ΑΡΙΣΤΟΤΕΛΕΙΟ ΠΑΝΕΠΙΣΤΗΜΙΟ ΘΕΣΣΑΛΟΝΙΚΗΣ ΣΧΟΛΗ ΘΕΤΙΚΩΝ ΕΠΙΣΤΗΜΩΝ ΤΜΗΜΑ ΠΛΗΡΟΦΟΡΙΚΗΣ

ΑΡΙΣΤΟΤΕΛΕΙΟ ΠΑΝΕΠΙΣΤΗΜΙΟ ΘΕΣΣΑΛΟΝΙΚΗΣ ΣΧΟΛΗ ΘΕΤΙΚΩΝ ΕΠΙΣΤΗΜΩΝ ΤΜΗΜΑ ΠΛΗΡΟΦΟΡΙΚΗΣ ΜΑΡΙΟΥ ΚΥΠΕΡΟΥΝΤΑ Ηλεκτρολόγου Μηχανικού, Διπλωματούχου Μεταπτυχιακών Σπουδών ΤΕΧΝΙΚΕΣ ΨΗΦΙΑΚΗΣ ΕΠΕΞΕΡΓΑΣΙΑΣ ΕΙΚΟΝΑΣ ΜΕ ΕΦΑΡΜΟΓΕΣ ΣΤΙΣ ΑΝΘΡΩΠΟΚΕΝΤΡΙΚΕΣ ΔΙΕΠΑΦΕΣ ΚΑΙ ΤΗΝ ΑΝΑΛΥΣΗ ΒΙΝΤΕΟ ΔΙΔΑΚΤΟΡΙΚΗ ΔΙΑΤΡΙΒΗ Θεσσαλονίκη 2010

ΜΑΡΙΟΥ ΚΥΠΕΡΟΥΝΤΑ ΤΕΧΝΙΚΕΣ ΨΗΦΙΑΚΗΣ ΕΠΕΞΕΡΓΑΣΙΑΣ ΕΙΚΟΝΑΣ ΜΕ ΕΦΑΡΜΟΓΕΣ ΣΤΙΣ ΑΝΘΡΩΠΟΚΕΝΤΡΙΚΕΣ ΔΙΕΠΑΦΕΣ ΚΑΙ ΤΗΝ ΑΝΑΛΥΣΗ ΒΙΝΤΕΟ ΔΙΔΑΚΤΟΡΙΚΗ ΔΙΑΤΡΙΒΗ Υποβλήθηκε στο Τμήμα Πληροφορικής, Τομέας Ψηφιακών Μέσων Ημερομηνία Προφορικής Εξέτασης: 27 Ιανουαρίου, 2010 Εξεταστική Επιτροπή Καθηγητής Ι. Πήτας, Επιβλέπων Αναπλ. Καθηγητής Κ. Κοτρόπουλος, Μέλος Τριμελούς Συμβουλευτικής Επιτροπής Αναπλ. Καθηγήτρια Α. Βακάλη, Μέλος Τριμελούς Συμβουλευτικής Επιτροπής Καθηγητής Ι. Βλαχάβας, Εξεταστής Ερευνητής Β Δ. Τζοβάρας, Εξεταστής Ερευνητής Β Σ. Μαλασιώτης, Εξεταστής Λέκτορας Α. Τέφας, Εξεταστής

Μάριου Κυπερούντα Α.Π.Θ. ΤΕΧΝΙΚΕΣ ΨΗΦΙΑΚΗΣ ΕΠΕΞΕΡΓΑΣΙΑΣ ΕΙΚΟΝΑΣ ΜΕ ΕΦΑΡΜΟΓΕΣ ΣΤΙΣ ΑΝΘΡΩΠΟΚΕΝΤΡΙΚΕΣ ΔΙΕΠΑΦΕΣ ΚΑΙ ΤΗΝ ΑΝΑΛΥΣΗ ΒΙΝΤΕΟ ISBN «Η έγκριση της παρούσης Διδακτορικής Διατριβής από το Τμήμα Πληροφορικής του Αριστοτελείου Πανεπιστημίου Θεσσαλονίκης δεν υποδηλώνει αποδοχή των γνωμών του συγγραφέως» (Ν. 5343/1932, άρθρο 202, παρ. 2)

me apèranth ag ph kai eugnwmosônh, stouc goneðc mou, 'Akh kai LugÐa, ston aderfì kai aderf mou, SpÔro kai GewrgÐa, kai sthn arrabwniastiki mou, Qrust lla.

PROLOGOS H ergasða aut apoteleð thn didaktorik diatrib tou M riou KuperoÔnta kai ekpon jhke kat kôrio lìgo sto Ergast rio Teqnht c NohmosÔnhc kai An lushc Plhrofori n tou Tm matoc Plhroforik c tou AristoteleÐou PanepisthmÐou JessalonÐkhc. H ereunhtik ergasða xekðnhse ton Ianou rio tou 2004 upì thn epðbleyh tou kajhght tou tm matoc Plhroforik c A.P.J., k. Iw nnh P ta kai me mèlh thc trimeloôc sumbouleutik c epitrop c touc kajhghtèc tou tm matoc Plhroforik c A.P.J., k. KwnstantÐno Kotrìpoulo kai k. Ajhn Bak lh. H ergasða pou parousi zetai se aut thn didaktorik diatrib proèkuye met apì shmantikì kìpo, anaz thsh kai melèth tou suggrafèa all kai me thn polôtimh sumbol poll n llwn anjr pwn. Ja jela na euqarist sw jerm ton epiblèponta kajhght tou didaktorikoô kai kajhght tou Tm matoc Plhroforik c A.P.J., k. Iw nnh P ta gia thn polôtimh kajod ghs tou, tic anex ntlhtec gn seic tou, thn suneq sunergasða tou mazð mou kaj c kai thn paroq twn mèswn tou ergasthrðou kat th di rkeia ekpìnhshc thc diatrib c. Ja jela epðshc na euqarist sw jerm kai touc llouc dôo kajhghtèc tou Tm matoc Plhroforik c A.P.J. kai mèlh thc trimeloôc sumbouleutik c mou epitrop c, k. KwnstantÐno Kotrìpoulo, o opoðoc epèbleye thn ergasða pou parousi zetai sto pèmpto kef laio dðnontac polôtimec sumboulèc, kai k. Ajhn Bak lh, gia thn exðsou shmantik sumbol kai enj rruns touc. Ja jela akìma na euqarist sw ton lèktora k. Anast sio Tèfa pou me tic polôtimec sumboulèc tou èdwse shmantik jhsh sthn prìodo thc ergasðac. EpÐshc, ja jela na euqarist sw gia thn polôtimh sunergasða kai antallag apìyewn, ìla ta mèlh tou ErgasthrÐou Teqnht c NohmosÔnhc kai An lushc Plhrofori n tou Tm matoc Plhroforik c A.P.J., tèwc kai nun: ton k. Ge rgio Goudèlh, th Dr. Eir nh K tsia, to Dr. Miqa l KrhnÐdh, ton k. Z nwna JeodosÐou, thn k. Zuzana Cernekova, to Dr. M rio GabrihlÐdh, ton epðkouro kajhght tou Tm matoc Plhroforik c A.P.J. k. Nikìlao Nikolaòdh, ton lèktora k. Nikìlao L skarh, kaj c kai ìla ta upìloipa mèlh tou ergasthrðou. JessalonÐkh, 2010

PERILHYH Ta genikìtera antikeðmena ta opoða pragmateôetai h didaktorik diatrib eðnai oi teqnikèc epexergasðac eikìnac kai teqnht c nohmosônhc gia thn anagn rish pros pou, thn epibebaðwsh tautìthtac pros pou, thn taxinìmhsh ekfr sewn pros pou, kai thn anðqneush enallag c skhn n se bðnteo. Arqik, proteðnetai mia teqnik anagn rishc pros pou h opoða stìqo èqei na anagnwrðsei thn tautìthta enìc upì dokim pros pou epilôontac èna sônolo aplousteumènwn problhm twn taxinìmhshc. Autì gðnetai efarmìzontac dunamik ekpaðdeush se èna sq ma polustadiak c omadopoðhshc, sto opoðo dhmiourgoôntai diakritikèc om dec. H dunamik ekpaðdeush epitrèpei th dhmiourgða miac seir c upoq rwn pou eðnai eidikoð ìson afor to upì taxinìmhsh prìswpo, gegonìc pou enisqôei shmantik thn apìdosh thc mejìdou. EpÐshc, proteðnetai mða teqnik epibebaðwshc tautìthtac pros pou, h opoða efarmìzei pollaplèc grammikèc diakritikèc analôseic se tm mata qarakthristik n dianusm twn omoiìthtac kai stajmðzei ta diakritik uperepðpeda pou prokôptoun. H teqnik aut periorðzei ta probl mata pou dhmiourgoôntai lìgw mh eparkoôc arijmoô deigm twn ekpaðdeushc kai h anamenìmenh ikanìthta taxinìmhshc thc exet zetai mèsw miac seir c prosomoi sewn. AkoloÔjwc, orðzontai oi kat llhloi, kai eidikoð gia k je prìswpo, sunduasmoð bajmologi n omoiìthtac pou enisqôoun thn ikanìthta epibebaðwshc pros pou. Epiplèon, proteðnetai mia teqnik taxinìmhshc ekfr sewn pros pou h opoða lônei pollapl probl mata taxinìmhshc dôo kl sewn, epilog gia thn opoða paratðjetai majhmatik epiqeirhmatologða. AkoloÔjwc, k nontac qr sh enìc mètrou diaqwrismoô kl sewn, efarmìzetai mia epanalhptik diadikasða ìpou ex gontai uyhl c poiìthtac qarakthristik. AkoloÔjwc, anaptôssetai èna sq ma taxinìmhshc ìpou se k je b ma tou entopðzetai kai qrhsimopoieðtai o pio axiìpistoc taxinomht c kai, sunep c, prokôptei mia pio akrib c telik apìfash taxinìmhshc. Tèloc, proteðnetai ènac algìrijmoc anðqneushc enallag c skhn n bðnteo pou dhmiourgeð èna sônolo beltiwmènwn idioakoustik n plaisðwn ta opoða antistoiqoôn se upoq ro ìpou oi allagèc akoustikoô upìbajrou entopðzontai eôkola. Epiplèon, qrhsimopoioôntai optikèc plhroforðec me stìqo thn eujugr mmish twn endeðxewn enallag c akoustik n skhn n me tic geitonikèc enallagèc pl nwn bðnteo. EpÐshc, entopðzontai sugkekrimèna efè tou bðnteo pou upodeiknôoun enallagèc skhn n. Gia megalôterh akrðbeia, oi endeðxeic enallag c skhn n epikur nontai me thn exagwg poikðlwn akoustik n qarakthristik n.

IMAGE PROCESSING TECHNIQUES FOR HUMAN-CENTERED INTERACTION AND FOR VIDEO ANALYSIS SUMMARY The main research focus of this dissertation pertains to developing novel image processing and artificial intelligence techniques in order to perform face recognition, face verification, facial expression classification, and scene change detection in video sequences. Initially, a face recognition method is proposed, which aims to determine the identity of a test face by solving a number of simplified classification problems. This is achieved by applying dynamic training to a multi-step clustering scheme, during which discriminant clusters are created. The dynamic training allows creating a set of test-face-specific subspaces, which improves performance. Next, a face verification method is proposed. It applies a piecewise linear discriminant analysis process on similarity feature vectors and properly weighs the resulting discriminant hyper-planes. This method curbs problems related to insufficient numbers of training data and its expected classification performance is investigated via a series of simulations. Then, proper combinations of the various similarity scores are determined and used to produce a more accurate decision. In addition, a facial expression classification method is proposed. It operates by solving a number of two-class problems, a choice that is analytically justified. Then, it makes use of a class separability measure and applies an iterative process in order to extract high-quality features. Next, a classification scheme is developed where, during each of its steps, the most reliable classifier is identified and used in order to produce an more accurate decision. Lastly, a scene change detection method is proposed. It produces a set of enhanced eigen-audioframes that relate to a subspace where background noise changes are easily detected. Moreover, visual information is employed in order to align the audio scene change indications to neighboring video shot changes. In addition, certain video special-effects that are commonly used during scene changes are detected. By using various acoustic features to verify the scene change indications, the accuracy of this method increases further.

Kef laia BiblÐwn DHMOSIEUSEIS 1. M. Kyperountas, A. Tefas, and I. Pitas, Discriminant learning in large databases using training space partitioning, in Advances in Face Image Analysis - Techniques and Technologies, Ed. Yu-Jin Zhang. Pennsylvania: IGI Global, in press, accepted Aug. 2009. 'Arjra se Episthmonik Periodik 1. M. Kyperountas, A. Tefas, and I. Pitas, Weighted piecewise LDA for solving the small sample size problem in face verification, IEEE Transactions on Neural Networks, vol. 18, no. 2, pp. 506-519, March 2007. 2. M. Kyperountas, C. Kotropoulos and I. Pitas, Enhanced eigen-audioframes for audiovisual scene change detection, IEEE Transactions on Multimedia, vol. 9, no. 4, pp. 785-797, June 2007. 3. M. Kyperountas, A. Tefas, and I. Pitas, Dynamic training using multistage clustering for face recognition, Pattern Recognition Journal, Elsevier, vol. 41, no. 3, pp. 894-905, March 2008. 4. M. Kyperountas, A. Tefas, and I. Pitas, Salient feature and reliable classifier selection for facial expression classification, Pattern Recognition Journal, Elsevier, accepted June 2009.

'Arjra se Episthmonik Sunèdria 1. M. Kyperountas, Z. Cernekova, C. Kotropoulos, M. Gavrielides, and I. Pitas, Audio PCA in a novel multimedia scheme for scene change detection, in Proc. IEEE Int. Conf. on Acoustics, Speech, and Signal Processing (ICASSP 2004), Montreal, May 2004. 2. M. Kyperountas, Z. Cernekova, C. Kotropoulos, M. Gavrielides, and I. Pitas, Scene change detection using audiovisual clues, in Proc. of Norwegian Conference on Image Processing and Pattern Recognition (NOBIM 2004), Stavanger, Norway, 27-28 May 2004. 3. M. Kyperountas, A. Tefas, and I. Pitas, Methods for improving discriminant analysis for face authentication, in Proc. IEEE Int. Conf. on Acoustics, Speech, and Signal Processing (ICASSP 2005), Philadelphia, March 2005. 4. M. Kyperountas, A. Tefas, and I. Pitas, Face verification using locally linear discriminant models, in Proc. IEEE Int. Conf. on Image Processing (ICIP 2007), vol. 4, pp. 469-472, San Antonio, 16-19 Sep., 2007. 5. M. Kyperountas, A. Tefas, and I. Pitas, Face recognition via adaptive discriminant clustering, in Proc. IEEE Int. Conf. on Image Processing (ICIP 2008), pp. 2744-2747, San Diego, Oct. 2008. 6. M. Kyperountas and I. Pitas, Facial expression recognition using two-class discriminant features, Springer Lecture Notes in Computer Science: Biometric ID Management and Multimodal Communication, pp. 89-96, Sep. 2009. 7. M. Kyperountas, A. Tefas, and I. Pitas, Pairwise facial expression classification, in Proc. IEEE International Workshop on Multimedia Signal Processing (MMSP 2009), pp. 1-4, Rio de Janeiro, Brazil, Oct. 2009.

Perieqìmena 1 Eisagwg 1 2 Anagn rish Tautìthtac Pros pou 9 2.1 Eisagwg.................................. 9 2.1.1 Episkìphsh teqnik n....................... 10 2.1.2 MejodologÐa Dunamik c EkpaÐdeushc gia Polustadiak OmadopoÐhsh............................... 12 2.1.3 Sumbol kai dom tou kefalaðou................. 13 2.2 Epilog qarakthristik n kai h dom tou DTMC............ 14 2.2.1 EÔresh twn MDF q rwn mèsw tou RLDA............ 15 2.2.2 H mèjodoc omadopoðhshc k-mèswn................ 16 2.2.3 MeÐwsh tou plhj rijmou tou sunìlou ekpaðdeushc me thn efarmog mètrou pou basðzetai sthn entropða............ 16 2.3 H mejodologða anagn rishc pros pou DTMC............. 18 2.3.1 Algìrijmoc DTMC: B ma 1.................... 18 2.3.2 Algìrijmoc DTMC: B ma 2.................... 18 2.3.3 Algìrijmoc DTMC: B ma 3.................... 19 2.3.4 Algìrijmoc DTMC: B ma 4.................... 19 2.3.5 Antimet pish meg lwn diataxik n diakum nsewn........ 22 2.3.6 Epanalhptik diergasða...................... 23 2.4 Peiramatik axiolìghsh tou DTMC................... 24 2.4.1 EktÐmhsh katwflioô kai paramètrou omalopoðhshc qrhsimopoi ntac th b sh dedomènwn UMIST............... 25 2.4.2 Axiolìghsh thc apìdoshc se sqèsh me ton diajèsimo arijmì deigm twn ekpaðdeushc an tomo (N T ), qrhsimopoi ntac tic b seic dedomènwn ORL kai XM2VTS............... 26 xi

xii PERIEQ OMENA 2.4.3 Axiolìghsh thc apìdoshc se sqèsh me ton diajèsimo arijmì deigm twn ekpaðdeushc an tomo (N T ) kai ton arijmì twn atìmwn (Y ), qrhsimopoi ntac th b sh dedomènwn FERET..... 33 2.5 Sumpèrasma................................. 37 3 EpibebaÐwsh Tautìthtac Pros pou 45 3.1 Eisagwg.................................. 45 3.1.1 Episkìphsh teqnik n....................... 47 3.1.2 Mèjodoc Stajmismènhc Tmhmatik cgrammik c Diakritik c An - lushc pollapl n bajmologð n.................. 50 3.1.3 Sumbol kai dom tou kefalaðou................. 51 3.2 Perigraf probl matoc.......................... 52 3.3 Endun mwsh Grammik c Diakritik c An lushc............. 53 3.3.1 Montèlo Stajmismènhc Tmhmatik c Grammik c Diakritik c An - lushc................................ 54 3.3.2 EpanektÐmhsh twn elattwmatik n diakritik n suntelest n.. 55 3.3.3 St jmish twn pollapl n bajmologi n taxinìmhshc...... 57 3.4 Prosomoiwmèna kai empeirik apotelèsmata............... 58 3.4.1 Apìdosh taxinìmhshc se prosomoiwmèna dedomèna....... 58 3.4.2 Diakritik qarakthristik upì to prìblhma SSS........ 63 3.4.3 Axiolìghsh mejìdou stic b seic dedomènwn M2VTS kai XM2VTS 67 3.5 Sumpèrasma................................. 75 4 Taxinìmhsh Ekfr sewn Pros pou 81 4.1 Eisagwg.................................. 81 4.1.1 Episkìphsh teqnik n....................... 82 4.1.2 MejodologÐa Epilog c Shmantikìterwn Qarakthristik n kai Axiìpistwn Taxinomht n..................... 84 4.1.3 Sumbol kai dom tou kefalaðou................. 86 4.2 SÔgkrish mejìdwn LDA.......................... 87 4.2.1 LDA pollapl n kl sewn ènanti LDA dôo kl sewn....... 88 4.2.2 LDA mðac-enantðon-ìlwn ènanti LDA dôo kl sewn....... 94 4.2.3 SÔgkrish upologistikoô kìstouc mejìdwn LDA......... 96 4.3 DhmiourgÐa SFV kai SDH......................... 98 4.3.1 Exagwg Gabor qarakthristik n................. 98 4.3.2 Mètro diaqwrisimìthtac kl sewn gia epilog qarakthristik n 99 4.3.3 DhmiourgÐa SFV gia thn paragwg SDH............. 101

PERIEQ OMENA xiii 4.4 Taxinìmhsh mèsw epilog c axiìpistou taxinomht............ 103 4.4.1 Proswrinì Sq ma Taxinìmhshc (ICS).............. 105 4.4.2 Sq ma taxinìmhshc Epilog c Axiìpistwn Taxinomht n (RCS). 106 4.5 Peiramatik apotelèsmata......................... 110 4.6 Sumpèrasma................................. 119 5 AnÐqneush Enallag c Skhn n 125 5.1 Eisagwg.................................. 125 5.1.1 Episkìphsh teqnik n....................... 128 5.1.2 Optikoakoustik anðqneush b sei beltiwmènwn idioakoustik n plaisðwn............................... 131 5.1.3 Sumbol kai dom tou kefalaðou................. 132 5.2 Idioakoustik plaðsia gia anðqneush enallag c skhn n......... 133 5.3 Epilog bèltistou upoq rou akoustikoô s matoc............ 141 5.4 EnopoÐhsh akoustik c kai optik c plhroforðac............. 147 5.4.1 EpikÔrwsh endeðxewn enallag c skhn n............. 149 5.5 Peiramatik apotelèsmata......................... 151 5.6 Sumpèrasma................................. 159 6 Sumper smata 165 6.1 Mellontik èreuna............................. 168

Kef laio 1 Eisagwg Ta teleutaða qrìnia, èqei parousiasteð auxhmèno endiafèron sthn ereunhtik koinìthta ìson afor thn an ptuxh autìmatwn biometrik n teqnologi n, ìpwc eðnai h anagn rish kai h epibebaðwsh tautìthtac pros pou. Sta sust mata anagn rishc pros pou, anazhtoôntai, mèsa apì mia seir pros pwn anafor c N, ta prìswpa ekeðna pou parousi zoun tic perissìterec omoiìthtec me to upì taxinìmhsh prìswpo. Sta sust mata epibebaðwshc tautìthtac pros pou, èna upì taxinìmhsh prìswpo sugkrðnetai me èna prìswpo anafor c. H sôgkrish odhgeð se jetikì apotèlesma an h tautìthta tou upì taxinìmhsh pros pou eðnai Ðdia me thn tautìthta tou pros pou anafor c (dhl. to upì taxinìmhsh prìswpo antistoiqeð se pel th), se arnhtikì apotèlesma (dhl. to upì taxinìmhsh prìswpo antistoiqeð se k poion apate na). H anagn rish kai h epibebaðwsh tautìthtac pros pou qrhsimopoioôntai susthmatik gia lìgouc asf leiac tìso ston emporikì ìso kai sto dhmìsio tomèa (p.q. dhmosða t xh). Sto dhmìsio tomèa, oi teqnologðec autèc mporoôn na bohj soun sth gr gorh tautopoðhsh enìc upìptou, to prìswpo tou opoðou èqei fwtografhjeð binteoskophjeð kat th di rkeia di praxhc enìc egkl matoc. Akìmh, mporoôn na qrhsimopoihjoôn gia thn anagn rish atìmou to opoðo ja mporoôse na eðnai epikðnduno gia to eurô koinì, ìpwc p.q. k poiou tromokr th, se sqedìn pragmatikì qrìno. Ston emporikì tomèa, mporoôn na dhmiourg soun èna nèo eðdoc fikleidioôfl, me thn topojèthsh fwtografi n se pistwtikèc kai qrewstikèc k rtec. Epiplèon, qrhsimopoi ntac autèc tic teqnologðec, mia apl binteok mera ja mporoôse na energ sei wc frourìc asf leiac, prosfèrontac dunatìthta eisìdou mìno se toma ta opoða epibebai nontai wc gnwst. EpÐshc, oi stìqoi gia touc opoðouc qrhsimopoioôntai ta sust mata anagn rishc epibebaðwshc tautìthtac pros pou, kai ekfr sewc pros pou, èqoun 1

2 KEF ALAIO 1. EISAGWG H exeliqjeð peraitèrw ta teleutaða qrìnia. Merikèc apì tic nèec efarmogèc eðnai h ermhneða twn anjr pinwn projèsewn kai sumperifor n me stìqo na prokatal boun sugkekrimènec enèrgeiec oi opoðec mporeð, pijan c, na eðnai epikðndunec. EÐnai gnwstì ìti di foroi eidikoð asf leiac èqoun proteðnei ton entopismì sugkekrimènwn sumperifor n, ìpwc p.q. flblèmma sto peirofl, wc mèjodo anagn rishc pijan n tromokrat n amèswc prin mða tromokratik enèrgeia. Genik, èqei anaptuqjeð meg loc arijmìc mejìdwn pou èqoun c stìqo thn taxinìmhsh pros pwn, ìpou sun jwc efarmìzontai statistik krit ria, gewmetrik krit ria, neurwnik dðktua. H taxinìmhsh ekfr sewn pros pou apoteleð mia trðth idiaitèrwc qr simh biometrik teqnologða. Skopìc twn susthm twn taxinìmhshc ekfr sewn pros pou eðnai na metr soun touc bajmoôc omoiìthtac thc ekfr sewc tou upì taxinìmhsh pros pou me di forec prokajorismènec ekfr seic. H teqnologða aut qrhsimopoieðtai se di - forec efarmogèc, ìpwc aut thc eikonik c pragmatikìthtac ìpou pragmatopoieðtai klwnopoðhsh twn ekfr sewn tou pros pou, thc eikonodi skeyhc ìpou mporeð na apaiteðtai an ptuxh autìmatwn anjrwpokentrik n diepaf n. EpÐshc, mporeð na qrhsimopoihjeð se efarmogèc dhmiourgðac profðl, eurethriasmoô, an kthshc qr sth apì b seic dedomènwn eikìnac bðnteo. H anagn rish ekfr sewn pros pou mporeð na gðnei eðte me thn efarmog exagwg c qarakthristik n tou pros pou me th qrhsimopoðhsh montèlwn-protôpwn. Sugkekrimèna, oi mèjodoi pou basðzontai sthn exagwg qarakthristik n qrhsimopoioôn gewmetrik plhroforða plhroforða uf c prokeimènou na prokôyei h apìfash taxinìmhshc. Antijètwc, oi upìloipec mèjodoi pou qrhsimopoioôn montèla-prìtupa taxinomoôn mða èkfrash qrhsimopoi ntac disdi stata akìmh kai trisdi stata montèla kefalioô kai pros pou. EÐnai gnwstì pwc h autìmath anagn rish ekfr sewn pros pou apoteleð prìklhsh afoô o trìpoc ekfr sewc poll n ekfr sewn eðnai upokeimenikìc. Dhlad, o k je njrwpoc èqei to dikì tou trìpo èkfrashc sugkekrimènwn sunaisjhm twn. Sunep c, ìson afor thn èreuna gia thn autìmath anagn rish ekfr sewn pros pou, h prosp jeiec èqoun epikentrwjeð se orismènec, mìno, ekfr seic oi opoðec eðnai, sun jwc, diakritèc. Genik, h autìmath an lush pros pwn parousi zei mia shmantik prìklhsh. Ta anjr pina prìswpa èqoun parìmoia dom, me tic dia-proswpikèc diaforèc na eðnai deutereôousac shmasðac. Epiplèon, oi poikðlec phgèc fwtismoô kai oi di foroi prosanatolismoð pros pou periplèkoun peraitèrw tic diadikasðec an lushc pros pou, dhmiourg ntac ètsi èna apì ta duskolìtera probl mata an lushc protôpwn. 'Ena epiplèon prìblhma afor th mh epark di jesh deigm twn, dhl. eikìnwn pros pou, pou mporoôn na qrhsimopoihjoôn gia thn ekpaðdeush twn mejìdwn an lushc pros -

3 pou. Prìsfata, èqoun protajeð di forec mèjodoi me stìqo na xeperastoôn oi proanaferjèntec duskolðec. Ta kentrik probl mata pou antimetwpðzoun oi algìrijmoi autoð aforoôn thn epilog twn kat llhlwn qarakthristik n ètsi ste na gðnei swst ekpros phsh tou pros pou gia skopoôc taxinìmhshc. Pollèc forèc, èna upersônolo qarakthristik n exet zetai me stìqo thn epilog enìc uposunìlou to opoðo na eðnai apotelesmatikì kat tic mellontikèc sugkrðseic me llec eikìnec pros pwn. 'Ena deôtero prìblhma pou lamb netai upìyin eðnai h upologistik poluplokìthta, h opoða prèpei na diathrhjeð se logik plaðsia prokeimènou na up rqei h ligìterh dunat kajustèrhsh mèqri na bgeð h apìfash taxinìmhshc. Kata protðmhsh, o qrìnoc autìc ja prèpei na eðnai tìso mikrìc ètsi ste na mporeð na efarmosteð h mèjodoc se real-time efarmogèc. To pr to b ma gia èna oloklhrwmèno sôsthma anagn rishc tautìthtac pros pou, epibebaðwshc tautìthtac pros pou, taxinìmhshc ekfr sewn pros pou eðnai o entopismìc tou pros pou. Autì mporeð na gðnei entopðzontac thn perðmetro tou pros pou sugkekrimèna qarakthristik tou pros pou. Gia par deigma, entopðzontai ta m tia, h môth, kai to stìma. AfoÔ gðnei autì, tìte mporeð na gðnei kanonikopoðhsh tou pros pou ètsi ste ta qarakthristik enìc sunìlou eikìnwn na brðskontai p nta se sugkekrimènec gewmetrikèc jèseic. Sun jwc, gðnetai kanonikopoðhsh b sh thc jèshc twn mati n. 'Ena deôtero b ma pou mporeð na efarmìzetai apì èna oloklhrwmèno biometrikì sôsthma eðnai h kanonikopoðhsh twn eikìnwn pros pou ìson afor th fwteinìthta thn afaðresh tou jorôbou sthn eikìna. EpÐshc, analìgwc twn dedomènwn ekpaðdeushc, eðnai dunatìn na gðnoun kanonikopoi seic, diorj seic, analìgwc twn qarakthristik n twn pros pwn sta dedomèna ekpaðdeushc. Dhlad, sth f sh aut gðnetai metatrop twn dedomènwn ètsi ste na moi zoun perissìtero sta dedomèna ekpaðdeushc me stìqo èna pio akribèc apotèlesma taxinìmhshc. Gia par deigma, mporeð na gðnei kanonikopoðhsh ìson afor thn hlikða, thn pìza, thn parousða triqofuðac, ìson afor thn apìkruyh mèrouc tou pros pou, gia par deigma, lìgw guali n hlðou k.t.l. Oi diadikasðec entopismoô diìrjwshc pou anafèrontai den aforoôn tic mejìdouc pou proteðnontai se aut th diatrib. EÐnai anamenìmeno ìti ta apotelèsmata twn proteinìmenwn mejìdwn mporoôn na beltiwjoôn peraitèrw me thn efarmog aut n twn diadikasi n. Mia deôterh kathgorða teqnologi n gia thn opoða èqei parathrhjeð mia katakìrufh aôxhsh tou endiafèrontoc, afor thn org nwsh kai an lush optikoakoustik n plhrofori n. O suneq c auxanìmenoc ìgkoc optikoakoustik n dedomènwn èqei faner sei thn an gkh an ptuxhc kat llhlwn algorðjmwn pou sun jwc stoqeôoun sthn

4 KEF ALAIO 1. EISAGWG H omadopoðhsh twn optikoakoustik n dedomènwn se ousi deic kathgorðec, sthn kataq rish aut n twn kathgori n se euret rio kai sthn paroq gr gorhc anaz thshc kai an kthshc plhrofori n. H enswm twsh plhrofori n pou parèqontai apì di forec phgèc mèswn, prokeimènou na antimetwpistoôn polumesikèc anazht seic se meg lec kai poikðlec optikoakoustikèc b seic dedomènwn, apoteleð ton telikì stìqo. H ikanìthta enswm twshc exart tai se meg lo bajmì apì thn kat llhlh kathgoriopoðhsh twn optikoakoustik n plhrofori n se shmasiologikèc (semantic) kl seic, p.q. se skhnèc. Wc apotèlesma, h anðqneush enallag c skhn n eðnai aparaðthth gia thn autìmath kat tmhsh bðnteo pou basðzetai sto perieqìmeno tou. Se arketèc peript seic, ta ìria miac skhn c orðzontai mèsw tou entopismoô diafìrwn protôpwn se mia binteoseir. Ta prìtupa aut kathgoriopoioôntai kai pragmatopoieðtai mða suneq c sôgkrish protôpwn me stìqo na posotikopoihjoôn oi diaforèc ìson afor to perieqìmeno tou bðnteo. 'Otan oi diaforèc autèc megal soun shmantik kai apìtoma, tìte jewreðtai pwc èqei arqðsei mða nèa skhn. To proanaferjèn perieqìmeno mporeð na eðnai optikì akoustikì, ènac sunduasmìc twn dôo. Gia par deigma mia skhn mporeð na parousi zei mða suz thsh gia èna sugkekrimèno jèma. Se autèc tic peript seic, oi lèxeic oi proforikèc ekfr seic jewroôntai wc prìtupa. H anðqneush enallag c skhn n apoteleð mia idiaðtera shmantik prìklhsh afoô, pollèc forèc, den up rqei antikeimenik lôsh sto prìblhma autì. Dhlad, o orismìc mðac apotelesmatik c mh grammik c prìsbashc se plhroforðec bðnteo eðnai arket asaf c. Genik, diaforetikoð njrwpoi mporoôn na qrhsimopoi soun diaforetik krit ria gia ton kajorismì twn orðwn twn skhn n. H kat stash gðnetai akìma duskolìterh kaj c qrhsimopoioôntai diaforetikoð kanìnec prokeimènou na kajoristoôn oi skhnèc gia ta thleoptik deltða eid sewn, tic thleoptikèc suzht seic, ta ntokimantèr tic tainðec. Sth didaktorik aut diatrib melet ntai ta proanaferjènta probl mata kai proteðnontai kainotìmec mejìdoi gia thn apotelesmatik antimet pish touc. Eidikìtera, parousi zetai mia prwtìtuph teqnik anagn rishc pros pou h opoða qrhsimopoieð dunamik ekpaðdeush me stìqo na epimerðsei th diadikasða anagn rishc se èna sônolo aplousteumènwn problhm twn taxinìmhshc. EpÐshc, perigr fetai mia kainotìmoc teqnik epibebaðwshc tautìthtac pros pou, h opoða efarmìzei èna sq ma stajmismènhc tmhmatik c diakritik c an lushc ste na periorðsei ta probl mata pou dhmiourgoôntai lìgw mh eparkoôc arijmoô deigm twn ekpaðdeushc. Epiplèon, proteðnetai mia prwtìtuph teqnik taxinìmhshc ekfr sewn pros pou h opoða par gei uyhl c poiìthtac qarakthristik kai epilègei touc pio axiìpistouc taxinomhtèc prokeimènou na prokôyei h apìfash taxinìmhshc. Tèloc, proteðnetai ènac nèoc algìrijmoc anðqneu-

5 shc enallag c skhn n se bðnteo, o opoðoc par gei beltiwmèna idioakoustik plaðsia kai sundu zei optikèc kai akoustikèc endeðxeic enallag c skhn n. Pio sugkekrimèna, sto kef laio 2 proteðnetai kai axiologeðtai ènac nèoc algìrijmoc anagn rishc pros pou pou qrhsimopoieð th mèjodo dunamik c ekpaðdeushc se èna sq ma polustadiak c omadopoðhshc. To prìblhma pou prospajoôme na lôsoume qrhsimopoi ntac ton algìrijmo autì eðnai autì pou parousi zetai ìtan leitourgoôme se meg lec b seic pros pwn, dhlad, ìtan o arijmìc atìmwn pou perièqontai se mða b sh eðnai meg loc. Autìc o algìrijmoc qrhsimopoieð th diakritik an lush (discriminant analysis) gia probol twn kl sewn pros pou kai ènan algìrijmo omadopoðhshc gia diamerismì twn proballìmenwn dedomènwn pros pou, sqhmatðzontac ètsi èna sônolo diakritik n om dwn. 'Epeita, mèsw miac epanalhptik c diadikasðac dhmiourgoôntai uposônola ta opoða perilamb noun tic pio qr simec om dec. O plhj rijmoc tou k je uposunìlou orðzetai qrhsimopoi ntac èna mètro pou basðzetai sthn entropða. H kalôterh antistoiqða tou upì taxinìmhsh pros pou epitugq netai ìtan diathreðtai mìno mða kl sh pros pou. H sugkekrimènh mèjodoc èqei elegqjeð peiramatik stic b seic dedomènwn/pros pwn ORL, XM2VTS, kai FERET, en qrhsimopoi jhke kai h b sh dedomènwn UMIST gia ekpaðdeush tou proteinìmenou algorðjmou. Ta peiramatik apotelèsmata upodeiknôoun ìti to proteinìmeno plaðsio antimetwpðzei apotelesmatik c to prìblhma thc anagn rishc pros pou. Sto kef laio 3 proteðnetai kai axiologeðtai mia prwtìtuph mèjodoc pou mporeð na qrhsimopoihjeð gia enðsqush thc apìdoshc twn mejìdwn epibebaðwshc tautìthtac pros pou pou efarmìzoun to krit rio Fisher. O algìrijmoc efarmìzetai sta dedomèna omoiìthtac sf lmatoc antistoiqðac kai dðnei genik lôsh sto prìblhma DeÐgmatoc MikroÔ Megèjouc [Small Sample Size (SSS)], sômfwna me to opoðo h sugkèntrwsh mh eparkoôc arijmoô deigm twn ekpaðdeushc èqei wc apotèlesma thn anakrib ektðmhsh tou uperepipèdou grammikoô diaqwrismoô metaxô twn kl sewn. Piì sugkekrimèna, to prìblhma autì parousi zetai ìtan o arijmìc twn deigm twn gia k je kl sh eðnai mikrìteroc thc di stashc twn deigm twn. Thn proteinìmenh mèjodo sunistoôn dôo anex rthta metaxô touc st dia. Arqik qrhsimopoieðtai èna sônolo stajmismènwn tmhmatik n diakritik n uperepipèdwn me stìqo megalôterh akrðbeia sthn apìfash diaqwrismoô se sqèsh me thn apìfash pou prokôptei apì thn paradosiak mejodologða Grammik c Diakritik c An lushc [Linear Discriminant Analysis (LDA)]. H anamenìmenh ikanìthta taxinìmhshc thc sugkekrimènhc teqnik c exet zetai mèsw miac seir c prosomoi sewn. Sth deôterh f sh orðzontai oi kat llhloi, kai eidikoð gia k je prìswpo, sunduasmoð bajmologi n omoiìthtac kai efarmìzetai mia diadikasða apaloif c twn akraðwn parathr sewn pou enisqôei akìmh perissìtero thn ikanìthta

6 KEF ALAIO 1. EISAGWG H epibebaðwshc pros pou. H proteinìmenh mèjodoc èqei axiologhjeð stic b seic dedomènwn pros pwn M2VTS kai XM2VTS. Ta peiramatik apotelèsmata deðqnoun ìti to proteinìmeno plaðsio antimetwpðzei apotelesmatik c to prìblhma thc epibebaðwshc tautìthtac pros pou. Sto kef laio 4 proteðnetai kai axiologeðtai mia nèa mèjodoc taxinìmhshc twn ekfr sewn tou pros pou. H mèjodoc aut èqei wc stìqo na lôsei to prìblhma taxinìmhshc qwrðc na epiqeirhjeð na gðnei tautìqronoc diaqwrismìc ìlwn twn kl - sewn, kaj c autì den eðnai p nta efiktì. H diadikasða taxinìmhshc aposuntðjetai sth lôsh pollapl n problhm twn taxinìmhshc dôo kl sewn, epilog gia thn opoða parèqetai majhmatik epiqeirhmatologða, kai apì aut th diadikasða ex gontai monadik sônola qarakthristik n gia k je prìblhma taxinìmhshc. Pio sugkekrimèna, gia k je prìblhma dôo kl sewn, pragmatopoieðtai mia epanalhptik diergasða epilog c qarakthristik n, h opoða basðzetai se èna mètro diaqwrisimìthtac kl sewn, prokeimènou na dhmiourghjoôn ta dianôsmata <<shmantikìterwn>> qarakthristik n, ìpou k je di nusma apoteleðtai apì èna epilegmèno uposônolo qarakthristik n. AkoloÔjwc, efarmìzetai diakritik an lush dôo kl sewn se aut ta dianôsmata prokeimènou na paraqjoôn ta <<shmantikìtera>> diakritik uperepðpeda, ta opoða qrhsimopoioôntai gia thn ekpaðdeush twn antðstoiqwn taxinomht n dôo kl sewn. Prokeimènou na enswmatwjoôn katall lwc ta apotelèsmata taxinìmhshc dôo kl sewn ste na prokôyei h apìfash taxinìmhshc ekfr sewn pros pou, èqei anaptuqjeð èna upologistik c apotelesmatikì sq ma taxinìmhshc, to opoðo sugkentr nei k poia qr sima qarakthristik. Se k je b ma autoô tou sq matoc, entopðzetai kai qrhsimopoieðtai o pio axiìpistoc taxinomht c kai kat autìn ton trìpo prokôptei mia pio akrib c telik apìfash taxinìmhshc. H b sh dedomènwn JAFFE qrhsimopoieðtai sthn axiolìghsh thc apìdoshc thc mejìdou mac. Ta apotelèsmata upodeiknôoun pwc h proteinìmenh mejodologða, h opoða epilègei ta pio qr sima qarakthristik kai touc pio axiìpistouc taxinomhtèc, antimetwpðzei apotelesmatik c to prìblhma taxinìmhshc twn ekfr sewn pros pou. Sto kef laio 5 proteðnetai kai axiologeðtai peiramatik ènac nèoc optikoakoustikìc algìrijmoc anðqneushc enallag c skhn n se bðnteo. To prìblhma pou lônei o algìrijmoc autìc eðnai o tautìqronoc entopismìc shmantik c allag c perieqomènou tìso sto optikì ìso kai sto akoustikì kan li. DhmiourgeÐtai èna beltiwmèno (enhanced) sônolo idio-akoustik n plaisðwn to opoðo antistoiqeð se ènan upoq ro akoustikoô s matoc ìpou entopðzontai eôkola oi allagèc akoustikoô upìbajrou. Parousi zetai mia an lush h opoða tekmhri nei giatð autìc o upoq roc dieukolônei thn anðqneush thc enallag c skhn n. Wc ek toôtou, anaptôssetai mia nèa diadi-

7 kasða me stìqo thn anðqneush upoyhfðwn shmeðwn enallag c akoustik n skhn n sto sugkekrimèno upoq ro. Epiplèon, qrhsimopoioôntai optikèc plhroforðec me stìqo thn eujugr mmish twn endeðxewn enallag c akoustik n skhn n me tic geitonikèc enallagèc pl nwn tou bðnteo kai, kat sunèpeia, th meðwsh tou posostoô lanjasmènhc akoustik c-mìno anðqneushc enallag c skhn n. Epiplèon, entopðzontai ta efè monìtonhc metabol c fwteinìthtac (fade) tou bðnteo, ta opoða qrhsimopoioôntai anex rthta gia ton entopismì enallag c skhn n. To posostì lanjasmènhc anðqneushc mei netai akìmh perissìtero me thn exagwg poikðlwn akoustik n qarakthristik n, me stìqo thn pijan epikôrwsh twn endeðxewn enallag c skhn n. H mejodologða anðqneushc èqei axiologhjeð se bðnteo apì deltða eid sewn sto plaðsio thc seir c dokimastik n bðnteo TRECVID2003. Ta peiramatik apotelèsmata upodeiknôoun ìti h proteinìmenh mèjodoc antimetwpðzei apotelesmatik c to prìblhma thc anðqneushc enallag c skhn n.

8 KEF ALAIO 1. EISAGWG H

Kef laio 2 Anagn rish Tautìthtac Pros pou 2.1 Eisagwg H anagn rish pros pou [Face Recognition (FR)] apoteleð èna energì pedðo èreunac sto opoðo èqei dojeð meg lh prosoq ta teleutaða qrìnia. To sôsthma anagn rishc pros pou prospajeð sun jwc na exakrib sei thn tautìthta tou upì anagn rish pros pou. H diadikasða pou akoloujeðtai eðnai o upologismìc kai h taxinìmhsh ìlwn twn bajmologi n omoiìthtac an mesa sto upì taxinìmhsh prìswpo kai sta prìswpa pou eðnai apojhkeumèna sth b sh dedomènwn tou sust matoc ta opoða kai apoteloôn to sônolo ekpaðdeushc. Sun jwc, h apìdosh mejìdwn FR pou apoteloôn shmeða anafor c mei netai ragdaða ìtan oi b seic dedomènwn eðnai meg lec, anaforik me ton arijmì pros pwn pou perièqoun [1, 2]. Sugkekrimèna, h anapar stash twn qarakthristik n pros pou h opoða pragmatopoieðtai mèsw mejìdwn pou efarmìzoun grammik krit ria, ta opoða kanonik apaitoôn oi eikìnec pros pou na akoloujoôn mia kurt katanom, den mporeð na genikeôsei ìlec tic diakum nseic pou parousi - zontai. Autì sumbaðnei lìgw twn meg lwn diafor n pou parathroôntai sthn optik gwnða, sto fwtismì, kai stic ekfr seic pros pou, ìtan ta sônola dedomènwn eðnai meg la. 'Otan qrhsimopoioôntai oi mh grammikèc mèjodoi anapar stashc pros pou, parousi zontai suqn probl mata, ìpwc h uperprosarmog, h upologistik poluplokìthta kai oi duskolðec sth beltistopoðhsh twn sqetik n paramètrwn [1]. Epiplèon, h apìdosh thc anagn rishc pros pou mei netai ìtan parousi zetai èlleiyh arket 9

10 KEF ALAIO 2. ANAGN WRISH TAUT OTHTAS PROS WPOU meg lou arijmoô deigm twn ekpaðdeushc/ekm jhshc gia k je prìswpo sth b sh dedomènwn ìpwc kai ìtan oi endotaxikèc diakum nseic den mporoôn na montelopoihjoôn kat llhla. Pio sugkekrimèna, oi grammikèc mèjodoi, ìpwc h Grammik Diakritik An lush [Linear Discriminant Analysis (LDA)], antimetwpðzoun suqn to prìblhma deðgmatoc mikroô megèjouc [small sample size (SSS)], ìpou h di stash twn deigm twn eðnai megalôterh apì ton arijmì twn diajèsimwn deigm twn ekpaðdeushc [3]. 2.1.1 Episkìphsh teqnik n Prìsfata, prot jhkan di forec mèjodoi gia ton periorismì twn sunepei n pou prokôptoun apì touc dôo proanaferìmenouc tôpouc problhm twn kai pou aforoôn thn apìdosh twn mejìdwn anagn rishc. H arq fidiaðrei kai basðleuefl, efarmìsthke eurèwc. Me th sugkekrimènh arq h b sh dedomènwn diasp zetai se mikrìtera sônola gia thn tmhmatik ekm jhsh thc polôplokhc katanom c apì èna meðgma topik n grammik n montèlwn. Sto [1], efarmìzetai èna krit rio diaqwristikìthtac gia th diamèrish tou sunìlou ekpaðdeushc apì mia meg lh b sh dedomènwn se èna sônolo mikrìterwn Om dwn Mègisthc Diaqwristikìthtac [Maximal Separability Clusters (MSCs)] mèsw miac teqnik c parìmoiac me thn LDA. Basizìmenoi stic sugkekrimènec om dec, efarmìzetai èna ierarqikì plaðsio taxinìmhshc, to opoðo apoteleðtai apì ta dôo epðpeda twn pio geitonik n taxinomht n kai entopðzetai ètsi h pio kontin antistoiqða. H ergasða [4] epikentr netai sthn ierarqik diamèrish twn qarakthristik n efarmìzontac thn Ierarqik Diakritik An lush [Hierarchical Discriminant Analysis (HDA)]. To dèntro thc mejìdou kat tmhshc tou q rou prokôptei qrhsimopoi ntac ta Pio Ekfrastik Qarakthristik [Most Expressive Features (MEF)] efarmìzontac thn An lush KurÐwn Sunistws n [Principal Component Analysis (PCA)] kai ta Pio Diakritik Qarakthristik [Most Discriminant Features (MDF)], efarmìzontac thn LDA se k je epðpedo dèntrou. Autì sumbaðnei gia thn apofug twn periorism n pou sundèontai me genik qarakthristik, ex gontac èna kalôtera prosarmosmèno sônolo qarakthristik n gia k je èna apì ta upodiairoômena sônola twn deigm twn ekpaðdeushc. Genik, ta ierarqik dèntra èqoun qrhsimopoihjeð ektetamèna gia skopoôc anagn rishc protôpwn. H LDA apoteleð èna shmantikì statistikì ergaleðo to opoðo èqei apodeiqteð apotelesmatikì gia probl mata anagn rishc epibebaðwshc tautìthtac pros pou [5, 6]. Kat paradosiakì trìpo, gia na beltiwjoôn oi mejìdoi pou basðzontai sthn LDA kai na dwjoôn lôseic sto prìblhma SSS, efarmìzetai h LDA se ènan mikrìterwn diast sewn upoq ro PCA, prokeimènou na aporrifjeð o mhdenikìc upoq roc

2.1. EISAGWG H 11 (dhl. o upoq roc pou orðzetai apì idiodianôsmata ta opoða antistoiqoôn se mhdenikèc idiotimèc) tou pðnaka endotaxik c (within-class) diaspor c tou sunìlou dedomènwn ekpaðdeushc [5]. Parìla aut, èqei apodeiqteð [7] ìti o aporrifjeðc autìc q roc perièqei shmantikèc plhroforðec diaqwrismoô kai sunep c èqoun anazhthjeð enallaktikèc lôseic. Sugkekrimèna, sto [8] parousi zetai ènac mesoc-lda algìrijmoc [direct-lda (DLDA)] pou aporrðptei ton mhdenikì q ro tou diataxikoô (between-class) pðnaka diaspor c, o opoðoc jewreðtai ìti den perièqei kamða shmantik plhroforða, kai ìqi ton mhdenikì q ro tou endotaxikoô pðnaka diaspor c. Pio prìsfata, se mia prosp jeia epðlushc tou probl matoc SSS, parousi sthke sto [9] h mèjodoc thc omalopoihmènhc LDA [Regularized LDA (RLDA)], h opoða qrhsimopoieð èna omalopoihmèno krit rio diaqwristikìthtac Fisher. O stìqoc thc omalopoðhshc eðnai h meðwsh thc uyhl c diakômanshc pou sqetðzetai me tic ektim seic twn idiotim n tou endotaxikoô pðnaka diaspor c eic b roc endeqìmenhc aôxhshc thc pìlwshc merolhyðac (bias) ìson afor thn taxinìmhsh. H qr sh statik n dom n ekpaðdeushc, ìpou ta dedomèna eisìdou den emplèkontai ston kajorismì twn paramètrwn tou sust matoc, eðnai ektetamènh ston sqediasmì twn susthm twn taxinìmhshc protôpwn. Parìla aut, èqei apodeiqteð ìti h apìdosh thc taxinìmhshc mporeð na beltiwjeð efarmìzontac dunamikèc domèc ekpaðdeushc. 'Etsi loipìn, sto [10] parousi sthke o algìrijmoc anagn rishc pros pou Dunamik Mhqan Eidik n (AlgorÐjmwn) [Dynamic Committee Machine (DCM)], apoteloômeno apì pènte algìrijmouc taxinìmhshc protôpwn pou eðqan atomik parousi sei polô kal apotelèsmata. H proteinìmenh dunamik dom apaiteð thn mesh emplok twn dedomènwn eisìdou ston mhqanismì sunduasmoô gia na prosarmìsei to b roc tou k je eidikoô (algìrijmou). 'Ena dðktuo qrhsimopoieðtai gia na exakrib sei thn kat - stash kat thn opoða l fjhke h eikìna eisìdou kai na kajorðsei sugkekrimèna b rh se k je eidikì. Peiramatik apotelèsmata deðqnoun ìti h efarmog thc sugkekrimènhc dunamik c dom c dðnei uyhlìtera posost anagn rishc apì thn efarmog miac statik c dom c, ìpou ta b rh gia k je eidikì eðnai kajorismèna. Sto [11], ex getai o upoq roc LDA tou nìmimou katìqou, gia na dhmiourghjeð èna sôsthma exatomikeumènhc epibebaðwshc tautìthtac pros pou (taxinìmhsh 2 kl sewn), ìpou h tautìthta tou katìqou eðnai h pragmatik. To sônolo ekpaðdeushc diamerðzetai se ènan arijmì om dwn kai anagnwrðzetai h om da pou perièqei ekeðna ta dedomèna pros pou ta opoða tairi zoun perissìtero ston nìmimo k toqo. To sôsthma kataqwreð tic eikìnec ekpaðdeushc tou katìqou sth sugkekrimènh om da. Autì to sônolo nèwn dedomènwn efarmìzetai gia na kajoristeð o upoq roc LDA, o opoðoc qrhsimopoieðtai gia ton upologismì twn katwflðwn epibebaðwshc kai twn bajmologi n antistoðqishc, ìtan

12 KEF ALAIO 2. ANAGN WRISH TAUT OTHTAS PROS WPOU èna upì taxinìmhsh prìswpo isqurðzetai ìti eðnai o nìmimoc k toqoc. Oi suggrafeðc deðqnoun ìti h apìdosh thc epibebaðwshc belti netai me th qr sh tou upoq rou proswpopoihmènhc/exeidikeumènhc LDA tou nìmimou katìqou, antð thc qr shc tou q rou thc LDA pou dhmiourgeðtai mèsw thc epexergasðac olìklhrou tou sunìlou ekpaðdeushc. 2.1.2 MejodologÐa Dunamik c EkpaÐdeushc gia Polustadiak OmadopoÐhsh Sto kef laio autì proteðnetai mia prwtìtuph mèjodoc pou efarmìzei Dunamik EkpaÐdeush, qrhsimopoi ntac diakritik an lush, se mia diadikasða Polustadiak c OmadopoÐhshc [Dynamic Training for Multistage Clustering (DTMC)]. Gia lìgouc suntomografðac, o sugkekrimènoc algìrijmoc ja anafèretai wc DTMC sto upìloipo thc enìthtac. H sugkekrimènh mejodologða den periorðzetai sthn anagn rish pros pou, all mporeð na antimetwpðsei kai opoiod pote prìblhma antistoiqeð sthn Ðdia tupologða. Se autì to shmeðo, ja prèpei na prosdiorðsoume touc dôo ìrouc pou qrhsimopoioôntai suqn sthn ergasða: h fikl shfl anafèretai se sônolo twn eikìnwn tou Ðdiou atìmou, en h fiom dafl anafèretai se sônolo twn kl sewn. Arqik, pragmatopoieðtai h exagwg twn qarakthristik n pros pou mèsw tou algìrijmou PoluepÐpedhc Disdi stathc Kumatidiak c (wavelet) AposÔnjeshc [2-D Multilevel Wavelet Decomposition (MWD2)] [12, 13], pou odhgeð se meðwsh diast sewn (mèsw epilog c qarakthristik n qamhl c an lushc), kai èqei brejeð na eðnai kat llhloc se jèmata taxinìmhshc [6, 14, 15]. Sth sunèqeia, ta dianôsmata twn qarakthristik n ekpaðdeushc/ekm jhshc kai aut tou upì taxinìmhsh pros pou prob llontai ston q ro twn MDF, o opoðoc dhmiourgeðtai efarmìzontac th mèjodo RLDA tou [9]. AkoloÔjwc, o algìrijmoc k-mèswn (k-means) qrhsimopoieðtai gia th diamèrish twn dedomènwn ekpaðdeushc, sto nèo autì q ro, se èna sônolo diakritik n/diaqwristik n om dwn. H apìstash tou upì taxinìmhsh pros pou apì ta kèntra b rouc twn om dwn qrhsimopoieðtai gia th sullog enìc uposunìlou twn om dwn ekeðnwn pou brðskontai pio kont sto upì taxinìmhsh prìswpo. O plhj rijmoc autoô tou uposunìlou orðzetai me èna mètro pou basðzetai sthn entropða kai upologðzetai qrhsimopoi ntac to istìgramma suqnot twn. Sth sunèqeia, ènac nèoc q roc MDF dhmiourgeðtai apì autì to uposônolo om dwn. Oi diast seic tou eðnai tètoiec, ste na mei nontai ta probl mata taxinìmhshc pou phg zoun apì pijanèc meg lec diakum nseic sto sônolo twn eikìnwn k je kl shc pros pou. Ta dedomèna ekpaðdeushc pou prob llontai se autìn ton nèo q ro omadopoioôntai xan kai epilègetai èna nèo uposônolo pou brð-

2.1. EISAGWG H 13 sketai pio kont sto upì taxinìmhsh prìswpo. H diadikasða aut pragmatopoieðtai epanalhptik ìsec forèc apaiteðtai, mèqri na epilegeð mða mìno om da pou na perièqei mða mìno kl sh pros pou. H tautìthta aut c thc kl shc pros pou orðzetai wc h kalôterh antistoiqða sthn tautìthta tou upì taxinìmhsh pros pou. 2.1.3 Sumbol kai dom tou kefalaðou H proteinìmenh mèjodoc eðnai upologistik apotelesmatik, sugkritik me tic teqnikèc tou fidiaðrei kai basðleuefl, ìpwc gia par deigma aut sto [1], ìpou par gontai pollapl apotelèsmata taxinìmhshc me thn efarmog thc diadikasðac thc diakritik c an lushc kai tou pio kontinoô taxinomht gia k je mia om da. H mèjodìc mac efarmìzei mða mìno diakritik an lush se k je epðpedo omadopoðhshc. 'Opwc ja faneð met, o arijmìc twn epipèdwn omadopoðhshc eðnai genik polô mikrìteroc apì ton arijmì twn om dwn, kaj c mìno èna mikrì uposônolo twn dedomènwn ekpaðdeushc diathreðtai se k je epðpedo. 'Ena meg lo upologistikì kìstoc sunodeôei touc algìrijmouc pou dhmiourgoôn ierarqik dèntra katetmhmènouc q rouc, ìpwc sthn perðptwsh efarmog c tou algìrijmou HDA sto [4]. Stìqoc autoô tou tôpou algìrijmwn eðnai na d soun mia kal diakritik lôsh gia k je mða apì tic kl seic pros pou xeqwrist, mèsw thc anagwgik c upodiaðreshc tou sunìlou twn deigm twn ekpaðdeushc se mikrìtera probl mata taxinìmhshc. Apì thn llh meri, o algìrijmìc mac to mìno pou prèpei na k nei se k je st dio omadopoðhshc eðnai na d sei mia diakritik lôsh gia ekeðnec tic kl seic pros pou pou brðskontai pio kont sto upì taxinìmhsh prìswpo. Ta dedomèna ekpaðdeushc pou antistoiqoôn stic upìloipec kl seic pros pwn aporrðptontai. H dom tou algorðjmou DTMC eðnai endeqomènwc pio euèlikth ìson afor sthn prosj kh nèwn pros pwn ekpaðdeushc. Sugkekrimèna, ìtan èna nèo prìswpo ekpaðdeushc prostðjetai sth b sh dedomènwn, tìte h mình allag pou apaiteðtai sth diadikasða DTMC eðnai na auxhjeð h di stash tou pr tou q rou MDF kat èna. Ta qarakthristik tou upì taxinìmhsh pros pou ja kajorðsoun poio sônolo om dwn ja diathrhjeð sto epðpedo omadopoðhshc pou akoloujeð. To sônolo autì mporeð na perièqei thn kl sh nèou pros pou ekpaðdeushc, all mporeð kai ìqi. AntÐjeta, h dom tou ierarqikoô dèntrou apaiteð, endeqomènwc, mia ek nèou pl rh m jhsh olìklhrou tou q rou ekpaðdeushc, kaj c o nèoc q roc MDF sto pr to epðpedo tou dèntrou mporeð na odhg sei se èna entel c diaforetikì apotèlesma di spashc. Oi q roi MDF, touc opoðouc qrhsimopoioôn oi domèc twn ierarqik n dèntrwn twn katetmhmènwn q rwn, prokôptoun sth f sh thc ekpaðdeushc kai den ephre zontai

14 KEF ALAIO 2. ANAGN WRISH TAUT OTHTAS PROS WPOU apì ta qarakthristik tou upì taxinìmhsh pros pou. AntÐjeta, oi q roi MDF pou dhmiourgoôntai se k je epðpedo omadopoðhshc tou algìrijmou DTMC eðnai pr gmati merolhptikoð se sqèsh me ta qarakthristik tou upì taxinìmhsh pros pou. Basismènoi sta sumper smata twn [10] kai [11] pou sunoyðzontai parap nw, ta apotelèsmata taxinìmhshc apì ton DTMC anamènetai na eðnai pio akrib, kaj c o algìrijmoc autìc efarmìzei mia dunamik dom taxinìmhshc h opoða qrhsimopoieð mia seir upoq rwn eidik n tou upì taxinìmhsh pros pou. H dom autoô tou kefalaðou èqei wc ex c: H Enìthta 2.2 perigr fei th mèjodo exagwg c qarakthristik n h opoða qrhsimopoieð ton algìrijmo MWD2, epanexet zei th mèjodo RLDA pou qrhsimopoieðtai gia thn exagwg twn q rwn MDF prin apì k je diadikasða omadopoðhshc kai parousi zei ton algìrijmo k-mèswn pou qrhsimopoieðtai sth diamèrish twn dedomènwn ekpaðdeushc, kaj c kai to mètro pou basðzetai sthn entropða kai pou qrhsimopoieðtai gia na orðsei ton arijmì twn om dwn pou diathroôntai. H Enìthta 2.3 perigr fei thn oloklhrwmènh mejodologða thc anagn rishc pros pou mèsw tou DTMC h opoða proteðnetai sthn paroôsa ergasða. Sthn Enìthta 2.4 parousi zontai ta peiramatik apotelèsmata, ìpou dokim zetai h mejodologða tou DTMC qrhsimopoi ntac tic kal gnwstèc b seic dedomènwn UMIST [16], ORL [17], kai XM2VTS [18] prokeimènou na ektimhjoôn oi ikanìthtec anagn rishc se tupik sônola dedomènwn Epiprìsjeta, h apìdosh tou DTMC tðjetai se sôgkrish me di forouc algìrijmouc FR pou èqoun protajeð prìsfata apì thn ereunhtik koinìthta. 2.2 Epilog qarakthristik n kai h dom tou DTMC O kat llhloc metasqhmatismìc kumatidðwn mporeð na odhg sei se polô kal anapar stash eikìnwn, antimetwpðzontac apotelesmatik tic metabolèc fwteinìthtac kaj c kai th l yh qr simwn qarakthristik n pros pou, diathr ntac thn upologistik poluplokìthta qamhl [14]. H dom tou MWD2 perigr fetai leptomer c sta [12, 13]. O algìrijmoc autìc efarmìzetai sto st dio exagwg c qarakthristik n thc mejìdou pou proteðnetai kai aposunjètei tic eikìnec se pollaplèc analôseic. Mia seir fðltrwn an lushc, h opoða sun jwc apoteleðtai apì èna qamhloperatì fðltro, Lo D, kai èna uyiperatì fðltro, Hi D, qrhsimopoieðtai gia na aposunjèsei to s ma sth sunist sa qamhl c suqnìthtac tou kai stic sunist sec uyhl c suqnìthtac tou se treic diaforetikoôc prosanatolismoôc [19]. To mègisto epðpedo aposônjeshc J d tou s matoc sqetðzetai me to epðpedo Ôyisthc an lushc (resolution) tou s matoc J apì thn exðswsh J d = J j, ìpou j

2.2. EPILOG H QARAKTHRISTIK WN KAI H DOM H TOU DTMC 15 eðnai to trèqon epðpedo an lushc tou s matoc. Sthn paroôsa ergasða, to krit rio pou qrhsimopoieðtai gia na orðsei to J d apaiteð ènac toul qiston suntelest c tou suneliktikoô apotelèsmatoc na upologðzetai kat llhla, lamb nontac upìyh ìti h suqnìthta deigmatolhyðac tou s matoc met th sunèlixh mei netai kat ènan par gonta thc t xewc 2 se k je klðmaka. Sunep c, prèpei na isqôoun ta akìlouja: 2 J d (max (N Hi D,N Lo D ) 1) < min (Nv,N h ), ìpou N v kai N h eðnai oi k jetec kai orizìntiec diast seic tou disdi statou s matoc f, kai N Hi D kai N Lo D eðnai o arijmìc twn stoiqeðwn twn fðltrwn Hi D kai Lo D, antðstoiqa. To J d upologðzetai wc ( log 2 J d = min(n v,n h ) max(n Hi D,N Lo D) 1 log 2 (2) ). (2.1) ProhgoÔmenec èreunec èdeixan ìti oi sunist sec qamhl c an lushc thc aposônjeshc kumatidðwn eðnai ekeðnec pou prosfèroun thn pio qr simh plhroforða ìson afor thn taxinìmhsh pros pou [6]. Sto [20] to sumpèrasma tan ìti oi ekfr seic tou pros pou kai oi mikrèc apokrôyeic pros pou ephre zoun topik tic diaforèc ent sewc twn eikìnwn, kai sômfwna me thn parousðash pou basðzetai sth suqnìthta sumperaðnetai ìti ephre zetai mìno to uyhl c suqnìthtac f sma. ParomoÐwc, sto [21] èqei parathrhjeð ìti h epðdrash twn diaforetik n ekfr sewn pros pou mporeð na meiwjeð afair ntac tic sunist sec uyhl c suqnìthtac. Sunep c, oi suntelestèc kumatidðwn pou antistoiqoôn sth z nh qamhlìterhc suqnìthtac thc klðmakac J d ( antðstoiqa tou epipèdou an lushc J =0) epilègontai wc to sônolo twn qarakthristik n pou ja epexergasteð o algìrijmoc DTMC. Majhmatik, ac orðsoume thn aposônjesh tou s matoc f stouc suntelestèc kumatidðwn pou antistoiqoôn sto epðpedo an lushc J =0 (dhl. stouc suntelestèc kumatidðwn prosèggishc tou f) wc f A 0. To spline biorthogonal wavelet bior3.5 [13] qrhsimopoieðtai gia na prosdiorðsei touc suntelestèc twn fðltrwn an lushc Lo D kai Hi D. 2.2.1 EÔresh twn MDF q rwn mèsw tou RLDA H mèjodoc RLDA qrhsimopoieð to akìloujo omalopoihmèno krit rio tou diaqwrist Fisher, to opoðo eðnai idiaðtera apotelesmatikì ìson afor sthn antimet pish tou probl matoc SSS en sugkrðsh me to aujentikì [9]: W o = arg max W W T S b W R (W T S b W)+(W T S w W), (2.2)

16 KEF ALAIO 2. ANAGN WRISH TAUT OTHTAS PROS WPOU ìpou S b eðnai o diataxikìc pðnakac diaspor c, S w eðnai o endotaxikìc pðnakac diaspor c, kai 0 R 1 eðnai h par metroc pou elègqei thn isqô thc omalopoðhshc. O algìrijmoc RLDA perigr fetai leptomer c sto [9]. O stìqoc thc omalopoðhshc eðnai h meðwsh thc uyhl c diakômanshc stic ektim seic idiotim n tou S w, eic b roc endeqìmenhc aôxhshc thc pìlwshc ston upologismì tou W. O kajorismìc thc bèltisthc tim c tou R eðnai upologistik apaithtikìc, kaj c basðzetai se exantlhtik anaz thsh [9]. Sthn paroôsa ergasða, brðsketai mia prosèggish thc bèltisthc aut c tim c se k je epðpedo omadopoðhshc qrhsimopoi ntac ta dedomèna apì th b sh dedomènwn UMIST. 2.2.2 H mèjodoc omadopoðhshc k-mèswn Se èna sônolo N dianusm twn dedomènwn, pou prokôptei apì to y n,n=1,...,n,sto d-di stato q ro, o algìrijmoc k-mèswn qrhsimopoieðtai gia na prosdiorðsei èna sônolo K dianusm twn sto R d, pou apokaloôntai kèntra b rouc (centroids) twn om dwn, gia na elaqistopoihjeð to sônolo twn apost sewn dianôsmatoc-mèqri-kèntro b rouc pou ajroðzetai gia ìlec tic K om dec [22, 23]. H antikeimenik sun rthsh (objective function) tou algìrijmou k-mèswn pou qrhsimopoieð h paroôsa ergasða k nei efarmog tou tetrag nou thc EukleÐdeiac apìstashc kai parousi zetai sto [22]. AfoÔ brejoôn ta kèntra b rouc twn om dwn, èna di nusma x mporeð na oristeð/anatejeð sth om da me thn el qisth apìstash dianôsmatoc-mèqri-kèntro b rouc thc om dac, metaxô twn K apost sewn pou upologðzontai. To mètro thc EukleÐdeiac apìstashc qrhsimopoieðtai gia na upologðsei autèc tic apost seic: D i (x, μ i )= x μ i,i=1,...,k. (2.3) 2.2.3 MeÐwsh tou plhj rijmou tou sunìlou ekpaðdeushc me thn efarmog mètrou pou basðzetai sthn entropða Ac jewr soume èna sônolo K om dwn diamerðsewn ston q ro dedomènwn T. perib llousa perioq Voronoi thc i- c om dac dhl netai wc V i. Jewrhtik, h ek twn protèrwn (a priori) pijanìthta gia k je om da na apoteleð thn kalôterh antistoiqða gia èna opoiod pote deigmatikì di nusma x tou q rou qarakthristik n upologðzetai wc ex c, an eðnai gnwst h sun rthsh puknìthtac pijanìthtac (probability density function) p (x): P i = P (x V i )= p (x) dx. (2.4) V i H