublishingHouseofElectronicsIndustry199957-93[6][A](HHME2005)[D]2005102006122260