FI GERPRI T VERIFICATIO USI G OPTICAL SHIFTED PHASE- E CODED JOI T TRA SFORM CORRELATIO

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1 FI GEPI VEIFICAIO USI G OPICAL SHIFED PHASE- E CODED JOI A SFOM COELAIO M. azrl Islam Emal: slamn@farmngdale.ed Secrt Sstems Farmngdale State Unerst of New York 350 Broad Hollow oad Farmngdale New York Abstract: Atomatc fngerprnt erfcaton s an mportant tool of an secrt and montorng sstems. An optcal ont transform correlaton technqe s proposed for effcent real-tme recognton of fngerprnts. he proposed technqe emplos optcal lenses and spatal lght modlators to process the gen mages and hence t can eld the erfcaton decson almost nstantaneosl. he optcal correlator s modfed b ncorporatng phase shftng and phase encodng of the reference fngerprnt to aod nnecessar correlaton sgnals and hence make the best tlzaton of the space and bandwdth resorces. he gen npt mage of fngerprnt s correlated drectl wth the reference fngerprnt and a hghl dstncte correlaton sgnal s prodced f the gen fngerprnt s of an athorzed person whle a neglgble correlaton sgnal s prodced for all nathorzed fngerprnts. he proposed technqe s capable of recognzng mltple athorzed fngerprnts smltaneosl n a gen npt scene contanng more than one fngerprnt. Performance of the proposed technqes s nestgated throgh compter smlaton nolng real-lfe fngerprnt mages. e Words: fngerprnt erfcaton ont transform correlaton frnge-adsted flter pattern recognton. I. I ODUCIO Fngerprnt has wdel been tlzed as an effcent bometrc featre to dentf a hman beng. eal-tme atomatc fngerprnt erfcaton s a necessar and er mportant tool for an knd of secrt and montorng applcatons []. Optcal ont transform correlaton (JC) technqe has been obsered to be er effcent for real-tme pattern recognton sstems becase t allows real-tme pdatng of the reference mage permts parallel Forer transformaton of the reference mage and npt scene operates at deo frame rates and elmnates an precse postonng reqrement of comple matched flters n the Forer plane []. Howeer classcal JC technqe sffers from poor correlaton dscrmnaton wde sdelobes par of correlaton for each obect and strong zero-order correlaton. Dfferent algorthms hae been proposed to oercome the lmtatons of the classcal JC technqe namel bnar JC [3] phase-onl JC [4] and frnge-adsted JC [5]. hogh these technqes are able to sole some of the problems mentoned aboe bt the are not as effcent as reqred for practcal real-tme applcatons. A new effcent and sccessfl optcal JC algorthm has been proposed named shfted phaseencoded frnge-adsted JC (SPFJC) technqe [6-7]. It elds a sngle and er dstncte correlaton sgnal wth hgh dscrmnaton between the target mage and the non-target mages and the backgrond and also operates well n nos npt scenes. he obecte of ths paper s to deelop a fngerprnt erfcaton technqe emplong the SPFJC algorthm for atomatc and real-tme applcatons. he reference fngerprnt mage s correlated wth the gen fngerprnt mages and a correlaton sgnal s generated n the otpt plane whch dstngshes a fngerprnt n the database from that not nclded n the database.

2 Compter smlaton s carred to nestgate the performance of the proposed technqe nolng real-lfe fngerprnt mages. II. A ALYSIS Fgre shows the block dagram of the proposed optcal shfted phase-encoded frnge-adsted ont transform correlaton (SPFJC) technqe for dstorton-narant fngerprnt erfcaton sstem. he reference fngerprnt mage r( ) from the database s frst Forer transformed and mltpled b a random phase mask φ( ) as gen b ( ) ( ) ( ) [ ] ( ) r ep () where and are mtall ndependent freqenc doman arables ( ) and r ( ) are the ampltde and phase respectel of the Forer transform of r( ) and ( ) s the Forer transform of φ( ). Inerse Forer transformaton of Eq. () elds the phase-encoded reference mage whch s then fed nto two parallel channels where one channel ntrodces a 80 degree phase shft. Net the npt scene contanng one or more nknown fngerprnt mages t ( ) s now ntrodced to both the channels to form two ont mages as gen b t r f φ () t r f φ (3) where s the nmber of fngerprnt mages n the npt scene. From the Forer transformaton of the aboe eqatons we can obtan two ont power spectra (JPS) as gen b ( ) ( ) F (4) ( ) ( ) F (5) It can be obsered from the aboe eqatons that both the JPS sgnals contan a nmber of terms to prodce ato-correlaton and cross-correlaton terms n the otpt plane. Howeer the followng operaton wll elmnate the nnecessar correlaton sgnals atomatcall where the JPS n Eq. (5) s sbtracted from that n Eq. (4) and the resltant sgnal s mltpled agan b the same phase mask sed earler. hs we get the modfed JPS as

3 [ ] ( ) ( ) F( ) F ( ) P (6) he fnal correlaton sgnal can be obtaned b takng nerse Forer transformaton of Eq. (6). It ma be noted that the frst term n the aboe eqaton wll prodce a correlaton whch wll be scattered n aros drectons n space becase of the random natre of the phase mask. herefore ltmatel onl the second term wll prodce a sngle correlaton sgnal per each potental target fngerprnt n the otpt plane. ( ) ( ) ( ) ( ) ( ) Net a modfed frnge-adsted flter (FAF) s also deeloped to enhance the correlaton performance of the technqe. he flter transfer fncton can be epressed as C ( ) ( ) H (7) D ( ) ( ) where C() and D() are ether constants or fnctons of and. he parameter C() s sed to aod hang an optcal gan greater than nt whle D() s sed to oercome the pole problem. Snce the power spectra of the reference fngerprnt can be pre-calclated and stored ncorporaton of FAF n the proposed technqe wll not adersel mpact the processng speed. hereafter the JPS as gen n Eq. (6) s mltpled b the FAF transfer fncton as gen b Eq. (7) to eld an enhanced JPS whose nerse Forer transformaton wll fnall reslt n a sngle and er sharp correlaton peak for each potental target fngerprnt present n the gen npt scene. III. SIMULAIO ESULS Performance of the proposed fngerprnt erfcaton technqe s ealated sng a compter smlaton program deeloped n MALAB software and emplong a set of real-lfe fngerprnt mages. Fgre shows the correlaton performance sng a sample fngerprnt as the reference mage for the SPFJC technqe. he same fngerprnt s emploed n the npt scene and the resltant correlaton otpt shown n Fg. clearl erfes the effcenc of the technqe becase t generates a er sharp and hghl dstncte correlaton peak. hen a dfferent erson of the same target fngerprnt recorded at a dfferent tme s ntrodced nto the npt scene as shown n Fg. 3. hogh the npt mage ares sgnfcantl from the reference mage n the database bt the proposed technqe s obsered to be er sccessfl n recognzng the fngerprnt b prodcng a dstnct correlaton peak as shown n Fg. 3. Now a non-target fngerprnt s emploed n the npt scene as shown n Fg. 4. he correlaton sgnals n Fg. 4 reects the fngerprnt b generatng nos sgnal where there s no dstncte peak. Net the proposed technqe s nestgated emplong an npt scene shown n Fg. 5 whch contans mltple fngerprnt mages among whch two are potental target fngerprnts. he correlaton otpt n Fg. 5 shows two sharp peaks correspondng to the target fngerprnts

4 whle reectng all non-target fngerprnts. Fnall an npt scene s consdered n the smlaton whch s corrpted b nose as shown n Fg. 6. he correlaton otpt n Fg. 6 confrms that the proposed technqe s er effcent and sccessfl n erfng the target fngerprnts een n nos enronment. Smlar other nestgatons are carred ot wth other fngerprnt mages and n dfferent practcal scenaros where n eer case the proposed technqe s obsered to perform ecellent. IV. CO CLUSIO An effcent and hgh-speed fngerprnt erfcaton technqe s proposed n ths paper. he proposed technqe s obsered to be er sccessfl n recognzng a target fngerprnt whch s nclded n the database and reect an other fngerprnts. It prodces an effcent correlaton otpt whch clearl dentfes the target fngerprnts. he technqe s also capable of dentfng mltple fngerprnts n the same npt scene smltaneosl. Compter smlaton reslts erf the effecteness of the technqe n dfferent practcal real-lfe scenaro lke nos scenes. Optcal mplementaton of the technqe wll eld a real-tme fngerprnt erfcaton sstem for secrt applcatons. EFEE CES [] S. Prabhakar and A.. Jan Decson-leel fson n fngerprnt erfcaton Pattern ecognton ol. 35 pp [] C. S. Weaer and J. W. Goodman echnqe for optcall conolng two fnctons Appled Optcs ol. 5 pp [3] B. Jad and C. o Jont transform mage correlaton sng a bnar spatal lght modlator at the Forer plane Appled Optcs ol. 7 pp [4] A.. Cherr and M. S. Alam eference phase-encoded frnge-adsted ont transform correlaton Appled Optcs ol. 40 pp [5] M. S. Alam and M. A. arm Frnge-adsted ont transform correlaton Appled Optcs ol. 3 pp [6] M.. Hader M. N. Islam M. S. Alam and J. F. han Shfted phase-encoded frngeadsted ont transform correlaton for mltple target detecton Optcs Commncatons ol. 48 pp [7] M.. Hader M. N. Islam and M. S. Alam Enhanced class assocate generalzed frngeadsted ont transform correlaton for mltple target detecton Optcal Engneerng ol. 45 no. 4 pp

5 Phase Mask Forer ransform eference Fngerprnt from Database Forer ransform Inerse Forer ransform 80 0 Phase Shft Forer ransform Inpt Scene Phase Mask Jont Power Spectrm Correlaton Otpt Inerse Forer ransform Frnge- Adsted Flter Jont Power Spectrm Fgre : Block dagram of shfted phase-encoded frnge-adsted ont transform correlaton technqe (a) Fgre : Correlaton performance sng a target fngerprnt: (a) reference fngerprnt from database npt fngerprnt correlaton otpt

6 (a) Fgre 3: Correlaton performance sng a target fngerprnt whch s recorded at dfferent tme: (a) reference fngerprnt npt fngerprnt correlaton otpt (a) Fgre 4: Correlaton performance sng a non-target fngerprnt: (a) reference fngerprnt npt fngerprnt correlaton otpt

7 (a) Fgre 5: Correlaton performance wth an npt scene hang mltple fngerprnts: (a) reference fngerprnt npt scene correlaton otpt

8 (a) Fgre 6: Correlaton performance wth an npt scene hang mltple fngerprnts and corrpted b nose: (a) reference fngerprnt npt scene correlaton otpt