A study of segmentation and normalization for iris recognition

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1、AStudyofSegmentationandNormalizationforIrisRecognitionSystemsbyEhsanM.ArvachehAthesispresentedtotheUniversityofWaterlooinful¯llmentofthethesisrequirementforthedegreeofMasterofAppliedScienceinSystemsDesignEngineeringWaterloo,Ontario,Canada,2006°cEhsan

2、M.Arvacheh2006IherebydeclarethatIamthesoleauthorofthisthesis.Thisisatruecopyofthethesis,includinganyrequired¯nalrevisions,asacceptedbymyexaminers.Iunderstandthatmythesismaybemadeelectronicallyavailabletothepublic.EhsanM.ArvachehiiAbstractIrisrecognit

3、ionsystemscaptureanimagefromanindividual'seye.Theirisintheimageisthensegmentedandnormalizedforfeatureextractionprocess.Theperformanceofirisrecognitionsystemshighlydependsonsegmentationandnormalization.Forinstance,evenane®ectivefeatureextractionmethod

4、wouldnotbeabletoobtainusefulinformationfromanirisimagethatisnotsegmentedornormalizedproperly.Thisthesisistoenhancetheperformanceofsegmentationandnormalizationprocessesinirisrecognitionsystemstoincreasetheoverallaccuracy.Thepreviousirissegmentationapp

5、roachesassumethattheboundaryofpupilisacircle.However,accordingtoourobservation,circlecannotmodelthisboundaryaccurately.Toimprovethequalityofsegmentation,anovelactivecontourisproposedtodetecttheirregularboundaryofpupil.Themethodcansuccessfullydetectal

6、lthepupilboundariesintheCASIAdatabase[42]andincreasetherecognitionaccuracy.Mostpreviousnormalizationapproachesemploypolarcoordinatesystemtotransformiris.Transformingirisintopolarcoordinatesrequiresareferencepointasthepolarorigin.Sincepupilandlimbusar

7、egenerallynon-concentric,therearetwonaturalchoices,pupilcenterandlimbuscenter.However,theirperformancedi®erenceshavenotbeeninvesti-gatedsofar.Wealsoproposeareferencepoint,whichisthevirtualcenterofapupilwithradiusequaltozero.Wereferthispointasthelinea

8、rly-guessedcenter.Theexperimentsdemonstratethatthelinearly-guessedcenterprovidesmuchbetterrecognitionaccuracy.Inadditiontoevaluatingthepupilandlimbuscentersandproposinganewrefer-encepointfornormalization,wereformulatethenormalizationproblemasaminimiz