LuanVanCNTT-TimKiemAnhDuaVaoNoiDung

8/14/2019 LuanVanCNTT-TimKiemAnhDuaVaoNoiDung

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TRNG I HC KHOA HC TNHINKHOA CNG NGH THNG TIN

B MN CNG NGH TRI THC

NGUYN QUC UY - 9912745

TM KIMNH DA VO NI DUNG

LUN VN CNHN TIN HC

GIO VIN HNG DNTh.s L QUC NGC

TP.HCM, 07/2003


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Lun vn tt nghip i hc

LI CM N

Trc tin, em xin chn thnh gi li cm n n Thy L Quc Ngc,

ngi nhit tnh, tn tm, hng dn v kin thc em c th lm c lun

vn ny. ng lc tng chng b b tt trong cng vic, Thy ng vin gip

em mnh dng hon thnh lun vn ny. Mt ln na em xin t lng bit n Thy.

Sau ht, xin gi li cm n n gia nh bn b, ngi thn ng hng

vin tinh thn lun vn c hon thnh.

Xin chn thnh cm n tt c !

TPHCM, 07/2003

Ngi thc hin

Nguyn Quc Uy


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NHN XT CA GIO VIN HNG DN

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NHN XT CA GIO VIN PHN BIN............................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................

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MC LCLI M U

PHN 1: TNG QUAN

1. Shnh thnh bi ton ..............................................................................3

2. Cch tip cn: .............................................................................................3

2.1. c trng mu sc: .................................................................................4

2.2. c trng vn:.........................................................................................4

2.3. c trng hnh dng:..............................................................................4

2.4. o: .......................................................................................................4

2.5. M hnh giao din: ..................................................................................5

PHN 2: CC PHNG PHP TM KIM NH DA VO NI DUNG

Chng 1: Tm kim nh da vo mu sc.................................................9

1. Mu sc: ......................................................................................................10

1.1. Mt s c tnh vt l t bit ca mu sc..........................................10

1.2. H thng mu chun RGB .....................................................................10

1.3. H thng mu CMY................................................................................12

1.4. H thng mu L*a*b...............................................................................12

1.5. H thng mu HSI...................................................................................12

2. Tm kim nh da vo mu sc ................................................................14

2.1. Lt mu ............................................................................................14

2.2. Cc loi o mu sc............................................................................19

Chng 2:Tm kim nh da vo vn..........................................................22


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1. Vn...............................................................................................................23

1.1. Vn l g? ................................................................................................23

1.2. Mt s loi vn tiu biu.........................................................................24

2. Tm kim nh da vo vn........................................................................25

2.1. Mt ca ng bin v hng ca bin...........................................25

2.2. Phn hoch vng nh phn cc b .........................................................27

2.3. Ma trn ng hin v i tng ng hin ..........................................28

2.4. o nng lng ca vn da vo lut o ..........................................31

2.5. Tng quan t ng v quang ph nng lng...................................33

2.6. Phn on vn (Texture segmentation) ................................................34

Chng 3:Tm kim nh da vo hnh dng...............................................35

1. Hnh dng....................................................................................................36

1.1. Khi nim v hnh dng..........................................................................36

1.2. c im hnh dng i vi vic tm kim nh ....................................362. Tm kim nh da vo hnh dng.............................................................37

2.1. Lt hnh dng...................................................................................37

2.2. so khp ng bin ca hnh dng..................................................38

2.3. So khp vi nh pht ha.......................................................................40

PHN 3 CI T V KT QU THNGHIM

Chng 1:Ci t...........................................................................................44

1. Chng trnh ..............................................................................................45

2. Phn Mu sc..............................................................................................46


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3. Phn Vn.....................................................................................................50

4. Phn Hnh dng..........................................................................................53

Chng 2:Kt qu thnghim.....................................................................54

1. Phn Mu sc..............................................................................................55

2. Phn Vn.....................................................................................................73

3. Phn Hnh dng..........................................................................................77

PHN 4 KT LUN

nh gi kt qut c ...........................................................................80

Hng pht trin............................................................................................80Ti liu tham kho .........................................................................................81


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TM TT LUN VN

Tn ti : Tm kim nh da vo ni dung

Tm kim nh da vo ni dung l mt ti nghin cu v kh nng xy dng

mt chng trnh cho php tm kim nh trn mt csd liu nh cho trc. Victm kim ny da trn ni dung ca nhng bc nh trong csd liu. Ni dung

ca mt bc nh c th l mu sc ca bc nh, vn ca bc nh, hay nhng kiu

hnh dng.

Lun vn ny tp trung vo vic nghin cu nhng l thuyt xy dng nn mt

ng dng nh vy, ng thi ng dng l thuyt xy dng nn mt s demo,

cho thy kh nng c th pht trin c thnh ng dng hon thin c.

ti gm c ba phn: tm kim nh da vo mu sc, vn v hnh dng.

Tm kim nh da vo mu sc: cch tip cn chnh l da vo lt mu (colour

histogram)

Tm kim nh da vo vn: cch tip cn chnh l da vo ma trn ng hin (co-

occurrence matrix)

Tm kim nh da vo hnh dng: cch tip cn chnh l da vo s so khp nhpht ha (sketch matching)


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1

LI MUS m rng ca multimedia, cng vi khi lng hnh nh v phim ln, s

pht trin ca nhng xa l thng tin hin ti thu ht ngy cng nhiu nhngchuyn gia i vo nghin cu nhng cng c cung cp cho vic ly thng tin t d

liu nh t ni dung ca chng. Ly thng tin t d liu nh c lin quan n rt

nhiu cc lnh vc khc, t nhng phng trng by tranh ngh thut cho ti nhng

ni lu tr tranh ngh thut ln nh vin bo tng, kho lu tr nh chp, kho lu

tr nh ti phm, c sd liu nh v a l, y hc, ... iu lm cho lnh vc

nghin cu ny pht trin nhanh nht trong cng ngh thng tin.

Ly thng tin t d liu nh t ra nhiu thch thc nghin cu mi cho cckhoa hc gia v cc k s. Phn tch nh, x l nh, nhn dng mu, giao tip gia

ngi v my l nhng lnh vc nghin cu quan trng gp phn vo phm vi

nghin cu mi ny.

Kha cnh tiu biu ca ly thng tin t d liu nh da trn nhng cng b

c sn nh l nhng i tng nhn thc nh mu sc, vn (texture), hnh dng, cu

trc, quan h khng gian, hay thuc v ng ngha cn bn nh: i tng, vai tr

hay s kin hay lin quan n thng tin v ng ngha quan h nh cm gic, cm

xc, ngha ca nh. Tht ra phn tch nh, nhn dng mu, hay x l nh ng mt

vai tr cn bn trong h thng ly thng tin t nh. Chng cho php s trch rt t

ng hu ht nhng thng tin v nhn thc, thng qua phn tch s phn b im

n h v s phn tch o.

Tm kim theo cch thng thng da trn vn bn gi y c b sung bi

truy vn da v o ni dung, nhm vo kha cnh nhn thc thng tin nh. Thc hin

truy vn mc nhn thc i hi nhng phng thc mi, cho php ch nh n

nhng thuc tnh lin quan n th gic cn tm. Giao din ha phi h tr c t

nhng v d nh l nhng mu c sn. Khi ngi dng trong mt vng lp,

m hnh giao din sao cho ngi dng c th truy cp vo s ging nhau gia

nhng i tng.


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2

PHN 1

TNG QUAN


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1. Shnh thnh bi ton:

Bn cnh kho d liu vn bn, kho d liu nh ngy cng trnn khng l

vt qu s kim sot ca con ngi. Khi c nhu cu tm kim mt vi tm

nh no trong mt csd liu hng tr m ngn nh, iu ny kh c th

thc hin c khi ta tm kim bng tay theo cch thng thng, ngha l

xem ln lt tng tm nh mt cho n khi tm thy n h c ni dung cn tm.

Song song vi spht trin ca nhng phng tin k thut s, trong tng

lai, s lng nh s cn tng nhanh hn na, nhiu hn na. Do , nhu cu

tht s i hi phi c mt cng c h trcho vic tm kim ny cng sm

cng tt. V vy ti tm kim d liu nh da v o ni dung ra i gp

phn p ng nhu cu ny.

Tm kim d liu nh da vo ni dung l g? y l mt ch nghin

cu mi trong cng ngh thng tin. Mc ch chnh ca n l ly nhng nh

t csd liu p h hp vi tiu ch truy vn.

Th h u tin ca h thng tm kim nh da vo ni dung cho php truy

cp tr c tip n nh thng qua thuc tnh chui. Nhng tm kim c th

cho nhng h thng dng ny l tm tt c nhng tranh v ca trng

Florentine trong th k th XV hay tm kim tt c nhng tm nh v t

ai ca Cezanne. Metadata ca h thng trong th h u tin da trn

chui, s trnh by, m hnh quan h, cu trc khung. Xem hnh 1.1.

Th h mi ca h thng tm kim nh h tr y vic ly thng tin da

vo ni dung thuc v th gic. Chng cho php phn tch i tng, t ng

trch rt c trng. Xem hnh 1.2.

Nhng phn t thuc v th gic nh l mu sc, vn, hnh dng i tng,

quan h khng gian c lin quan trc tip n kha cnh nhn thc ca ni

dung nh. Ta trc tip nh vo nhng phn t ny trong vic tm kim.

Do , ni dung ca ti s gii quyt nh sau: h thng tm kim nh da

vo ni dung, ba c trng l mu sc,vn v hnh dng. ti ch tp chung

vo demo mt sphng php lm ca tng phn.


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2. Cch tip cn:

ti tip cn theo m hnh thng k.

C ba loi tm kim nh ti tp chung gii quyt l :

- Tm kim nh da vo mu sc.

- Tm kim nh da vo vn.

- Tm kim nh da vo hnh dng.

2.1. c trng mu sc:

Mu sc l vn cn tp chung gii quyt nhiu nht, v mt nh mu th

thng tin quan trng nht trong nh chnh l mu sc. Hn na thng tin v

mu sc l thng tin ngi dng quan tm nht; qua c trng mu sc, c

th lc c rt nhiu lp nh, thng qua v tr, khng gian, nh lng ca

mu trong nh.

2.2. c trng vn:

C nhng lp nh m mu sc khng th gii quyt c, i hi phi dng

c trng vn. V d nh nhng nh lin quan n cu trc ca im nh

nh: c, my, , si.

Vn s gii quyt tt cho vic tm kim i vi lp nh ny.

2.3. c trng hnh dng:

i vi nhng lp nh cn tm m lin quan n hnh dng ca i tng th

c trng vn v mu khng th gii quyt c. V d nh tm mt vt c

hnh dng ellipse hay hnh trn trong nh.

Tm kim theo hnh dng tht s l mt ci ch ca h thng tm kim da

vo ni dung mun t ti.

2.4. o:

C ngha quan trng trong tm kim nh da vo ni dung. o mang

ngha quyt nh kt qu tm kim s nh th no, mc chnh xc.


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2.5. M hnh giao din:

Giao din cng l mt vn ng quan tm ca bi ton tm kim nh. M

hnh giao din da trn m hnh tm kim cho php lp.

y m hnh ngi dng c thc t yu cu tm kim vi nhiu cp .

Qu trnh tm kim c th l mt qu trnh lp i lp li nhiu ln: tm kim,

lc, chnh sa ngng cho n khi t n kt qu nh mong mun. Do

giao din chng trnh phi h trchc nng cho php chn lc kt qu, loi

b nhng kt qu khng ph hp, lu li nhng kt qu va , tm kim

trong kt qu va tm c, thay i mc chnh xc ca vic tm kim.

Hai vn c ti quan tm v giao din tm kim l: m hnh tm kim

theo khng gian ton cc v cc b. i vi c trng mu: giao din cho

php giao tip c ton cc v cc b. c trng vn v hnh dng ti ch

dng li mc ton cc.


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H thng tm kimCh mc

Truy vn bng vnbn

Trnh by ni dung

Ngi dng

Phn hi

Ch thch(lm bng tay)

Hnh 1.1 M hnh ca h thng tm kim th h u tin


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H thng tm kimCh mc

Truy vnbng vn bn

Trnh by ni dung

Ngi dng

Phn hi

Ch thch(lm bng tay)

Hnh 1.2 M hnh ca h thng tm kim th h mi

Truy vnbng vd

Tm ltqua

Trch rt ttrng


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PHN 2

CC PHNG PHP TM KIM

NH DAVONI DUNG


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Chng 1:

Tm kim nh da vo mu sc

1. Mu sc

1.1. Mt s c tnh vt l t bit ca mu sc

1.2. H thng mu chun RGB

1.3. H thng mu CMY1.4. H thng mu L*a*b

1.5. H thng mu HSI

2. Tm kim nh da vo mu sc

2.1. Lt mu

2.2. Cc loi o mu sc


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1. Mu sc:

S nhn thc v mu sc l qu trnh quan trng ca con ngi. S nhn

thc v mu sc ph thuc vo c tnh cht vt l ca nh sng v qu trnh

x l ca th gic vi s gp phn rt quan trng ca kinh nghim. Con

ngi dng thng tin mu sc phn bit i tng, vt liu, n, v tr v

ngay c thi gian ca ngy.

Vi s pht trin mnh m ca cc thit b kinh t, my mc x l mu sc

trnn thng dng: Chng ta c cc thit b nh my quay phim mu, thit

b chiu mu v nhng phn mm x l nh mu. My mc c th dng mu

sc cho nhng mc ch nh l con ngi. c bit, mu sc thun tin bi

v n cung cp php o lng a dng ti mi im nh n, c th phn lp,

phn loi m khng cn n nhng s x l khng gian phc tp a n

quyt nh.

1.1. Mt sc tnh vt l c bit v mu sc:

Con ngi ch c kh nng nhn thc c nh sng c bc xin t vi

bc sng trong khong 400 700 nanomet. C quan th gic cm nhn

c nh sng l do b mt i tng pht ra nh sng, l kt qu ca s

tng tc gia nng lng chiu sng v nhng phn t ca b mt i

tng. Mt i tng mu xanh dng s c b mt mu xanh dng khi

chiu nh sng trng vo. Nhng i tng s c mu tm khi chiu nh

sng vo.

1.2. H thng mu chun RGB:

Mt ngi c th phn bit hng ngn mu sc khc nhau, nhng con s

chnh xc hn vn cn ang c bn ci nhiu. Ba mu RGB (Red-Green-

Blue) m ha h thng ha s dng ba byte (28)3 hay khong chng 16

triu mu phn bit. My tnh c th phn bit bt k mu g sau khi c

m ha, nhng vic m ha c th khng trnh by c nhng s khc bit


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trong th gii thc. Mi im nh RGB bao gm mt byte cho mu R, mt

byte cho mu G v mt byte cho mu B.

Vic m ha mt mu ty trong dy hin thc lm bng cch t hp ba

mu chnh. V d: Red(255,0,0), Green(0,255,0), Blue(0,0,255), Black(0,0,0)

H thng mu RGB l mt h thng mu cng vo bi v mi mu c to

nn bng cch cng thm cc phn t vo mu en(0,0,0)

Khun dng ca khng gian mu RGB l nh dng ph bin nht ca nh

s, l do chnh l tnh tng thch vi mn hnh hin th chnh l mn hnh vi

tnh. Tuy nhin khng gian mu RGB c hn ch ln nht l khng ph hp

vi cch con ngi cm nhn v mu sc. Do khng ph hp cho vic

ng dng vo tm kim nh.

Blue

Green

Red

[1,0,1]Magenta

[1,1,0]Yellow

[0,1,1]Cyan

[0,0,0]

[0,0,1]

[0,1,0]

[1,0,0]

[0,1,1]

White

Hnh 1: Khi mu


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1.3. H thng mu CMY:

H thng mu CMY theo m hnh in trn giy trng v theo khun mu tr

t mu trng thay v thm vo t mu en nh h thng mu RGB.

CMY l vit tt ca Cyan-Magenta-Yellow (mu lc lam, mu ti, mu

vng), l ba mu chnh tng ng vi ba mu mc in. Cyan hp thu s

chiu sng ca mu , Magenta hp thu mu xanh lc, Yellow hp thu mu

xanh dng. Do , to ra s phn nh tng ng nh khi in nh c chiu

sng vi nh sng trng. H thng di dng m tnh v m ha theo dng

hp th mu. C mt s m ha nh sau: trng (0,0,0) v khng c nh sng

trng c hp th, en (255,255,255) v tt c cc thnh phn ca mu trng

u c hp th.

H thng mu CMY dng nh l mt s o ngc ca h thng mu

RGB. c tnh ca n l s n gin, ng dng nhiu trong thc t. Tuy

nhin khuyt im ca n cng tng t nh khng gian mu RGB, tc l

cch m ha khc vi cch m con ngi cm nhn v mu sc. Khng thch

hp cho bi ton tm kim nh da vo ni dung.

1.4. H thng mu L*a*b:

M hnh L*a*b c cbi CIE cho vic lng ha s khc bit ca mu

sc trong vt chiu sng ca nh sng ban ngy. Tuy nhin n c mt s

chuyn i c ghi vo m tnh ton cho vic thch nghi vi nhng

ngun sng.

y l h thng mu c s tch ring nh sng v mu sc ra ring. Do ,

cng c kh nng ln cho vic tm kim da v o ni dung.

1.5. H thng mu HSI: Hue-Saturation-Intensity

H thng mu HSI m ha thng tin mu sc bng cch chia gi tr intensity

I t hai gi trc m ha thuc v hi t ca mu- hue H v saturation

S.


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Thnh phn khng gian mu HSI gm c ba phn: Hue c nh ngha c

gi tr 0-2 , mang thng tin v mu sc. Saturation c gi tr 0-1, mang gi

tr v thun khit ca thnh phn Hue. Intensity (Value) mang thng tin

v sng ca im nh.Ta c th hnh dung khng gian mu HSI nh l vt

hnh nn. Vi trc chnh biu th cng sng Intensity. Khong cch n

trc biu th tp chung Saturation. Gc xung quanh trc biu th cho sc

mu Hue.

i khi, h thng mu HSI c coi nh l h thng mu HSV dng Value

thay vIntensity.

H thng mu HSI th thch hp hn vi mt s thit k ha bi v n

cung cp s iu khin trc tip n nh sng v hue. H thng mu HSI

cng h tr tt hn cho nhng thut ton x l nh v s tiu chun ha v

nh sng v tp chung vo hai tham s v hi t mu, v cng mu.

H thng mu HSI c s phn chia r rt gia nh sng v mu sc. Do

c kh nng rt ln c p dng cho vic tnh c trng v so snh s ging

Hnh 2: Khi nn mu minh ha h thng mu HSI

Green

Blue

Cyan

Yellow

Magenta

Red

[0,0,0]Black

H=2/3Green

Red

H=0

Cyan

H=

BlueH=4/3

H=/3Yellow

IWhite

HS

I=0.5

I=1


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14

nhau v mu sc ca hai nh. Do n rt thch hp cho vic tm kim nh

da vo mu.

S ging v khc nhau gia hai nh v mt mu sc i vi mt ngi ch

mang ngha tng i. Do khi p dng vo bi ton ny trn my tnh

th ta cng gi lp s tng i ny.

Phng php chnh ca vic tm kim theo mu sc l dng lt mu

lm c trng cho tng nh. Do nhng c im ring ca m hnh mu HSI

v c trng ca vic tm kim nn tnh lt mu cng c dng mt m

mnh rt c bit ph hp cho nhng c im ring ny.

2. Tm kim nh da vo mu sc:

Phng php ph bin tm kim nh trong mt tp nhng nh hn tp cho

trc l da vo lt mu ca chng. y l cch lm kh n gin, tc

tm kim tng i nhanh nhng khuyt im l kt qu tm kim li c

chnh xc khng cao. Nhng y c thc xem nh l bc lc u

tin cho nhng tm kim sau. Mun c kt qu chnh xc cao i hi s

kt hp ng thi vi vn (texture) v hnh dng (shape).

Cho n nay, gii quyt vn v mu sc, cch tip cn chnh vn l da

vo lt mu.

2.1. Lt mu:

Lt mu: Nh l mt bng tm tt thng tin v mu sc cho mt nh

mu bt k.

V vic tnh lt mu ny c tin hnh mt cch rt nhanh chng trong

nh m ch qua mt ln duyt qua ton bnh. Do ng dng vo vic tm

kim nh s c li rt ln v mt tc .

Mt s tnh cht cn quan tm ca lt mu i vi vn truy tm nh:

- Vic tnh lt mu ca nh din ra rt nhanh chng trong nh ch qua

mt ln duyt qua ton bnh.


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15

- Lt mu tng i bt bin i vi php tnh tin, xoay nh, v nht l

s ko nh, ko gin, thay i kch thc ca nh.

- Lt mu ca mt nh mu c th l mt cch miu t rt c ngha

cho vic truy tm nh hay nhn dng i tng trong nh

2.1.1. Lt mu thng thng RGB:

i vi nh 256 mu, lt mu ca nh tng ng vi lt mu ca

nh xm.

i vi nh 24 bit mu, lt mu miu t kh nng kt ni v cng

ca ba knh mu R, G, B. Lt mu ny c nh ngha nh sau:

hR,G,B[r, g, b] = N*Prob{R=r, G=g, B=b}

trong N l s lng im c trong nh.

Lt mu dng ny c tnh bng cch ri rc ho tng mu trong

nh, sau l m s im nh ca mi mu.

Khi m s lng mu l c hn, thun tin hn, ngi ta thng chuyn

i ba knh mu thnh mt bin gi tr mu duy nht. Cho mt nh RGB,

mt kiu chuyn i thng c s dng l:

m= r+Nrg+NrNgb

trong Nr,Ng l s lng bin ca mu v mu xanh lc.

iu ny mang li mt lt n duy nht nh sau:

h[m] = N*Prob{M=m}

Mt cch khc tnh lt mu ca nh RGB l ta phn ra thnh 3 lt

ring bit hR[], hG[], hB[]. Khi , mi lt c tnh bng cch m

knh mu tng ng trong mi im nh.

2.1.2. Lt mu HSI:

M hnh mu HSI c nhng u im ln cho vic tm kim hnh nh da vo

ni dung v nht l trong cng vic tm kim da vo mu sc. Nhng nhng

nh mu thng thng c lu tr dng k thut s trong my tnh


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16

thng theo chun RGB, do c c nh mu HSI ta phi qua cng

on chuyn i. Chuyn t h mu RGB sang h mu HSI l mt thut gii

c rt nhiu trong hu ht nhng sch v x l nh cin.


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17

Gi R,G,B l gi tr nhp ca RGB vi gi tr trong khong

[0,1] hay [0,255]

I : Gi tr xut ca cng intensity [0,1]

S : Gi tr xut ca bo ha saturation [0,1]

H : Gi tr xut ca mu sc hue [0,2]

R,G,B,H,I,S: Tt cu l nhng gi tr s thc.

Procedure RGB_to_HSI(in R,G,B; out H,S,I)

{

I:=Max(R,G,B);

Min:=Min(R,G,B);If (I>=0) then

S:=(I-Min)/I;

Else S:=0;

If (S


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18

Theo cc phng php truyn thng, vic to lt mu chn gin bng

cch chia khng gian mu thnh nhng ngn ring bit, sau m nhng

pixel c mu sc ph hp trong nhng ngn ny. Cch lm ny rt n gin,

nhng khng ph hp cho vic so snh, tm kim nh. V nhng thay i nh

viu kin chiu sng, s thay i v cng c th gy nn nhng thay

i ln trong lt mu. Do , hai nh rt ging nhau v mu sc c th

c lt mu hon ton khc nhau.

V d :khng gian mu HSI, thnh phn Hue trong nhiu trng hp mang

gi tr nhng khng th hin c mu sc trong hin th: Khi gi tr

Intensity nm trong khong 0-0.2, Hue mang bt k gi tr no th mu m

mt ngi nhn thy vn l mu en. V vy i vi cc cch tnh lt

mu thng thng, im nh A c Hue bng 2 , Intensity bng 0.1 v im

nh B c Hue bng , Intensity bng 0.1 s nm trong nhng bin khc nhau.

Nhng tht ra, im nh A v im nh B u c gi tr hin th l mu en.

Lt HSI ci tin:

Mt phng php c sut gii quyt cho trng hp trn l ta

da vo Intensity lc trc nhng gi tr m Hue khng th biu thc.

Sau dng Saturation lc nhng gi tr c sc mu xm. Phn cn li

ca khng gian mu ta s chia u mi thnh phn thnh nhng khong nht

nh c s tng ng v mu sc.

gi tr ca lt mu HSI c tnh mt cch ph hp nht i vi vic

tm kim, chng ta cn chia nh khng gian 24 bit mu, tng ng vi 224

mu, xung mt con s c th chp nhn c. Mt con sc ngh l 5

gi tr mc xm, 162 cho gi tr sc mu, tng cng l ta ch cn lu tr 167

bin mu.


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19

Hue v Saturation khi Intensity < 0.33

Hue v Saturation khi Intensity > 0.33

2.2. Cc loi o mu:

Bc tip theo ca qu trnh tm kim d liu nh da vo ni dung l xc

nh trng khp ca hai lt mu va tnh c bc trn. Do ,

pht sinh ra mt gi tr biu th cho s trng khp ny, c nhiu cch

tnh gi tr ny. Ta gi nhng gi trc tnh t nhng cch khc nhau ny

l cc loi o mu.

Mt cch n gin, o mu l c coi mt gi trbiu th cho so

khp s trng khp ca hai lt mu. Ty theo tng trng hp, tng loi

o mu gi tr ny c th m hoc dng ln hoc nh tng ng vi mc

ging nhau nh th no ca cc loi lt mu.


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20

Mi loi o mu c nhng u v khuyt im ring, trong tng trng

hp c th.

Gi h(I) v h(M) tng ng l 2 lt mu ca hai nh I v nh M. Khi

cc loi o mu c nh ngha l mt s nguyn (hoc s thc) theo cc

loi o tng ng nh sau:

2.2.1. o khong cch min-max:

c thc hin da trn tng ly phn giao ca ca hai lt cn so

snh, ta s c mt lt , tnh tng cc gi tr c c t lt ny cho

ta c o min-max.

i vi o min: ta tnh da vo gi tr min ti mi K bin.

Intersection( h(I), h(M) ) = =

K

j 1

min{h(I)[j],h(M)[j]}

i vi o max: ta tnh da vo gi tr max ti mi K bin.


K

j 1

max{h(I)[j],h(M)[j]}

Matching ( h(I), h(M)) =

i i

iMhiIh

MhIhtionInter

]))[(],)[(max(

))(),((sec

2.2.2. o khong cch euclid:

y l cch tnh khong cch clit thng thng gia cc K bin:


K

j 1

2))()(( MhIh

Hoc c th l:


K

j 1

)()( MhIh


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21

2.2.3. o khong cch ton phng:

Intersection(h(I),h(M)) = = =

K

i

K

j1 1

[h(i)-h(j)] aij [h(i)-h(j)]

2.2.3. o c trng s:

dhist(I, Q) = (h(I) h(Q))TA(h(I) h(Q))

trong , h(I) v h(Q) l nhng lt tng ng ca nh I v Q, v A l ma

trn ng dng KxK. Trong ma trn ny, nhng mu m rt ging nhau th

gn vi gi tr mt, cn nhng mu rt khc nhau th s c gi tr gn vi

khng.


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22

Chng 2:Tm kim nh da vo vn

1. Vn

1.1. Vn l g?

1.2. Mt s loi vn tiu biu.2. Tm kim nh da vo vn

2.1. Mt ca ng bin v hng ca bin

2.2. Phn hoch vng nh phn cc b

2.3. Ma trn ng hin v i tng ng hin

2.4. o nng lng ca vn da vo lut o

2.5. Tng quan t ng v quang ph nng lng


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23

1. Vn:

1.1. Vn l g?

Vn (texture), nnyvn cha c mt nh ngha chnh xc c th v vn,

l mt i tng dng phn hoch nh ra thnh nhng vng c quan

tm v phn lp nhng vng .

Vn cung cp thng tin v s sp xp v mt khng gian ca mu sc v

cng ca mt nh.

Vn c c trng bi sphn b khng gian ca nhng mc cng

trong mt khu vc lng ging vi nhau.

Vn ca nh mu v vn i vi nh xm l nh nhau.

Vn gm nhiu vn gc hay vn phn t gp li, i khi c gi l texel.

Xt v vn phn tch vn, c hai c trng chnh yu nht:

- Cu trc vn c nh ngha nh sau: vn l tp hp nhng texelc

sp xp theo mt s quy lut nht nh hay c cu trc khng gian lp i

lp li.

- S thng k vn c nh ngha nh sau: vn l mt o v s lng

ca s sp xp nhng mc xm hay cng sng trong vng.

Cu trc vn: mt vn bt k c th coi nh l mt tp ca nhng texel th

trong mt quan h khng gian c bit no . Mt cu trc khng gian ca

mt vn bt k sau c th bao gm mt s m t ca texel v mt c t

v khng gian. Nhng texel ng nhin phi c phn on v quan h

khng gian phi c tnh ton mt cch tht hiu qu. Texel l nhng vng

nh c th trch rt t mt s hm phn ngng n gin. c im quan h

khng gian ca chng c th miu t nh sau:

Gi s rng chng ta c tp nhng texel, vi mi phn t ca tp hp ny ta

c thc trng bi mt im ngha nht, im ny gi l trng tm. t S

l tp ca nhng im ny. Vi mi cp im P v Q trong tp S, ta c th

xy dng ng phn gic trc giao ni chng li vi nhau. ng phn

gic trc giao ny chia mt phng thnh hai na mt phng, mt trong chng


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24

l tp ca nhng im gn vi P hn v ci cn li l tp nhng im gn vi

Q hn. t HQ(P) l na mt phng gn P hn. Ta c th lp li qu trnh ny

vi mi im Q trong S. a gic Voronoi ca P l vng a gic bao gm tt

c nhng im gn P hn nhng im khc ca S v c nh ngha:

V(P) = HQ(P)QS, QP

1.2. Mt s loi vn tiu biu:

Vn giy Vn Vn dt Vn nc

Vn ct Vn g Vn siGiy th

5% xo Xo ngn Zc Zc

gch lp vn Ca rC


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25

2. Tm kim nh da vo vn:

Trong hu ht cc trng hp, phn on nhng nh tht ra nhng texel kh

hn nhiu i vi trng hp t nhin sinh ra nhng hoa vn thin nhin.

Thay v vy, vic nh lng v s hay thng tin thng k bng s m t cho

mt vn c thc tnh t chnh mc xc, hay mc mu ca chng. Tuy

cch tip cn ny t trc quan nhng n c hiu sut tnh ton cao, hn na

cch tip cn ny cng ph hp vi ng thi cho vic phn on vn v

phn loi vn.

2.1. Mt ca ng bin v hng ca bin:

T khi phng php d bin c ph bin rng v sn gin trong ng

dng vo quy trnh d i tng, n trthnh l b d bin nh l bc tin

quyt trong vic phn tch vn. S lng im nh trong mt vng nh xc

nh trc v mt kch thc cho ta thy c mt s biu th v mt

im trong vng nh . Hng ca nhng ng bin ny cng c th hu

dng trong vic m tc im hoa vn ca vn.

Xt khu vc gm c N im nh. Gi s rng b d bin da trn gradient p

dng vo cho vng nh ny sinh ra hai kt xut ca ca mi im nh p: 1)

ln gradient Mag(p) v 2) phng hng gradient Dir(p). Mt trong

nhng i tng vn rt n gin l sng bin trn mt khu vc c

nh ngha nh sau:

Fedgeness =N

TpMagp })(|{

vi T l ngng nh ngha trc.

Sng bin trn mt khu vc nh gi mt , nhng khng nh gi

c phng hng ca vn.


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26

o ny c thc mrng c th bao gm c mt v phng

hng bng cch dng lt cho c ln gradient v phng hng

gradient. Gi Hmag(R) biu th lt bnh thng ca ln gradient ca

khu vc R, v gi Hdirbiu th lt bnh thng ca phng hng

gradient ca khu vc R. C hai lt ny c s lng bin ln hn mt s

cnh, trnh by nhng nhm ln gradient v nhng nhm ca phng

hng gradient. C hai c tiu chun ha theo kch thc NRca khu vc

nh R. Khi ta c :

Fmag dir= (Hmag(R), Hdir(R))

l mt m t ca vn nh lng ca khu vc nh R.

Xt hai nh 5x5 nh sau:

nh bn tri c mt im cao hn nh bn phi. N c mt cnh trong

mi 25 im nh ca n, v vy s cnh trn mt n v khu vc ca n l

1.0. nh bn phi c 6 cnh trn mi 25 im nh ca n, v vy s cnh trn


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mt n v khu vc ca n l 0.24. i vi lt ln gradient, chng ta

dng hai bin trnh by cho ng bin sng v ng bin ti. Vi lt

phng hng gradient, chng ta s dng ba bin cho ng bin ngang,

ng bin dc v ng bin xo. nh bn tri c 6 ng bin ti v 19

ng bin sng, nn lt ln gradient bnh thng ca n l

(0.24,0.76), ngha l 24 phn trm ca ng bin l ng bin ti, 76 phn

trm ca ng bin l ng bin sng. N cng c xem nh c 12

ng bin ngang, 13 ng bin dc, v khng c ng bin xo, vy lt

phng hng gradient bnh thng ca n l (0.48,0.52, 0.0), ngha l 48

phn trm ng bin l ngang, 52 phn trm ng bin l dc v 0 phn

trm ng bin xo. nh bn phi khng c ng bin ti v c 6 ng

bin sng, nn lt ln gradient bnh thng ca n l (0.0,0.24). N

khng c ng bin ngang, khng c ng bin dc, nhng c 6 ng

bin xo, vy lt phng hng gradient bnh thng ca n l (0.0,0.0,

0.24).

Trong trng hp hai nh ny, o ng bin trn mt n v khu vc th

thch hp phn bit gia chng, nhng trong trng hp tng qut o

lt thng cung cp mt cch m t mnh hn nhiu. Hai lt n-

bin H1 v H2 c thc so snh bi tnh khong cch L1 ca chng.

L1(H1,H2) = =

n

i

iHiH1

21 ][][

2.2. Phn hoch vng nh phn cc b:

Mt cch khc rt n gin, nhng l o vn hu dng l phn hoch

vng nh phn cc b. i vi mi im nh p trong nh, tm im ln cn

c xem xt rng cng intensity ca chng c ln hn ca im nh p

hay khng. Nhng kt qu t tm im nh ln cn c s dng xy

dng nn mt s nh phn tm ch s l b1b2b3b4b5b6b7b8, trong bi=0 nu


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28

cng intensity ca lng ging th i nh hn hay bng vi p v bi=1 trong

trng hp ngc li. Mt lt ca nhng s ny c dng biu th

cho vn ca nh. Hai nh hay hai khu vc nh c so snh bi vic tnh

ton di L1 gia lt ca chng c nh ngha trn.

2.3. Ma trn ng hin v i tng ng hin:

Ma trn ng hin l mt mng C hai chiu trong c dng v ct

tng ng vi mt tp cc gi tr c th c V. V d nh, i vi nh mc

xm V c th l tp nhng mc xm c th c, i vi nh mu V c th l

tp nhng mu c th c. Gi tr ca C(i,j) cho thy rng bao nhiu ln gi tr

i cng xut hin trong vi gi tr j trong mt s quan h khng gian c

nh ngha trc. V d : quan h khng gian c th c gi tr i xut hin lp

tc ngay bn phi ca gi tr j. R rng hn, chng ta s xem xt trng hp

ring trong tp V l tp nhng mc xm v quan h khng gian c

mang li bi vectd, chnh dch chuyn gia im nh c gi tr i v

im nh c gi tr j.

Gi d l mt vectdch chuyn (dr,dc) dr th thay th cho hng v dc

thay th cho ct. Gi V l tp ca nhng mc xm. Ma trn ng hin mc

xm cho nh I c nh ngha bi:

Cd[i,j]= |{[r,c] sao cho I[r,c]=i v I[r+dr,c+dc]=j}|


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Minh ha ni dung ny vi mt nh 4x4 I v ba ma trn ng hin cho I l

C[0,1], C[1,0] v C[1,1].Ch thch C[0,1] : v tr [1,0] c gi tr 2, chnh rng j=0 xut hin hai ln

trc tip bn phi ca i=1 trong nh. Tuy nhin v tr [0,1] c gi tr 0, ch

nh rng j=1 khng bao gixut hin trc tip bn phi ca i=0 trong nh.

0 1 2

0 4 0 2

1 2 2 0

2 0 0 2

0 1 2

0 4 0 2

1 2 2 0

2 0 0 2

0 1 2

0 2 0 2

1 2 1 1

2 0 0 1

i

j

i

j

i j

C[1,1]C[1,0]C[0,1]

1 1 0 0

1 1 0 0

0 0 2 2

0 0 2 2

nh 1

i

j


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30

Gi tr ln nht trong ma trn ng hin l 4 ti v tr [0,0], chnh rng gi

tr 0 xut hin 4 ln trc tip bn phi ca gi tr 0 khc trong nh.

C hai bin tu quan trng ca ma trn ng hin t ma trn ng hin mc

xm chun.

u tin tiu chun ho ma trn ng hin mc xm Nd c nh ngha bi:

Nd[i,j]= i j d jiC

jiCd

],[

],[

Tiu chun ho nhng gi tr ca ma trn ng hin nm gia gi tr 0 v 1.

V do c th xem xt chng di dng xc sut trong ma trn ln.

Th hai l ma trn ng hin mc xm i xng Sd nh ngha bi :

Sd[i,j] = Cd[i,j]+C-d[i,j]

thc cht l mt cp ca nhm ca nhng i xng k cn nhau.

Ma trn ng hin nm bt thuc tnh ca vn, nhng chng khng hu dng

trc tip cho vic phn tch su hn v vn, nh l so snh hai vn. Thay v

vy, nhng i tng s hc ca vn c tnh ton t ma trn ng hin c

thc dng trnh by vn cht ch hn, sc tch hn. Di y l

nhng i tng chun bt ngun t mt ma trn ng hin chun.

Energy = i j

d jiN ],[2

Entropy = -i j

dd jiNjiN ],[log],[ 2


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31

Contrast = i j

d jiNji ],[)(2

Homogeneity = +i j

d

ji

jiN

1

],[

Correlation =ji

i j

dji jiNji

],[))((

Trong ji , l gi tr trung bnh v ji , l lch chun ca hng v

ct i, j.

Nd[i] = j

d jiN ],[

Nd[j] = i

d jiN ],[

Mt vn vi vn lch t ma trn ng hin l bng cch no

chn vctd. Mt gii php c ngh bi Zucker v Terzopoulos ldng kim tra bng thng k 2 chn nhng gi tr ca d m vn c cu

trc nht; l, gi tr cc i ca gi tr:

=i j dd

d

jNiN

jiNd 1

][][

],[()(

22

)

2.4. o nng lng ca vn da vo lut o:Mt cch tip cn khc i vi vic sinh ra nhng i tng vn l

dng nhng mt n cc b m d tm nhng kiu vn khc nhau.

Lut o a ra mt cch tip cn da vo nng lng vn, o lng s lng

bin s ln trong phm vi mt ca s cnh kch thc trc. Mt tp ca


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32

9 mt n 5x5 c dng tnh nng lng vn, c trnh by bi mt

vctgm 9 gi tr cho mi im nh ca nh c mang ra phn tch.

Nhng mt nc tnh t nhng vectdi y :

L5 (Level) = [ 1 4 6 4 1]

E5 (Edge) = [ -1 -2 0 2 1]

S5 (Spot) = [ -1 0 2 0 -1]

R5 (Ripple) = [ 1 -4 6 -4 1]

Tn ca nhng vectni r mc ch ca chng. VectL5 mang li trng

lng trung tm trung bnh a phng. VectE5 d ng bin. VectS5

d im. VectR5 d s gn sng. Mt n 2 chiu c tnh bng tch

nhng cp vecttng ng. V d nh mt n E5L5 c tnh bng tch ca

vectE5 v L5 nh sau:

Bc u tin trong hm Lut o l loi b tt c nhng nh hng ca s

chiu sng bng cch di chuyn mt ca s nhi khp trong nh, v trch

rt ra trung bnh a phng cho mi im nh, cho ra kt qu l mt nh

tin x l, trong cng intensity ca mi im lng ging xp x

khng. Kch thc ca ca s ph thuc vo lp nh loi no; Ngi ta quendng ca s kch thc 15x15 cho nhng khung nh t nhin. Sau qu trnh

tin x l, mi 16 mt n 5x5 c p vo nh tin x l, sinh ra 16 nh lc.

Gi Fk[i,j] l kt qu lc vi mt n th k ti im nh [i,j]. Khi bn

nng lng vn Ekcho b lc kc nh ngha bi:

-1-2012

x [1 4 6 4 1 ] =

-1 -4 -6 -4 -1-2 -8 -12 -8 -20 0 0 0 02 8 12 8 21 4 6 4 1


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Ek[r,c] = +

=

+

=

7

7

7

7

],[c

cj

r

ri

k jiF

Mi bn nng lng vn l mt nh y , trnh by ng dng ca mt

n th k ti nh nhp vo.

Mt khi 16 bn nng lng c sinh ra, nhng cp i xng thch

hp c ni li sinh ra 9 bn cui cng, l s thay th mi cp vi gi

tr trung bnh ca chng. V d nh: E5L5 o c ni dung ca ng bin

ngang, v L5E5 o c ni dung ng bin ngang. Trung bnh cng ca

hai bn o c ton b ni dung ca ng bin ca nh.

C tng cng 9 bn nng lng tng hp l :

L5E5/E5L5 L5S5/S5L5

L5R5/R5L5 E5E5

E5S5/S5E5 E5R5/R5E5

S5S5 S5R5/R5S5

R5R5

1.5: Tng quan tng v quang ph nng lng:

Hm tng quan tng ca mt nh c thc dng d tm

nhng phn t hoa vn ca vn v cng ng thi m t tnh mn/tnh th

ca vn. Hm tng quan tng ( )dcdr, ca mt nh vi kch thc

(N+1)x(N+1) vi mt di d = (dr, dc) l:

= =

= =++

= Nr

N

c

N

r

N

c

crI

dccdrrIcrI

dcdr0 0

2

0 0

],[

],[],[

),(

=],[],[

],[],[

croIcrI

croIcrI d


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Nu vn dng th, khi hm tng quan tng st gim chm;

ngc li n s st gim rt nhanh. i vi nhng vn theo quy tc, hm t

ng tng quan s yu. Khi I[r+dr, c+dc] khng c xc nh r l ng

bao ca nh, mt phng php tnh ton nhng gi trnh o phi c

nh ngha.

Hm tng tng tc lin quan vi quang ph nng lng ca php

bin i Fourier. Nu I[r,c] l hm nh v F(u,v) l bin i Fourier ca n,

2),( vuF c coi nh l quang ph nng lng.

2.6. Phn on vn (Texture segmentation):Bt ko mt vn no, cung cp mt gi tr hay vectgi tr ti

mi im nh, m t vn trong nhng im lng ging ca im nh , c

thc dng phn on nh thnh nhng vng c vn ging nhau. Nh

nhng thut ton phn on nh khc, nhng thut ton phn on vn c hai

loi chnh: cch tip cn da vo vng v cch tip cn da vo ng bin.

Cch tip cn da vo vng c tng chnh l nhm hay phn chia nhng

im nh vi nhng c tnh vn ging nhau. Cch tip cn da vo ngbin c tng l i tm nhng ng bin vn gia nhng im nh n t

nhng s phn b vn khc nhau.


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35

Chng 3:

Tm kim nh da vo hnh dng

1. Hnh dng

1.1. Khi nim v hnh dng

1.2. c im hnh dng i vi vic tm kim nh

2. Tm kim nh da vo hnh dng2.1. Lt hnh dng

2.2. so khp ng bin ca hnh dng

2.3. So khp vi nh pht ha


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1. Hnh dng:

1.1. Khi nim v hnh dng:

Mu sc v vn l nhng thuc tnh c khi nim ton cc ca mt bc nh.

Trong khi , hnh dng khng phi l mt thuc tnh ca nh. Thay v vy,

hnh dng c khuynh hng chnh ti mt khu vc c bit ca nh. Hay

hnh dng ch l bin ca i tng no trong nh.

1.2. c im hnh dng vi vic tm kim nh

Hnh dng l mt cp cao hn mu sc v vn. N i hi s phn bit gia

cc vng tin hnh x l vo ca hnh dng. Trong nhiu trng hp,

s phn bit ny cn thit phi lm bng tay. Nhng s tng ha trong

mt s trng hp c th kh thi. Trong , vn chnh yu nht l qu

trnh phn on nh. Nu qu trnh phn on nh c lm mt cch chnh

xc, r rng v nht l hiu qu th s tm kim thng tin da vo hnh dng

c th c hiu lc rt ln.

Nhn dng nh hai chiu l mt kha cnh quan trng ca qu trnh phn tch

nh. Tnh cht hnh dng ton cc m chn hnh dng nh mc ton cc.

Hai hnh dng c th c so snh vi nhau theo tnh cht ton cc bi

nhng phng php nhn dng theo hoa vn, mu v. S so khp hnh dng

nh cng c th dng nhng k thut v cu trc, trong mt nh c m

t bi nhng thnh phn chnh ca n v quan h khng gian ca chng. V

s hin thnh l mt qu trnh lin quan n th, do nhng phng

php so khp v th c thc dng cho vic so snh hay so khp. S so

khp v th rt chnh xc, v n da trn nhng quan h khng gian hu

nh bt bin trong ton th cc php bin i hai chiu. Tuy nhin, qu trnh

so khp v th din ra rt chm, thi gian tnh ton tng theo cp s m

tng ng vi s lng cc phn t. Trong vic tm kim d liu nh da


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vo ni dung, ta cn nhng phng php c th quyt nh s ging v khc

nhau mt cch nhanh chng. Thng thng, chng ta lun i hi s bt

bin c i vi kch thc ca nh cng nh hng ca nh trong khng

gian. V vy, mt i tng c thc xc nh trong mt s hng. Tuy

nhin, tnh cht ny khng thng c yu cu trong tm kim nh. Trong

rt nhiu cnh vt, hng ca i tng thng l khng i. V d nh: cy

ci, nh ca, ...

o v hnh dng rt nhiu trong phm vi l thuyt ca b mn x

l nh. Chng tri rng t nhng o ton cc dng th vi s trgip ca

vic nhn dng i tng, cho ti nhng o chi tit t ng tm kim

nhng hnh dng c bit. Lt hnh dng l mt v d ca o n

gin, n ch c th loi tr nhng i tng hnh dng khng th so khp,

nhng iu s mang li khng nh sai, v ch nh l vic lm ca lt

mu. K thut dng ng bin th c hiu hn phng php trc, chng

lm vic vi s hin hu ca ng bin ca hnh dng i tng v ng

thi cng tm kim nhng hnh dng i tng gn ging vi ng bin

nht. Phng php v phc ha c th l phng php c nhiu c trng r

rng hn, khng ch tm kim nhng ng bin i tng n, m cn i

vi tp nhng i tng c phn on trong mt nh m ngi dng

v hay cung cp. Ta si vo chi tit trong chng sau m t v hnh dng

i tng.

2. Tm kim nh da vo hnh dng:

2.1. Lt hnh dng:

Lt hnh dng c cho rng ld dng trong tnh ton v nhanh trong thi

hnh. Chng s dng c s so snh v mu sc v vn. Vn chnh l nh ngha

bin cho lt hnh dng c nh ngha. Xem nh hnh dng trong nh lmt

vng nhng gi tr mt trong nh nhphn, trong khi ton th nhng gi tr khc

u l gi tr khng. Mt kiu ca so khp hnh dng nh l so khp hnh chiu


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thng qua hnh chiu ng v hnh chiu nm ca hnh dng. Gi s rng hnh dng

c n hng v c m ct. Mi hng v mi ct l mt bin trong lt hnh dng.

Tng s c lu tr trong mt bin l tng s nhng gi tr 1 c lu tr trong

dng hoc ct tng ng . iu ny a n mt lt gm c m+n bin,

nhng iu ny cng ch c ngha khi tt c nhng nh chng ta xem xt phi c

cng mt kch thc. lm cho vic so khp hnh chiu bt bin i vi kch

thc, s lng bin ca dng v s lng bin ca ct phi n nh. Bng cch nh

ngha nhng bin t gc tri trn n gc phi di ca hnh dng, s chuyn i bt

bin t c. Vic so khp hnh chiu khng bt bin i vi php xoay nh,

nhng n c th lm vic tt vi s xoay nh v s thiu chnh xc thuc v hnh

hc mc nh. Mt cch khc lm n bt bin i vi php quay l tnh ton

theo trc to lp

va nht v xoay chng cho n khi trc chnh l trc nm ngang. V chng ta

khng bit ni u l pha trn cng ca hnh dng, xoay hai kh nng c th xy ra

th. Hn na, nu trc chnh v trc ph c cng chiu di, th 4 kh nng xoay

phi c xem xt. So khp hnh chiu c s dng thnh cng trong tm kim

nh logo.

Nhng kh nng khc xy dng lt thng qua gc tip tuyn ti mi

im nh trn ng bao ca hnh dng. o ny th hon ton t ng v mt

kch thc v bt bin i vi s dch chuyn, nhngncng khng bt bin ivi xoay i tng, bi v gc tip tuyn ctnh t hnh dng i vi mt hng

xc nh. C mt s cch khc nhau gii quyt vn ny. Cch th nht l

xoay hnh dng v trc chnh nh m t trn. Mt cch khc n gin hn l

xoay lt hnh dng. Nu lt c K bin, th s c K kh nng xoay. Nhng v

tr xoay khng ng c th lm nh hng tc ca vic tnh ton, c bit l

trong trng hp lt v nh c kch thc ln. Hoc l lt c th c tiu

chun ho bi cch chn bin vi s m ln nht l bin u tin. Mt vi bin ln

nht nn c th v c th c s tn ti ca nhiu.

2.2. so khp ng bin ca hnh dng:

Thut ton so khp ng bin i hi s trch rt v trnh by ng bin ca c

nh cn truy vn v nh mang ra so khp. ng bin c th c trnh by bi


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mt dy nhng im nh hay c th c xp xbi mt a gic. i vi mt dy

nhng im nh, mt loi so khp c in l dng m t Fourier so snh hai

hnh dng vi nhau. Trong ton hc hm lin tc, m t Fourier l nhng h s ca

dy trin khai Fourier ca hm m nh ngha ng bin ca hnh dng nh. Trong

trng hp c bit, hnh dng c trnh by bi dyca m im.

T nhng dy im ny, mt dy ca vect n v :

kk

kkk

VV

VVv

=

+

+

1

1

v mt dy ca nhng sai phn:

= =k

i

iik VVl1

1 , k>0

00 =l

c th c tnh.

M t Fourier {a-M,...,a0,...,aM} sau c xp xbi:

=

=m

k

lLjn

kkn

kevv

LnL

a1

)/2(

12

)()2(

1

Nhngmt ny c th c dng nh ngha o khong cch hnh dng.

Gi s Q l nh truy vn v I l nh mang hnh dng c so snh vi Q. Gi { Qna }

l dy ca nhngmt Fourier cho nh truy vn, v { Qna } l m t Fourier cho

nh. Khi o khong cch Fourier nh sau:

2/12

),(

=

=

M

Mn

Q

n

I

nFourie aaQId


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40

Nh m t, khong cch ny chbt bin i vi php tnh tin. Numnhng

bt bin khc i hi, c th dng s kt hp vi nhiuhms hc th gii quyt

vn t l, xoay, v im bt u cc tiu ho ),( QIdFourier

Nu m ng bin c trnh by di dng mt a gic, chiud ica cc

cnh v gc gia chng c th c tnh v dng trnh by hnh dng. Mt hnh

dng c th c trnh by bi mt dy nhng im ni lin nhau (Xi, Yi, i ), vi

cp ng thng giao nhau ti im (Xi, Yi) vi gc ln i . Cho mt dy Q = Q1,

Q2, ..., Qn ca nhng im ni lin nhau trnh by ng bin ca i tng truy

vn Q v mt dy tng t I=I1, I2, ..., Im trnh by ng bin ca i tng I, mc

tiu l tm mt nhx t Q ti I m nh x t dy phn on ca nh truy vn ti

dy c chiud i tng tphn on ca nh v sao cho cp ca dy phn on truy

vn gn k m gp ti mt gc c bit nn nh x ti mt cp nhng dy phn

on gn k m gp nhau ti mt gc ' tng t.

Mt k thut so khp ng bin khc l so khp mm do (elastic

matching) trong hnh dng truy vn c lm bin dng trnn cng ging

vi hnh dng nh mu cng tt. S cch bit gia hnh dng nh truy vn v hnh

dng ca nh mu da vo hai thnh phn chnh: (1) nng lng i hi trong qu

trnh bin dng t hnh dng nh truy vn ti mc ph hp nht vi hnh dngtrong nh mu. V (2) s o lng v ging nhau gia hnh dng nh truy vn

sau khi bbin dng khp vi hnh dng trong nh mu.

2.3. So khp nh pht ha :

H thng so khp pht ha cho php ngi dng nhp vo mt bn pht ha

ca nhng ng bin chnh trong mt nh v sau h thng s tm kim nhng

nh mu hay nh xm m c ng bin khp nht. Nhng nh mu c tin x

l nh sau t c mt dng trung gian gi l nh c trch rt (abstractimage).

- p dng php bin i affine gim kch thc nh v kch thc ch

nh trc. Dng mt mt n trung v lc nhiu. Kt qu ca bc ny

cho ra mt nh c tiu chun ha


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- D bin s dng thut ton d tm ng bin da trn gradient. D bin

c tin hnh qua hai bc: nhng bin ton cc s c tm thy trc

tin vi mt ngng ton cc da trn gi tr trung bnh v bin i ca

gradient; sau , nhng ng bin cc b s c chn t ton cc theo

nhng ngng cc b. Kt qu ca bc ny cho ra nh gi l nh c

lc bin (refined edge image).

- Tin hnh lm mnh v rt ngn trn nh c lc bin. Kt qu cui

cng c gi l nh c trch rt.

Khi ngi s dng nhp vo mt bc nh pht ha dng th nh l mt nh truy

vn, n cng ln lt c a qua cc giai on chun ha kch thc, nhphn

ha, lm mnh ho, v rt gn. Kt qu ca qu trnh x l ny cho ra mt nh gi

l bn pht ha u nt. Gi y, bn pht ha u nt phi c so khp vi

nhng nh c trch rt trn. Thut gii so khp l thut gii da vo mi tng

quan. Hai nh s c chia ra lm nhng h thng li vung. i vi mi h

thng li vung ca nh truy vn, tng quan cc b vi h thng li vung

tng ng ca nh csd liu s c tnh. thit thc hn, tng quan cc b

c tnh cho mt vi nhng dch chuyn khc bit trong v tr trong h thng

li trn nhng nh csd liu v gi tr tng quan cc i qua tt c nhng

dch chuyn l k t qu ca cho h thn g li . o s ging nhau cui cngl tng ca mi tng quan cc b. o khong cch l nghch o ca o s

ging nhau ny.

T nhng ch gii trn, n c th c biu din li di dng sau:

))]()),((([

1),(

1 gLgAshiftdaxmQId

Q

nncorrelationg

sketch

=

trong AI(g) quy cho h thn g li g ca nh c trch rt c tnh t nh c

sd liu I,shift(AI(g)) quy cho phin bn c dch chuyn ca h thng li g


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ca cng nh c trch rt, v LQ(g) quy cho h thn g li g ca bn ha u

nt c kt qu t nh truy vn Q.


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43

PHN 3

CI T V

KT QU THNGHIM


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Chng 1:

Ci t

1. Chng trnh

2. Phn Mu sc

3. Phn Vn

4. Phn Hnh dng


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1. Chng trnh:

- Chng trnh gm 3 moun ring cho mi phn: mu sc, vn v hnh

dng.

- Mi phn ca chng trnh c lp trnh trn mi trng Visual C++ 7.0,

vi s h trca th vin lp trnh MFC, mt th vin lin kt tnh .dll ca

intel h trcho vic truy xut nh jpeg.

- Mi phn l mt bn demo cho csl thuyt c nu phn 2.

- Phn mu sc, chng trnh demo tp chung vo phn mu sc l nhiu

nht, v y l phn kh thi v c th ng dng c lin vo thc t vi tc

v kt qu chp nhn c.

- Phn vn: chng trnh lm phn tm v so snh vn da vo k thut ma

trn ng hinv thng k khc bit lt xm.

- Phn hnh dng: chng trnh lm phn so khp nh pht ha kt hp vi

lt hnh dng.


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2. Phn mu sc:

Quy trnh thc hin nh sau:

Bc 1: Nhn vo nh mu, tnh lt mu HSI cho nh mu

Bc 2: c nh t csd liu:

Nu cn nh: Tnh lt mu ca nh, qua Bc 3

Nu ht nh: Kt thc

Bc 3: So snh 2 lt mu va tnh c da vo o no .

Bc 4: So snh kt qu o vi ngng, thng bo kt qu.

Quay li bc 2.

Tnh lt mu:

M hnh mu c ng dng vo vic ci t l m hnh mu HSI.

Cu trc ca lt mu nh sau:

struct ColorHistogram

{

unsigned int grey[5]; (1)

unsigned int val[18][3][3];

}

Qu trnh tnh lt mu HSI cho vic tm kim:

Bc 1: Nhn vo nh RGB, i sang nh HSI

Bc 2: c gi tr im tip theo

Nu khng c im th kt thc.

Nu tn ti im, qua bc 3.

Bc 3: c thnh phn intensity.

Nu intensity < 0.3 th cho y l im mu en. Quay li bc 2

Nu intensity>=0.3, qua bc 4

Bc 4: c thnh phn Saturation

Nu Saturation


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Nu Saturation>=0.08 th cho y l im nh mu, gn gi tr tng

ng cho lt mu da vo thnh phn Hue, Saturation, v

Intensity.

Quay li bc 2.

2.1. Tm kim theo t l phn trm v mu sc:

- Ngi dng xc nh t l phn trm mt s mu cn tm kim, nhng

khng quan tm n v tr xut hin ca nhng mu ny. Chng c th xut

hin khp ni trong nh hoc tp chung ti mt khu vc no .

V d: Tm kim nhng bc nh c cha khong 20-30% mu , 30-50%

mu trng, 10-40% mu en.

- Cch tin hnh: Khng cn phi tnh lt mu m ch cn m s lng

nhng mu c chn tm kim.

+ Mu c tm kim c xp vo mt trong 167 bin ca (1)

+ Trong qu trnh tm kim, nu im nh no nm trong bin c mu

c chn th s lng trong bin tng thm 1.

+ Nu t l tng sim nh trong tng bin c chn trn tng s

lng im nh ca nh nm trong khong c t ra th nh tha

mn yu cu tm kim.

2.2. Tm kim theo lt mu ton cc da trn nh mu:

- Ngi dng chn mt nh, nhng nh tm c l nhng nh c sc mu

gn ging vi nh cn tm nht theo mt ngng t chn trc.

- Cch tin hnh: tng cch lm l so snh lt mu ton cc ca nh

vi nhng nh khc trong csd liu. Nu nh trong csd liu c lt

mu ph hp vi o theo mt ngng nht nh sc chn.

+ Tnh lt mu ca nh gc nh (1).

+ Trong qu trnh tm kim, tnh lt mu ca tng nh. Sau so snh

nhng lt ny vi nhau theo cc loi o c chn.


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+ Nhng nh tha mn nhu cu tm kim l nhng nh c s giao nhau ca 2

lt t gi tr tha mn ngng.

o c dng : Min-Max, Euclid, o khong cch ton phng.

2.3. Tm kim theo mu chnh dng li:

- Ngi dng xc nh v tr nhng khong mu s xut hin trong tm nh.

Nhng vng mu c chn di dng li. Ngi dng c th xc nh

chia nh ca tng li.

- Cch tin hnh : Da vo nhng li ca ngi dng n nh, tin

hnh chia nh trong csd liu cn theo nhng li. Dng mi mu i

din cho mt li, tin hnh so snh li m ngi dng n nh vi

li trong nhng nh va xc lp cho ra c theo mt ngng nh trc.

+ Xc nh mc chia nh ca mc li. ng thi xc nh nhng mu

c chn trong cc mt li.

+ Tng t nh trn, mu trong nhng mt li ny sc xp vo 1 trong

167 bin nh trong (1).

+ Trong qu trnh tm kim, nh tm kim sc chia theo ng t l ca

li xc lp trn.

+ ng vi nhng li c mu c chn, tnh lt mu ca li

tng ng trn nh. Tnh mu i din trong li ca nh. Sau tin hnh

so snh mu ny vi mu c chn trong li ban u.

+ Tng nhng so snh li trn so vi mt ngng s cho c kt qu

nh c ph hp hay khng.

2.4. Tm kim ton cc theo dng so snh li da trn nh mu:

- Ngi dng chnh nh mu vi yu cu l: Tm nhng nh c sc mu

gn ging vi nh ny. Cch tm kim ny khc vi cch tm kim da trn

lt mu l n quan tm n v tr ca nhng khong mu trong nh.


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Cch tm kim ny khng nhng tm ra nhng nh c sc mu gn ging vi

nh mu m cn ging nhau v tr tng ng nhng sc mu .

- Cch tin hnh: tng phng php ny ging nh phng php so snh

li cc b c tng tc vi ngi dng.

+ Chia li cho nh mu. Tnh nhng mu i din cho tng li. To

thnh mt mng nhng mu i din.

+ Trong qu trnh tm kim nh, mi nh tm kim ta cng tin hnh chia

thnh nhng li v tnh mu i din cho mi li. Ta cng c mt

mng nhng mu i din.

+ Tin hnh so snh mng mu i din vi ngng cho trc.

2.5.Tm kim kt hp gia mu chnh dng li v ton cc theo mt nh

mu:

- y l s kt hp gia phng php tm ton cc theo dng li v tm cc

b theo dng li. Tng t nh tm ton cc theo dng li nhng cn cho

php ngi dng thay i khong mu ca tng li. Nhng li khng

b thay i khong mu s dng khong mu ca nh mu c chn.

- Cch tin hnh:

+ Tng t nh trn, tin hnh chia li trn nh mu.

+ Nhn nhng gi tr ca mu b thay i trn li. c mng nhng

mu i din.

+ Trong qu trnh tm kim, mi nh tm kim c chia li theo t l tng

ng nh trn. Sau , tnh mng mu i din.

+ Tin hnh so snh mng mu i din ny vi nhau tm ra c nh ph

hp vi yu cu tm kim


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3. Phn vn:


Bc 1: Nhn vo nh mu, tnh vectvn c trng cho nh mu


Nu cn nh: Tnh vectca nh, qua Bc 3

Nu ht nh: Kt thc

Bc 3: So snh 2 vectvn va tnh c da vo o no .


Quay li bc 2.

3.1. Tm kim nh da vo ma trn ng hin:

K thut dng ma trn ng hin i vi vic tm kim nh, qua , vn ca

mi nh c t trng bi mt vectvn, vectny c 5 thnh phn, gi tr

ca mi thnh phn tng ng vi nhng thnh phn ca cc cng thc di

y.

Cng thc c p dng:

Energy = i j

d jiN ],[2

Entropy = -i j

dd jiNjiN ],[log],[ 2

Contrast = i j

d jiNji ],[)(2

Homogeneity = +i j

d

ji

jiN

1

],[


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Correlation =ji

i j

dji jiNji

],[))((

Cc bc tnh ma trn ng hin nhsau:Bc 1: nh mu nhn vo c chuyn sang nh xm (intensity)

Bc 2: Tnh ma trn ng hin trn nh mc xm ny.

Sau bc ny c th c thm bc 2.

Bc 2: Chun ho ma trn ng hin.

Bc 3: Tnh cc gi tr Energy, Entropy, Constrast, Homogeneity,

Correlation.

Bc 4: Gn cc gi tr va tnh c cho vectvn t trng.

3.2. Tm kim nh da vo thng k khc bit lt xm:

K thut ny cng tng t nh i vi ma trn ng hin, nhng n

thng mang li kt qu tm kim kh quan hn nhiu, tc t cng nhanh

hn i vi ma trn ng hin. Vectvn ca trng hp ny cn g c 5

thnh phn chnh, mi thnh phn tng ng vi cc gi tr ca cng thc

di y:Gi h[I] l lt xm ca nh.

Mean = =

255

1

][*i

ihi

Variance = =

255

1

2 ][*)(i

ihmeani

Skewness =3

255

1

3

)var(

][*)(

iance

ihmeanii

=


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Kurtosis = 34

][*)(255

1

4

=i

ihmeani

Entropy = =

255

1

])[ln(*][i

ihih

Cc bc tnh thng k khc bit lt xm nhsau:

Bc 1: nh mu c chuyn sang nh dng xm

Bc 2: Tnh lt xm cho nh xm va tnh c

Bc 3: Tnh cc gi tr mean, variance, skewness, kurtosis, entropy da vocc biu thc trn.

Bc 4: Gn cc gi tr va tnh c vo vect


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4. Phn hnh dng:


Bc 1: Nhn vo nh mu pht tho.

Phn on nh bng ngng.

Tnh lt hnh dng cho nh va phn on


Nu cn nh: Phn on nh, tnh lt hnh dng, qua Bc 3

Nu ht nh: Kt thc

Bc 3: So snh 2 lt hnh dng va tnh c da vo o no .


Quay li bc 2.


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Chng 2:

Kt qu thnghim

1. Phn Mu sc

2. Phn Vn

3. Phn Hnh dng


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1.Phn mu sc:

Mt s kt qu th nghim mt s chc nng chnh ca chng trnh.

Csd liu th nghim: hn 800 nh mi th loi.

1.1.Tm kim vi chc nng tm kim da trn lt ton cc:

nh a vo tm kim:

Ngng ban u c chn l 50, cho ra kt qu tm kim nh sau:


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Sau khi i ngng li l 60, v tm kim trong kt qu va tm c, lp li qu

trnh tm kim, ta thu c kt qu nh sau:


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1.2.Tm kim vi chc nng tm kim da trn phn trm mu:

Nhp vo: Chn mu xanh blue (128,128,255), vi t l phn trm xut hin trong

nh l t 20-40%. Kt qu thu c nh sau:


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1.3.Tm kim vi chc nng tm kim da v tr mu sc trong khng gian:

Chn ngng l 70, v tr mu sc : na trn ca nh l mu trng

Kt qu thu c nh sau:


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2. Phn vn:

2.1. Ma trn ng hin:

Vn c a vo kim tra:

Vi mc ngng l 0.06

Kt qu thu c l:


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2.1. Thng k khc bit vi lt xm:

Vn c a vo kim tra:


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Vi mc ngng l 0.06

Kt qu thu c l:


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3. Phn hnh dng:

Rt tic l k t qu thu c khng kh quan lm.


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PHN 4

KT LUN


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nh gi kt qut cNgi dng c th dng chng trnh ny tm kim nh theo mu sc,

vn, v hnh dng. Vic tm kim nh vi tiu ch mu c kt qu tt. Ph

hp vi th gic ngi. Vic s dng sng to mt h thng tnh ton lt

mu HSI mi lm cho vic tm kim nh da vo mu sc t kt qu tt.

C th tm kim theo mu vi rt nhiu tiu ch t ra.

Tm kim nh theo vn v hnh dng, chng trnh cn ssi, cha p ng

c. V thc s y l hai mng ti r t kh, cn c nhiu s u t

nghin cu hn.

Hng pht trin- Kt hp cc chc nng mu sc, vn, hnh dng li vi nhau gip vic

tm kim c hiu qu hn. S kt hp gia cc chc nng ny vi nhau

s mang li kt qu kh quan hn nhiu, v n lm tng kh nng tm kt

qu chnh xc, theo nh mong mun.

- T chc thnh database nh i vi nhng s lng nh ln c nh.

iu ny s gip cho tc tm kim t gi tr cc tiu.

- C thpht trin thm ng dng c vo thc t:

o Gip tm hng ho trong siu th da vo hnh nh.

o

o Tm nh trn mng.

o ....


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Ti liu tham kho

[1] Linda G.Shapiro, George C.Stockman

COMPUTER VISION

Upper Saddle River, New Jersey

Prentice-Hall, Inc 2001

[2] Ratael C.Gonzalez, Richard E. Woods

DIGITAL IMAGE PROCESSING

Addison-Wesley Publishing Company, Inc 1993

[3] Marius Tico, Taneli Haverinen, Pauli Kuosmanen

A METHOD OF COLOR HISTOGRAM CREATION FOR IMAGE

RETRIEVAL

Signal Processing Laboratory

Digital Media Institute

Tampere University of TechnologyP.O. BOX 553, FIN-33101, Tampere, FINLAND, [email protected]

[4] Charles E. Jacobs, Adam Finkelstein, David H. Salesin

FAST MULTIRESOLUTION IMAGE QUERYING

Department of Computer Science and Engineering

University of Washington

Seattle, Washington 98195


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