Black or White Video. Lecture 3: Face Detection. Face Detection. Why is Face Detection Difficult? Automated Face Detection Why is it Difficult?

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Jacob Chandler
5 years ago
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Back or Whte Veo ecture : Face Detecto Reag: Egeaces oe paper FP pgs 55-5

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1 Back or Whte Veo ecture : Face Detecto Reag: Egeaces oe paper FP pgs 55-5 Haouts: Course Descrpto P Assge Face Detecto Face ocazato egmetato Face rackg Faca eatures ocazato Faca eatures trackg orphg wwwyoutubecom/watch?vzi9oyrwq I I ook at your ace I mmeatey recogze that I have see t beore Yet there s o mache whch, wth that spee, ca take a pcture o a ace a say eve that t s a ma; a much ess that t s the same ma that you showe t beore uess t s eacty the same pcture I the ace s chage; I am coser to the ace; I am urther rom the ace; the ght chages I recogze t ayway ow, ths tte computer I carry my hea s easy abe to o that he computers that we bu are ot abe to o that Why s Face Detecto Dcut? evere umato chage Rchar P Feyma, Dec 9, 959 here's Pety o Room at the Bottom A Ivtato to Eter a ew Fe o Physcs Automate Face Detecto Why s t Dcut? Varyg vewpot, umato, etc Face Detecto

2 Coceta appearace o aces rock? Coceta appearace o ace proe rock? Face Detecto earest eghbor Caser Eucea stace: y ( ) y y c yc c ear oes Gve a put mage y (aso cae a probe), the casser w assg to y the abe assocate wth the cosest mage the trag set o, t happes to be cosest to aother ace t w be assge (ace), otherwse t w be assge (oace)

3 R k A mage s a pot mesoa space Images R k k I R pe pe k pe Image Represetato k k I ) ( k k by Ae O Vasescu pe vaue as represetg pe Image Represetato k O Bass atr, B vector o coecets, c by Ae O Vasescu Bc k k I ) ( k Represetato F a ew bass matr that resuts a compact represetato oy Eampe - Represetato Heurstc Coser a set o mages o peope uer the same vewpot a ghtg Each mage s mae up o pes a pe has the same vaue as pe or a mages pe pe pe a st by Ae O Vasescu oy Eampe - Represetato Heurstc Coser a set o mages o peope uer the same vewpot a ghtg Each mage s mae up o pes a pe has the same vaue as pe or a mages pe pe pe a st by Ae O Vasescu Bass atr, B

4 oy Eampe - Represetato Heurstc Coser a set o mages o peope uer the same vewpot a ghtg Each mage s mae up o pes a pe has the same vaue as pe or a mages pe ew bass by Ae O Vasescu pe pe st a Bc ew Bass atr, B pe oy Eampe-Recogto ove or a store the coecet matr C: c D, ata matr C, coecet matr C B D Gve a ew mage, ew : pe 5 5 ew ew ew c B ew pe ew et, compare c ew a reuce mesoaty represetato o ew agast a coecet vectors c c c Oe possbe casser: earest-eghbor casser Prcpa Compoet Aayss: Egeaces Empoys seco orer statstcs to compute a prcpe way a ew bass matr Varabes Respose Varabes are recty measurabe, they measure the outcome o a stuy Pes are respose varabes that are recty measurabe rom a mage Epaatory Varabes, Factors epa or cause chages the respose varabe Pe vaues chage wth scee geometry, umato ocato, camera ocato whch are kow as the epaatory varabes Respose vs Epaatory Varabes Pes (respose varabes, recty measurabe rom ata) chage wth chages vew a umato, the epaatory varabes (ot recty measurabe but o actua terest) he Prcpe Beh Prcpa Compoet Aayss Aso cae: - Hotteg rasorm or the - Karhue-oeve etho F a orthogoa coorate system such that ata s appromate best a the correato betwee eret as s mmze IJoe; Prcpe Compoet Aayss; 986 RCGozaas, PAWtz; Dgta Image Processg; 987 KKarhue; Uber eare ethoe er Wahrschechkets Rechug; 946 oeve; Probabty heory; 955

5 PCA: heory PCA Dee a ew org as the mea o the ata set F the recto o mamum varace the sampes (e ) a ag t wth the rst as (y ), Cotue ths process wth orthogoa rectos o ecreasg varace, agg each wth the et as hus, we have a rotato whch mmzes the covarace y e e y PCA-Dmesoaty Reucto Coser a set o mages, & each mage s mae up o pes a pe has the same vaue as pe or a mages [ ] st a PCA chooses as the recto o hghest varabty o the ata, mamum scatter pe st as pe as pe ata matr, D c Each mage coecets D UV Bc c c s ow represete by a vector o a reuce mesoaty space (sv o D) B mmze the oowg ucto set B U E B B such that B B Ietty he Covarace atr Dee the covarace (scatter) matr o the put sampes: ( µ)( (where µ s the sampe mea) µ µ µ) ( D )( D ) where [ µ µ ] µ µ µ µ PCA: ome Propertes o the Covarace/catter atr he matr s symmetrc he agoa cotas the varace o each parameter (e eemet, s the varace the th recto) Each eemet,j s the co-varace betwee the two rectos a j, represets the eve o correato (e a vaue o zero cates that the two mesos are ucorreate) catter o matr: VD o a atr ( D ) UΣV by sv o ( D- ) ( D )( D ) UΣ U (sv o ) ( D )( D ) set B U set B U ook or: -B uch that: PCA: Goa Revste [c c ] B [ ] correato s mmze Cov(C) s agoa ote that Cov(C) ca be epresse va Cov(D) a B : CC B ( D )( D ) B B B

6 eectg the Optma B Data Reucto: heory How o we such B? ( D µ )( D µ ) b λ b B ΛB B opt cotas the egevectors o the covarace o D Each egevaue represets the the tota varace ts meso hrowg away the east sgcat egevectors B opt meas throwg away the east sgcat varace ormato Bopt [b b] Coser the set o mages PCA or Recogto [ ] a st PCA chooses as the recto o hghest varabty o the ata Data a Egeaces Data s compose o 8 aces photographe uer same ghtg a vewg cotos Gve a ew mage,, compute the vector o coecets assocate wth the ew bass, B ew c ew pe st as pe as c B B B ew ew c ew et, compare a reuce mesoaty represetato o ew agast a coecet vectors c Oe possbe casser: earest-eghbor casser Each mage beow s a coum vector the bass matr B pe by Ae O Vasescu by Ae O Vasescu Egemages Prcpa compoets (egevectors) o mage esembe pe k 55 ear Represetato: c c c9 55 pe pe k 55 c c 55 c pe c8 55 pe pe 55 Uc Uc Rug um: term terms 9 terms 8 terms Egevectors are typcay compute usg the guar Vaue Decomposto (VD) agorthm

he Covarace atr PIE Database (Wezma) Dee the covarace (scatter) matr o the put sampes: ( µ)( µ) (where µ s the sampe mea) EgeImages-Bass Vectors PCA Casser Dstace to Face ubspace: Each mage beow s a

7 he Covarace atr PIE Database (Wezma) Dee the covarace (scatter) matr o the put sampes: ( µ)( µ) (where µ s the sampe mea) EgeImages-Bass Vectors PCA Casser Dstace to Face ubspace: Each mage beow s a coum vector the bass matr B PCA ecoes ecoes the varabty across mages wthout stgushg betwee varabty peope, vewpots a umato by Ae O Vasescu ( y) y U U y kehoo rato (R) test to cassy a probe y as ace or oace Itutvey, we epect (y) > (y) to suggest that y s a ace he R or PCA s ee as: ( y) ( y) > < η

Face Recognition. Face Recognition. Why is Face Recognition. Automated Face Recognition Difficult? Why is it Difficult?

Face Recognition. Face Recognition. Why is Face Recognition. Automated Face Recognition Difficult? Why is it Difficult? Face Recogto Face Recogto If I ook at your face I mmedatey recogze that I have see t before Yet there s o mache whch, wth that speed, ca take a pcture of a face ad say eve that t s a ma; ad much ess that