车牌识别外文翻译文献综述.docx

车牌识别外文翻译文献综述.docx

《车牌识别外文翻译文献综述.docx》由会员分享，可在线阅读，更多相关《车牌识别外文翻译文献综述.docx（20页珍藏版）》请在冰豆网上搜索。

车牌识别外文翻译文献综述

LicensePlateRecognitionBasedOnPriorKnowledge

Abstract-Inthispaper,anewalgorithmbasedonimprovedBP（backpropagation）neuralnetworkforChinesevehiclelicenseplaterecognition（LPR）isdescribed.Theproposedapproachprovidesasolutionforthevehiclelicenseplates（VLP）whichweredegradedseverely.Whatitremarkablydiffersfromthetraditionalmethodsistheapplicationofpriorknowledgeoflicenseplatetotheprocedureoflocation,segmentationandrecognition.Colorcollocationisusedtolocatethelicenseplateintheimage.Dimensionsofeachcharacterareconstant,whichisusedtosegmentthecharacterofVLPs.TheLayoutoftheChineseVLPisanimportantfeature,whichisusedtoconstructaclassifierforrecognizing.Theexperimentalresultsshowthattheimprovedalgorithmiseffectiveundertheconditionthatthelicenseplatesweredegradedseverely.

IndexTerms-Licenseplaterecognition,priorknowledge,vehiclelicenseplates,neuralnetwork.

I.INTRODUCTION

VehicleLicense-Plate（VLP）recognitionisaveryinterestingbutdifficultproblem.Itisimportantinanumberofapplicationssuchasweight-and-speed-limit,redtrafficinfringement,

roadsurveysandparksecurity[1].VLPrecognitionsystemconsistsoftheplatelocation,thecharacterssegmentation,andthecharactersrecognition.Thesetasksbecomemoresophisticatedwhendealingwithplateimagestakeninvariousinclinedanglesorundervariouslighting,weatherconditionandcleanlinessoftheplate.Becausethisproblemisusuallyusedinreal-timesystems,itrequiresnotonlyaccuracybutalsofastprocessing.MostexistingVLPrecognitionmethods[2],[3],[4],[5]reducethecomplexityandincreasetherecognitionratebyusingsomespecificfeaturesoflocalVLPsandestablishingsomeconstrainsontheposition,distancefromthecameratovehicles,andtheinclinedangles.Inaddition,neuralnetworkwasusedtoincreasetherecognitionrate[6],[7]butthetraditionalrecognitionmethodsseldomconsiderthepriorknowledgeofthelocalVLPs.Inthispaper,weproposedanewimprovedlearningmethodofBPalgorithmbasedonspecificfeaturesofChineseVLPs.TheproposedalgorithmovercomesthelowspeedconvergenceofBPneuralnetwork[8]andremarkableincreasestherecognitionrateespeciallyundertheconditionthatthelicenseplateimagesweredegradeseverely.

II.SPECIFICFEATURESOFCHINESEVLPS

A.Dimensions

Accordingtotheguidelineforvehicleinspection[9],alllicenseplatesmustberectangularandhavethedimensionsandhaveall7characterswritteninasingleline.Underpracticalenvironments,thedistancefromthecameratovehiclesandtheinclinedanglesareconstant,soallcharactersofthelicenseplatehaveafixedwidth,andthedistancebetweenthemediumaxesoftwoadjoiningcharactersisfixedandtheratiobetweenwidthandheightisnearlyconstant.Thosefeaturescanbeusedtolocatetheplateandsegmenttheindividualcharacter.

B.Colorcollocationoftheplate

TherearefourkindsofcolorcollocationfortheChinesevehiclelicenseplate.ThesecolorcollocationsareshownintableI.

TABLEI

Categoryoflicenseplate

Colorcollocation

smallhorsepowerplate

bluebackgroundandwhitecharacters

motor truckplate

yellowbackgroundandblackcharacters

military vehicle andpolicewagonplate

blackbackgroundand thewhitecharacters

embassyvehicleplate

whitebackgroundandblackcharacters

Moreover,militaryvehicleandpolicewagonplates containaredcharacterwhichbelongstoaspecificcharacter set.Thisfeaturecanbeusedtoimprovetherecognitionrate.

C.LayoutoftheChineseVLPS

Thecriterionofthevehiclelicenseplatedefinesthe characterslayoutofChineselicense

plate.AllstandardlicenseplatescontainChinesecharacters,numbersandletterswhichareshowninFig.1.ThefirstoneisaChinesecharacterwhichisanabbreviationofChineseprovinces.ThesecondoneisaletterrangingfromAtoZexcepttheletterI.Thethirdandfourthonesarelettersornumbers.Thefifthtoseventhonesarenumbersrangingfrom0to9only.Howeverthefirstortheseventhonesmayberedcharactersinspecialplates（asshowninFig.1）.Aftersegmentationprocesstheindividualcharacterisextracted.Takingadvantageofthelayoutandcolorcollocationpriorknowledge,theindividualcharacterwillenteroneoftheclasses:

abbreviationsofChineseprovincesset,lettersset,lettersornumbersset,numberset,specialcharactersset.

Letter

Chinesecharacter

辽BA9083

Number

Letter ornumber

（a）Typicallayout

Letter

Chinesecharacter

辽BB092警

Specialredcharacter

Letter ornumber

（b）Specialcharacter

Fig.1ThelayoutoftheChineselicenseplate

III.THEPROPOSEDALGORITHM

Th