nghiên cứu kĩ thuật xử lý video số, ứng dụng vào theo vết và phân loại đối tượng

7/30/2019 nghin cu k thut x l video s, ng dng vo theo vt v phn loi i tng

1/80

I HC QUC GIA TP. H CH MINH

TRNG I HC KHOA HC TNHIN

KHOA CNG NGH THNG TI N

NGUYN DUY NGHA - 0012612

NGHIN CU K THUT XL VIDEO S, NG DNG VO THEO

VT V PHN LOI I TNG

LUN VN CNHN TIN HC

GIO VIN HNG DN

TH.S NGUYN TRI TUN

NI N KHA 2000 - 2004

PDF created with FinePrint pdfFactory Pro trial version http://www.fineprint.com
http://www.fineprint.com/http://www.fineprint.com/


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LI CM N

Trc tin ti xin cm n thy Nguyn Tri Tun ngi hng dn ti

thc hin ti ny. Nhc s tin tng, ch bo tn tnh ca thy ti lun vn

ny hon thnh.

Con xin gi tt c lng bit n, qu trng n ng b, cha m v cc ngi

thn trong gia nh ht lng nui con n hc v lun lun bn cnh con

ng vin con khi con gp kh khn

Em xin cm n tt c cc thy c trong trong trng Khoa Hc T Nhin

v c bit l cc thy c trong Khoa Cng Ngh Thng tin nhit tnh ging

dy v truyn t nhiu kin thc qu bu cho em.

Ti xin chn thnh cm n bn b trong lp cng nh cc anh ch kha

trc cho gip ch bo tn tnh, c bit l anh Trng Thin nh gip

ti nhiu mt v thit b cng nh ti liu

y l mt hng nghin cu mi v rt kh, vi thi gian tip cn kh

ngn trong vng 6 thng v nng lc ca ngi lm ti cho nn ti chc

chn cn nhiu thiu st. Huy vng s nhn c nhiu li ng gp ti

ny hon thin hn

Tp HCM thng 7 nm 2004Sinh vin thc hin

Nguyn Duy Ngha



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CHNG 1_____________________________________________ 1

MU_________________________________________________ 1

1.1 Tng quan____________________________________________ 1

1.2 Yu cu bi ton ______________________________________ 2

1.3 B cc lun vn_______________________________________ 2

CHNG 2_____________________________________________ 4

TNG QUAN V VIDEO V CC K

THUT XL VIDEO CBN____________ 4

2.1 Khi nim v video ______________________________________ 5

2.2 Khi nim v video tun t____________________________ 5

2.2.1 Tn hiu video tun t _________________________________ 5

2.2.2 Cc chun video tng t ______________________________ 8

2.2.3 Cc thit b video tng t _____________________________ 8

2.3 Khi nim v video s _________________________________ 9

2.3.1 Tn hiu Video s _____________________________________ 9

2.3.2 Cc chun video s ____________________________________ 9

2.3.3 Nhc im ca video s ______________________________ 11

2.3.4 u im ca video s _________________________________ 11



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2.3.5 Cc phng php xl trn video s ____________________ 12

2.3.5.1 Pht hin chuyn ng ______________________________ 12

2.3.5.2 c lng chuyn ng _____________________________ 19

CHNG 3____________________________________________ 25

THEO VT V PHN LOII TNG 25

3.1 Bi ton theo vt v phn loi i tng_______________ 26

3.2 M hnh xl bi ton________________________________ 27

3.3 Tin xl____________________________________________ 28

3.4 Pht hin chuyn ng _______________________________ 28

3.5 Theo vt i tng ___________________________________ 37

3.5.1 Don v tr ca i tng trong tng lai ______________ 38

3.5.2 So khp i tng____________________________________ 38 3.5.3 Theo vt i tng ___________________________________ 41

3.5.4 Cp nht i tng___________________________________ 45

3.6 Phn loi i tng __________________________________ 45

CHNG 4____________________________________________ 48

CIT CHNG TRNH____________________ 48

4.1 Mi trng ci t ___________________________________ 49



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4.2 Cu trc chng trnh _______________________________ 49

4.2.1 Cu trc dliu _____________________________________ 49

4.2.2 Cu trc chng trnh ________________________________ 51

CHNG 5____________________________________________ 52

KT QUV HNG PHT TRIN_______ 52

5.1 Kt qut c ____________________________________ 53

5.1.1 Dliu thnghim___________________________________ 53

5.1.2 Kt qut c ____________________________________ 53

5.2 Hng pht trin ____________________________________ 54

TI LIU THAM KHO _________________________ 55

PHLC 1____________________________________________ 56

MT VI HNHNH VKT QUT

C___________________________________________________ 56

1. Mt vi mt n chuyn ng____________________________ 56

2. Kt qu theo vt i tng _____________________________ 63 3. Kt qu theo vt i tng l ngi _____________________ 66

PHLC 2____________________________________________ 69



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VI NT VTHVIN INTEL OPENCV69

1. OpenCV l g? _________________________________________ 69

2. Cc chc nng ca thvin OpenCV ___________________ 69

2.1 Cc kiu dliu cbn _______________________________ 69

2.2 Cc hm xl trong OpenCV __________________________ 71

2.2.1 Cc hm x l cc kiu d liu cbn _____________________ 71

2.2.2 Cc hm v x lnh __________________________________ 72

2.2.3

Cc hm v phn tch vn ng v theo vt i tng _________ 73

2.2.4 Cc hm v nhn dng i tng _________________________ 73

2.2.5 Cc hm v giao din v thu nhn video ___________________ 73



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1

CHNG 1

MU

1.1 Tng quan

Hin nay phn ln lng thng tin con ngi thu vo l di dng hnh

nh. Thng tin di dng hnh nh l thng tin trc quan nn con ngi d dng

tip nhn n. Vi s ra i ca nhiu my mc k thut hin i nh l my nh

s, my quay s, cc my thu hnh, my vi tnh ... th lng thng tin con ngi

thu c ngy cng nhiu. Con ngi khng ch mun tip thu thng tin mt

cch thng m phi bit x l n, lm cho n hu ch hn. Do con ngi

tin hnh nghin cu cc phng php x l trn thng tin trc quan ny chng ta c th tip nhn ti a lng thng tin trc quan ny. Vic x l nh s

ra i vo nhng nm 1960 vi nhiu hng khc nhau nh l nn nh, nhn

dng ..., trong khi vic x l video ch xut hin vo cc thp k gn y cng

vi s ra i ca nhiu trang thit b k thut mi v hin i. Ngy nay trn th

gii vic nghin cu vnh s v video s pht trin rng ri. Cc trng i

hc u c mt ngnh ring nghin cu vn ny gi l ngnh th gic mytnh( computer vision ). Tuy vy vn ny vn cn mi Vit Nam v thiu

cc thit b h trv ti liu, v y l mt hng pht trin mnhiu ha hn

v cng nhiu thch thc. Hin nay Vit Nam cc h thng gim st Vit



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2

Nam cha pht trin lm v ch yu vn da vo con ngi. Tuy nhin trong vi

nm na khi kinh t v khoa hc k thut pht trin th cc h thng gim st ny

cng s pht trin theo. Vic nghin cu v x l video strong khoa c tin

hnh cch y mt nm vi cc ti v gim st giao thng v theo vt i

tng bng li... Vi mong mun tham gia vo hng nghin cu cn mi ny

v gip cc h thng gim st t hiu qu cao hn v gim c chi ph con

ngi chng ti thc hin ti nghin cucc kthut xl trn video s

ng dng vo theo vt v phn loi i tng.

1.2 Yu cu bi ton

Bi ton theo vt v phn loi i tng c chia thnh hai phn.

y chng ti tp trung vo nghin cu phn mt l phn theo vt i tng.

V theo vt i tng ta cn phi thc hin cc phn sau:

Rt trch i tng chuyn ng. Trong phn ny ta phi tch cc

i tng chuyn ng ra khi khung cnh.

Theo vt i tng. Vi tng i tng ta phi lu li c quo

ca chng khi chng vo vng quan st ca taV phn loi i tng, chng ta phi phn bit c cc loi i tng

trong khung cnh quan st ca chng ta. y l phn loi i tng l ngi i

b v cc i tng khc nh l xe...

1.3 B cc lun vn

Da vo cc yu cu trn chng ti chia lun vn thnh 5 chng

Chng 1: MuChng 2: Tng quan v video v cc kthut xl video s: nhm gip

chng ta hiu r hn v video s v cc kthut cbn nht trong x l video s.



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3

Chng 3: ng dng vo bi ton theo vt v phn loi i tng:

trong phn ny ta s p dng cc kkin thc nghin cu c vo gii mt

bi ton trong x l video d l theo vt i tng.

Chng 4: Ci t thnghim

Chng 5: Cc kt qut c v hng pht trin: chng ny trnh

by cc kt qut c trong vic gii quyt bi ton trn v hng pht trin

trong tng lai.



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4

CHNG 2

TNG QUAN V VIDEO V CC K

THUT XL VIDEO CBN



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5

2.1 Khi nim v video

Video hay cn gi l chui nh( image sequence ) tng trng cho

thng tin hnh nh. l mt chui cc hnh nh truyn lin tc theo thi

gian

S = f(x,y,t)

trong :

x,y R: l ta ca im nh (thng tin v khng

gian)

t R: thng tin v thi gian

Da trn cng thc trn ta thy nh tnh l mt trng hp c bit ca

Video. Khi n l mt chui cc nh khng thay i theo thi gian.

f(x,y,t1) = f(x,y,t2); i,j R, x,y R

Video thng c thu, lu tr, v chuyn i dng tun t (analog)

nn chng ta s bt u t video tun t.

2.2 Khi nim v video tun t

2.2.1 Tn hiu video tun t

Tn hiu video tun tc xem nh l tn hiu in 1 chiu theo thi

gian f(t) v c ly mu theo chiu dc.

Vic ly mu theo chu k ny c gi l qut( scanning ). Cc

phng php qut thng c s dng nht l qut lin tc (progressive

scanning) v qut xen k (interlace scanning)



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Qut lin tc(progressive scanning)

H1: Qut lin tc. Cc dng qut bt u t A n B, tip tc n C v c

th cho n D ri quay trli D

o Mi nh hay cn c gi l frame l d liu c ly mu

theo thi gian.

o Mi nh ny c qut lin tc tng dng ngang v t trnxung di vi tc l t giy.

o Phng php qut ny thng c dng trong cng nghip

my tnh vi tc t = 1/72 giy.



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7

Qut xen k

H2: Qut xen k. Dng qut bt u t A n B, chuyn qua C v tip tc cho

n khi ti D s trv E v tip tc qut n F

V mt ngi pht hin ra hnh nh chp khi tn s qut di

50Hz nn tn s qut ca my bao gicng phi ln hn 50Hz. Tuy nhin

khi p dng trong cc nghnh cng nghip khc nh l nghnh truyn thng

th gp kh khn v vn bng thng do kch thc qu ln. T xut

hin phng php qut xen k. Phng php ny chia dng qut thnh dng

chn v dng l ( gi l field ) v qut cc dng chn trong khong t richuyn qua qut cc dng l. V th tn s qut s gim i mt na.

Mt vi thng s quan trng ca tn hiu video l :

o phn gii theo chiu dc ( vertical resolution ): thng s

ny c lin quan n s dng qut trn 1 frame.

o T l co ( aspect ratio ): t l gia chiu rng v chiu cao ca

frame.



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8

2.2.2 Cc chun video tng t

Component Analog Video: chun video ny s dng cc thnh phn

mu RGB hoc l YCrCb( YIQ hoc l YUV )

Composite Video:

o NTSC ( National Television Standards Committee ): xut

hin vo nm 1952, hin ti c s dng Bc M v Nht.

C 262.5 dng trn 1 field hay l 525 dng trn 1 frame, 60

field trn 1 giy v c t l co l 4:3

o PAL ( Phase Alternating Line ) v SECAM ( SEquential

Color And Memory ): c pht trin vo nhng nm 1960

v ngy nay thng c s dng Chu u. Vit Nam

cng dng chun ny. Cc thng s k thut: 625 line trn 1

frame, 50 field trn 1 giy.

2.2.3 Cc thit b video tng t

Cc thit b video tng t c thc chia lm 3 loi. Loi dnh cho

truyn thng. Loi c cht lng chuyn nghip. Loi dnh cho ngi tiudng.

Video c quay bi my quay thng thng v c lu trong bng

hoc c quay bi cc my quay dng trong phim trng v to thnh

phim ( 24 frame/giy ).

Hu ht tn hiu video tng tc lu da trn k thut t ngoi tr

a laser l dng k thut quang.



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9

2.3 Khi nim v video s

2.3.1 Tn hiu Video s

Tn hiu video sc lu tr di dng s. Do chng c ly

mu v lng t ha. Tn hiu video s l mt thng tin 3 chiu gm 2 chiu

khng gian v 1 chiu thi gian hay cn c gi l chui nh s vi mi nh

s l mt nh c ly mu v lng t ha.

chiu thi gian

chiu dc

chiu ngang

H3: chui nh

2.3.2 Cc chun video s

Vic trao i gia cc ng dng v cc sn phm video s a ra

cc chun video s. Cc chun ny bao gm :

Chun nn: dng trao i thng tin trong dng nn ca

video

Chun cc phn gii hin th: c dng trong cng

nghip my tnh.

Chun studio s: c dng trong ngnh cng nghip ti vi

Chun vgiao tip mng c dng trong cng nghip

truyn thng



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10

H4: cc chun v studio s



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11

H5: Cc chun vnh v video s nn2.3.3 Nhc im ca video s

Nhc im ca video s l n i hi khi lng lu tr ln v bng

thng rng truyn ti. Chng ta hy th lm mt php tnh. Vi tn hiu TV

cht lng tt ta cn 1440 im nh trn mt dng, 1050 dng cho mt frame

sng, 720 im trn mt dng v 525 dng trn mt frame sc mu. Bi v mi

giy c 30 frame v 8 bit/ pixel nn kt qu cui cng l xp x545 Mps. y l

mt yu cu qu ln. Do hin nay ngi ta ang nghin cu cc phng php

nn video gim kch thc khi truyn ti.

2.3.4 u im ca video s

Tuy c nhc im v yu cu b nhln nhng video s li c nhiu u

im quan trng. Video tun t cung cp cho chng ta mt s rt gii hn cc

hot ng tng tc nh l : chn knh, chnh ti lui hay l quay chm trn bng

video. Ngoi ra hin th tn hiu theo chun ny v d NTSC trn mt h my

dng chun khc v d PAL ta cn c mt b chuyn i tn hiu t tin. Vi tn

hiu s ta khng cn phi chuyn i cc tn hiu ny. Ngoi ra ta cn c th



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12

chnh sa, to cc hiu ng p trn tn hiu video s. Video s khng ch c vai

tr gii tr m n cn cung cp cho chng ta nhiu thng tin quan trng trong

nhiu lnh vc nh l cc nh gim st qun s, iu khin giao thng, v rt

trch thng tin t cc d liu nh v video.

2.3.5 Cc phng php xl trn video s

Video s c nhiu thng tin trc quan hn l nh s. L do chnh l do

video s c cha thng tin v chuyn ng trong khi nh s ch l nh chp mt

cnh tnh. Cc chui nh ng lun hm cha cc thng tin v chuyn ng, cc

chuyn ng ny l mt tn hiu nhy cm i vi th gic con ngi. Con ngi

c th d dng nhn bit c cc i tng ngay khi chng chuyn ng thm

ch chng rt kh thy khi ng yn. V th cc phng php x l video s cng

khc so vi cc phng php x lnh s. Vn ng l thng tin quan trng

trong x l video s bi v vn ng mang rt nhiu thng tin v mi quan h

khng gian v thi gian gia cc i tng trong nh. Cc phng php cbn

trong x l video s l pht hin chuyn ng v c lng chuyn ng. Pht

hin chuyn ng thng c p dng trong cc h quan st( pht hin itng di chuyn hoc l ng yn ), cn c lng chuyn ng thng c p

dng trong nn video s. Ngoi ra cn c cc phng php x l khc c p

dng vo mc tin x l nh l lc nhiu... cc phng php ny p dng trn

tng frame ging nh trong x lnh s.

2.3.5.1 Pht hin chuyn ng

a. Snt v chuyn ng

Chuyn ng theo cc khi nim trong vt l l s thay i v tr

gia vt ny v vt kia. Tc l khi xt ti s chuyn ng th ta phi xt l n

chuyn ng so vi ci g. Khi xt ti chuyn ng ta thng t n vo mt h



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quy chiu qun tnh. Mt vt c thng yn trn h quy chiu ny nhng li

chuyn ng khi xt n vi h quy chiu khc. V d khi ta ng yn th c th

coi l ta ng yn so vi h quy chiu gn vi tri t, nhng khi a vo h

quy chiu gn vi mt tri th ta li chuyn ng. iu ny c ngha rt quan

trng khi ng dng vo camera ng. Chuyn ng trong thc t l chuyn

ng 3D nhng khi con ngi tip nhn th n trthnh chuyn ng 2D. Ni

chung hnh nh m mt ngi nhn c u l 2D ht. V php ton chuyn i

nh 3D thnh nh 2D m mt con ngi cm nhn c l php chiu phi cnh.

H6 Php chiu phi cnh ca mton thng

Chuyn ng trong th gii thc 3D qua php chiu phi cnh s

bin thnh chuyn ng trong mt phng 2D. Tuy nhin con ngi nhn bit

chuyn ng qua s thay i sng ca im nh. Do c nhng chuyn

ng m con ngi khng c cm nhn c nh l chuyn ng ca qu cu

ng mu. T ta c phng php pht hin chuyn ng u tin l so

snh skhc bit theo thi gian.

z

x

y

mt phng chiu

P1

P2O

Tm chiu



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14

b. Phng php so snh skhc bit

Chng ta xc nh sai khc Dk,k-1 gia frame th k v th k-1 nh

sau :

Dk,,k-1 = Fk Fk-1

trong : Fk l frame ti thi im k

Nu camera tnh, s thay i nh sng rt nh v nhiu khng ng

k th mt im c coi l chuyn ng nu khc bit ca n ln hn 0 v

ngc li sng yn.

Tuy nhin trong thc t cc iu kin trn kh c th xy ra. Do

loi b cc im m chng ta pht hin sai do nhiu gy ra, ta c th dng

mt ngng T thch hp.

Mk,k-1( x, y ) = >

laiNguoc

neu

0

T|)yx,1(-k,Dk,|1

Vi Mk,k+1c gi l mt n chuyn ng thi im k, nu bng

1 th im c coi l chuyn ng v bng 0 th im l ng yn. T

l ngng thch hp c th l mt gi tr c thc xc nh trong qu trnhthc nghim hoc da trn cc thut ton. c gi c th tham kho mt

thut ton xc nh ngng ph lc B ca [1].

frame th k frame th k-1

mt n chuyn ng

H7: Kt qu ca phng php so snh skhc bit



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u im ca phng php ny l n gin v d ci t do tc

s nhanh. Tuy nhin nhc im ca n l nhng vng tht s chuyn ng

nhng do ng mu nn sc hiu l ng yn v nhng vng tht sng

yn th li cho l chuyn ng.

khc phc nhc im trn ta c mt thut ton so snh khc

bit ci tin:

Bc 1: To mt cu trc Pyramid Gaussian trong mi frame

c c trng bi nhiu phn gii khc nhau. Bt u x lmc phn gii

thp nht.

Bc 2: Vi mi im mc phn gii hin ti, tnh ton khc

bit chun ha:

FDNk,r( x, y ) =

+

yx

yx

cryxf

ryxfryxfkyxf

,

2

,

,,(

,,(),,(),,(

trong :

N: l cc im trong ln cn ca x

),,( ryxf : l gradient ca mt nh ti im (x, y)

),,( kyxf : l frame thi im k

c: l hng s

Nu khc bit chun ha ny cao hn khc bit phn gii

trc th thay th khc bit trc bng khc bit mc hin ti. Nu

khng th vn gi nguyn gi tr trc .

Bc 3 : Lp li bc 2 cho tt c phn gii

Bc 4 : Ly ngng vi s khc bit chun ha mc phn gii

cao nht.



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c. Phng php trnn

Phng php trn cng da trn s so snh gia 2 nh, nhng

khng phi l 2 nh lin tip trong chui nh m l gia cc nh trong chui nh

vi mt nh tham chiu gi l nh nn. nh nn l cnh thu c khi khng c

i tng chuyn ng no ht. Gi B l nh nn thu c, ta c khc bit

gia nh nn v nh th k trong chui nh

Dk= Fk B

Nu nhiu t v khng c s thay i ca nh sng th im c ta

( x, y ) c xem l tnh nu Dk( x, y ) = 0 v ngc li. Tuy nhin trong thc

t lun c nhiu v vy ta phi dng ngng hn ch nhiu

1 Nu Dk( x, y ) > T

Mk( x, y ) =

0 ngc li

Vi Mk l mt n chuyn ng, im ( x, y ) c xem l chuyn

ng khi Mk( x, y ) = 1 v ng yn khi Mk( x, y ) = 0.

Trong thc tnh nn lun lun bin i do s thay i sng dogi, cc m my bay qua v th ta phi lun cp nhp nn li. Gi Bk l nn

thi im k. Ta c nn thi im k + 1 c cp nht nh sau:

*Bk( x, y ) + ( 1 - ) Fk( x, y ) nu Mk( x, y ) = 0

Bk+1( x, y ) =

Bk( x, y ) nu Mk( x, y ) = 1

Vi l mt hng sc gi l t l hc phn nh mc cp nht nn

nhanh hay chm.



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nh nn nh thk

bng ma mt n chuyn ng

H8 : bng ma trong phng php tr nn

Phng php tr nn cho kt qu tt hn phng php so snh skhc bit khi x l cc i tng ng mu, tuy nhin n c mt nhc im khi

nh nn cha mt i tng ng yn, sau i tng ny chuyn ng th

phng php trn s pht hin ra 2 i tng chuyn ng ch khng phi l 1.

i tng b pht hin sai ny c gi l bng ma. gii quyt vn trn

ngi ta phi s dng nh nn khng c i tng chuyn ng no trong ht

hoc c th da vo cc thut ton to nh nn.Ngoi ra cn mt hng tip cn mi trong phng php tr nn

l da trn m hnh xc sut thng k. tng chnh y l a ra mt m

hnh thng k cho nn. Thng c hai m hnh thng k chnh l n phng

thc ( unimodal ) v a phng thc ( multimodal ). Trong m hnh n phng

thc mi im c m hnh vi phn phi xc sut n thng l phn phi

Gaussian ( x, y, k, k ), trong k l gi tr trung bnh v k l ma trn hip

phng sai ca phn phi frame t. Nhng im m mu quan st c gn

( hay cn gi l khp ) vi phn phi nn th c phn thnh im nn hay l



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im ng yn v ngc li l im chuyn ng. V nn lun lun thay i nn

ta phi cp nhp li m hnh nn nh sau:

t+1 = ( 1 - )*t + *dt

t+1 = ( 1 - )*t + *dt*dtT

Vi l hng s ch mc iu chnh m hnh nn nhanh hay

chm.

i vi m hnh nn a phng thc ( multimodal ), chng ta cn

n nhiu phn phi xc sut c lp vi nhau m hnh mi im nh. Mi

phn phi c gn vi mt trng sc trng cho mc u tin ca chng.

Ch mt vi phn phi u tin vi trng s ln mi c dng m hnh cho

nn. Mt phn phi mi ca s quan st sc cp nhp vo m hnh nn nu

nh n khng khp bt c phn phi no c trng cho m hnh nn, ngc li

n trng s ca cc phn phi sc cp nhp li nh sau:

( 1 - ) wt+1,i + i = m

wt+1,i =

( 1 - )wt+1,i i m

Vi m l ch s ca phn phi khp vi phn phi mi ca s quan st,

c gi l t l hc trng s

d. Phng php da trn Optical Flow

y l mt phng php phc tp v i hi cc phn cng t tin

chy real-time nn chng ta ch ni khi qut v n.

Cc chuyn ng ca i tng trong 3D c gy ra chuyn ng2D trong mt phng nh c gi l Optical Flow. Optical Flow tng ng vi

s cm nhn chuyn ng ca mt ngi.



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H9: Hnh nh cc xe v Optical Flow ca chng

Optical Flow c ng dng nhiu trong nhn dng hot ng. Khi mi

vn ng c m hnh ha bng m hnh chuyn ng l t hp tuyn tnh ca

cc vn ng cbn. Cc vn ng cbn ny l cc Optical Flow c hc

trong qu trnh hun luyn.

2.3.5.2 c lng chuyn ng

Nh ni, thng tin v chuyn ng rt quan trng trong x l v

nn video. Nn nh l cc phng php nhm lm gim s bit cn thit c

trng video. Trong khi cc k thut x l video l cc phng php bin i

trn chui nh nh l nng cao cht lng chui nh. Vic phn lp nh trn c quan trng trong vic a ra ch ca vic c lng chuyn ng tc l lin

quan n vic chn m hnh x l sao cho ph hp. V d nh trong nn video

th cc tham s chuyn ng c c lng u dn n mt vic l t c

t l nn cao nht. Do cc chuyn ng c tnh ton khng cn phi ging

vi cc chuyn ng tht ca im nh min l ta t c mt t l bit ti thiu.

Tuy nhin, trong x l video th cc chuyn ng tht ca cc im nh li l

iu ta quan tm. pht trin mt thut ton c lng chuyn ng th theo

Janusz Konrad ta cn c 3 yu t sau: M hnh, tiu chun v chin thut tm

kim.



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20

a. Cc m hnh chuyn ng

C 2 m hnh cn thit trong c lng chuyn ng: m

hnh chuyn ng ( l cch c trng vn ng trong mt chui nh ) v m

hnh quan st ( l m hnh m c s lin quan ca cc tham s chuyn ng vi

mt nh ). Trong m hnh chuyn ng ta li c m hnh chuyn ng theo

khng gian v theo thi gian.

M hnh chuyn ng theo khng gian

Hu ht cc chuyn ng u l s kt hp ca php chiu

cc chuyn ng ca i tng trong cnh 3D v chuyn ng ca camera.

Trong khi chuyn ng ca camera nh hng n chuyn ng ca ton b hay

hu ht cc im nh th chuyn ng ca i tng chnh hng ti cc im

tng ng vi hnh chiu ca i tng. Trong lun vn ny chng ti nghin

cu trn camera tnh v th chng ti s khng nghin cu chuyn ng ca

camera. Ni chung chuyn ng ph thuc rt nhiu yu t nh l cc php

chiu, m hnh ca i tng 3D... Ta xt trng hp ng gin nht l chuynng tnh tin ca i tng 3D. Khi vector vn tc tc thi ca im x trong

mt phng nh s l

v(x) =

2

1

b

b

Trong cc tham s b = (b1, b2)T = (v1,v2)

T ph thuc vo

gc quay ca camera v cc tham s trong chuyn ng tnh tin 3D. M hnh

tnh tin 2D ny ng dng rt nhiu trong thc tc bit l trong nn video v

n a ra mt xp x gn ng vi hu ht nh trong t nhin. Khi chuyn ng



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ca vt th 3D c thm cc chuyn ng affine th ta c m hnh chuyn ng

affine vi 6 tham s

v(x) =

2

1

b

b

+ xbbbb

65

43

R rng m hnh chuyn ng tnh tin l trng hp c bit

ca m hnh chuyn ng affine. Hu ht cc m hnh chuyn ng phc tp u

a ra rt tt nhng ty vo tng ng dng. Khng phi lc no chng cng ci

thin c s chnh xc trong c lng chuyn ng. Ni chung, s tham s

cng nhiu th vic m t chuyn ng cng chnh xc hn.

M hnh chuyn ng theo thi gianQuo ca mt im nh ring bit c v trong khng

gian (x, y, t) ca mt chui nh c thc xem nh l ty bi v chng ph

thuc vo vn ng ca i tng. Trong trng hp n gin nht, quo

ca chng l tuyn tnh. Gi s chng ta c vn tc vt(x) gia thi gian t = tk-1 v

thi gian ( > t ) l mt hng s, mt quo tuyn tnh c thc trnh by

nh sau:x() = x(t) + vt(x)( - t ) = x(t) + dt,(x)

Trong dt,(x) = vt(x)( - t ) l mt vector dch chuyn c

o theo hng thi gian. Cho nn i vi chuyn ng tuyn tnh, nhim v ca

chng ta l tm 2 thnh phn ca vector vn tc v hay vector dch chuyn d ca

mi im x.

Mt s mrng trong t nhin ca m hnh quo tuyn

tnh l m hnh ng cong bc 2. Khi ta c thm mt i lng mi l gia

tc ca mt im.



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22

x() = x(t) + vt(x)( - t ) +2

1 at(x)( - t )2

Trong gia tc at l o hm ca vn tc vt. Cc m hnh

trn i hi 2 ( i vi tuyn tnh ) hoc 4 ( i vi bc 2 ) ti mi im x.

gim gnh nng tnh ton, m hnh tham s theo khng gian c th kt hp vi

cc m hnh trn.

Vng htr

Tp im x m trong cc m hnh khng gian v thi gian

p dng c gi l vng h tr. S la chn ca mt m hnh v vng h trl

mt trong cc yu t quyt nh n tnh chnh xc ca c lng cc tham schuyn ng. Thng thng khi cho mt m hnh chuyn ng, vng h tr

cng nh th vic xp x cng tt hn, bi v vi vng h trln th chuyn ng

c th phc tp v do ta phi c m hnh chuyn ng phc tp hn. Thng

thng vng h tr() c th thuc 1 trong 4 loi sau:

1. l ton bnh: Mt m hnh chuyn ng

c p dng cho ton bnh. M hnh ny

thch hp cho vic c lng chuyn ng

ca camera.

2. l mt im nh: M hnh ny p dng cho

mt im nh. Trong trng hp ny ta

thng s dng m hnh khng gian t nh tin

kt hp vi m hnh tuyn tnh hoc bc 2.

3. l mt khi im hnh ch nht: Cc m

hnh vn ng sc p dng trn mt khi

im nh hnh ch nht. Trong trng hp



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n gin nht, cc khi ny khng ph ln

nhau v hp ca chng s bao ph ton b

nh. Trong trng hp ny m hnh chuyn

ng khng gian tnh tin kt hp vi m

hnh chuyn ng thi gian tuyn tnh c

xem l m hnh hiu qu nht v c p

dng trong cc chun nn video nh l

MPEG-1, MPEG-2...

4. l mt vng bt k: Cc m hnh vn ng

s p dng trn cc im thuc vo . y

vng s tng ng vi cc i tng. K

thut ny c p dng trong chun nn

MPEG-4.

M hnh quan st

Khi chuyn ng c c lng ( v c quan st bng

mt ngi ) da trn s thay i ca cng sng, mu hoc c hai, cc miquan h ginh gia cc tham s chuyn ng v mt nh ng mt vai tr

rt quan trng. Gi thuyt hp l v thng thy l cng sng vn khng

i theo quo chuyn ng (i tng khng thay i sng khi di chuyn).

i vi cc nh c ly mu theo thi gian iu ny c ngha l

Ik(x(tk)) = Ik-1(x(tk-1))

S dng cng thc trong m hnh chuyn ng theo thi gian vi t = tk-1, = tkv gi thuyt rng chng ta ly mu nh theo khng gian, ta c:

Ik(n) = Ik-1(n-d).



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Tuy nhin chng ta khng th s dng cng thc trn tm d trong thc t v

nhiu q. Cng thc trn c vit li nh sau:

Ik(n) = Ik-1(n-d) + q(n)

Do d c tnh bng cch ti thiu hm li gia Ik(n) v Ik-1(n-d).

b. Tiu chun c lng

C rt nhiu tiu chun c lng ty thuc vo yu cu ca bi

ton. Trong nn nh th li don ca bc lng l rt quan trng. Cn

trong php ni suy b p chuyn ng th li ni suy cc i li l mi quan

tm. Ngoi ra ty thuc vo kh nng x l m vic c lng chuyn ng thc

hin trn . Ni chung cc tiu chun c lng u c mc ch chung l cc

tiu ha hm li:

k(n) = Ik(n) k(n) n

Trong k(n) = Ik-1(n d(n) ) c gi l c lng b p chuyn ng ca

Ik(n).

c. Chin thut tm kim

Mt khi m hnh chuyn ng c xc nh v kt hp vimt tiu chun c lng, bc cui cng l pht trin mt chin lc hiu qu

c v tnh phc tp v cht lng li gii c lng cc tham s chuyn ng.

i vi mt s t cc tham s vn ng yu cu khng gian trng thi nh th

chin lc thng dng nht khi ti thiu hm li l so khp. Trong hng ny,

cc c lng b p chuyn ng Ik-1( n d(n) ) cho cc ng vin chuyn ng

d c so snh vi nh gc Ik(n) trong vng h trca m hnh vn ng. ng

vin no khp nht i vi tiu chun a sc chn c lng. Ngoi

ra ta cn c nhiu phng php c lng na m chng ta s khng ni ti: k

thut da trn gradient, thut ton tin cy cao nht c chn u tin...



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25

CHNG 3

THEO VT V PHN LOI I TNG

Trong chng ny chng ta s p dng cc thut ton x l video

c nghin cu phn trn vo bi ton theo vt v phn loi

i tng.



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3.1 Bi ton theo vt v phn loi i tng

Vic theo vt v phn loi i tng ang c nghin cu trong nhngnm gn y. Trong ng dng theo vt v phn loi i tng chng ta phi

phn loi c i tng v ch theo vt i tng chng ta quan tm. Theo vt

i tng l chng ta lu li c ng i ca cc i tng ang vo vng

quan st ca camera. Ta c thng dng vo cc h quan st gim c chi

ph lu tr cc d liu thc t cc camera quan st. Hnh nh t camera

truyn vo my tnh, sau my tnh x l. Nu trong c cc i tng m

chng ta quan tm th my tnh s lu on phim ny li sau ny chng ta x

l. Nh cp trong chng I, kch thc ca d liu video l rt ln v th

vic lu tr c chn lc ny s gim c chi ph cho vic lu tr rt nhiu.

Trong bi ton ny chng ti s theo vt nhng i tng no l ngi. Thng

thng khi theo vt i tng ngi ta thng dng 4 phng php sau:

Phng php 1: Theo vt i tng da theo cc c im ring ca i

tng. Phng php ny cho kt qu kh tt v c th p dng c i vi

camera ng nhng i hi chng ta phi c tri thc vi tng cn theo di,

tc l chng ta phi c c cc danh sch cc c im ring ca i tng.

Phng php 2: Phng php ny s dng phn b mu ca i tng

theo vt. Tiu biu ca phng php ny l MeanShift v CamShift. Phng

php ny thng c ng dng trong tracking ngi da vo s phn b mu

da.Phng php 3: Phng php ny xem cc i tng chuyn ng nh l

cc vng lin thng v theo vt cc i tng bng cch so khp cc vng lin

thng tm vng khp nht.



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27

Phng php 4: Phng php ny theo vt i tng da vo ng bin

ca chng. Phng php ny tng t vi phng php 3 v chng ta theo vt

bng cch cp nhp ng bin ca i tng.

3.2 M hnh xl bi ton

Trong bi ton trn, d liu m chng ti x l s l on video c quay

t camera v ghi li vi chun AVI. M hnh x l bi ton c thc trnh by

nh sau:

D liu thu c t camera c t cnh sc truyn vo my tnh.

D liu ny qua mt b tin x l lc nhiu.... Sau n s qua b pht hin

chuyn ng. B pht hin chuyn ng s pht hin im no l im tnh (

im nn ) v im no l chuyn ng. T ta dng php phn tch connected

component rt trch cc i tng chuyn ng v truyn danh sch cc i

tng rt trch c qua bc lng chuyn ng. Bc lng chuyn ng

sc lng chuyn ng ca cc i tng c trong danh sch i tng v so

khp vi cc i tng mi . Ty vo cc trng hp m ta s cp nhp li v tr

ca i tng, loi bi tng ra khi danh sch i tng hay l thm mt itng vo danh sch i tng. Sau cc i tng ny sc chuyn qua b

phn loi chn lc cc i tng l ngi v theo vt Vic theo vt l lu li

v tr ca cc i tng ang trong vng quan st v cui cng ta sc qu

o chuyn ng ca i tng. Trong phn ny biu din vic theo vt i

tng chng ti s v khung bao quanh i tng. Sau y l s tm tc qu

trnh theo vt v phn loi i tng ca chng ti.



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H10: S x l bi ton

3.3 Tin xl

D liu t my camera lu vo my tnh di dng file AVI. Trong chun

file ny h mu m n dng l RGB vi phn b mu l BGR. Sau khi kho st

cc h mu RGB, HSV, YUV chng ti chn thnh phn Y ca h mu YUV.

Do cc frame nh t file AVI phi c chuyn sang h mu YUV v ly

thnh phn Y x l. Sau frame nh ny s qua b lc lc nhiu. B lc

thng dng l Median v Gaussian. Vi cc b lc ny chng ta s gim bt

cc chuyn ng khng cn thit nh l cc chuyn ng ca l cy...

3.4 Pht hin chuyn ng b pht hin chuyn ng, u vo l nh qua b tin x l, v v th

chng ta ch s dng thnh phn Y x l. y l bc cbn nhng cng l

bc quan trng nht. Nu ta x l khng tt bc ny th kt qucc bc sau

s khng cao. trong phn ny d liu vo l cc frame ca on video thu

c t camera tnh qua giai on tin x l, v chng ta s tch cc i tng

chuyn ng. Cc i tng chuyn ng c hnh dng, mu sc khc nhaunhng c cng chung c im l chuyn ng. li dng tnh cht trng lp

thng tin gia cc frame nn phng php ch yu trong phn ny l trnh.

Nh trnh by trong chng I, hai phng php c s dng ch yu trong

Tin x l Pht hin chuyn ngcapture

Theo vt i tngPhn loi itng



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pht hin chuyn ng l so snh s khc bit v tr nn. Nhc im ca

phng php tr nn l nhy cm vi nn v nhc im ca phng php so

snh s khc bit l khng pht hin c chuyn ng ca phn bn trong cc

i tng ng mu. [3] ra mt phng php rt hay, l kt hp gia 2

phng php trn. Trong khi phng php so snh s khc bit ca 3 frame lin

tip c thc hin xc nh cc vng chuyn ng hp l th phng php

tr nn c thc hin tip sau s lp y cc phn cn li m phng php

so snh s khc bit khng pht hin ra. Xem xt chui nh c truyn vo

t camera tnh. Gi In(x) t trng cng ti v tr x v thi gian t = n.

Nguyn l trong so snh 3 frame khc bit l : Mt im c coi l chuyn

ng nu cng ca n thay i ng k gia frame hin ti v frame trc

n , gia frame hin ti v frame trc na. Tc l im x l chuyn ng

nu:

( | In(x) In-1(x) | > Tn(x) ) v ( | In(x) In-2(x) | > Tn(x) ).

Trong Tn(x) l ngng m t s thay i cng ng kv tr x. Vn

chnh ca phng php so snh s khc bit l nhng im nm bn trong itng ng mu th khng nm trong tp cc im chuyn ng. Tuy nhin, sau

khi phn cc im chuyn ng thnh cc vng chuyn ng th cc im nm

bn trong c thc lp y bng cch p dng phng php tr nn ly ra tt

c cc im chuyn ng nm bn trong hp R bao quang vng chuyn ng.

Gi Bn(x) c trng cho cng nn hin ti im x. Vng bn c thc

lp y bng cc im nm trong R m c cng khc bit ng k so vi

nn.

bn = { x: | In(x) Bn(x) | > Tn(x), x R }



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Tuy nhin phng php ny c mt nhc im l phn kt qu cui cng

bao gicng ph thuc vo lng thng tin m phng php tr nn c c.

Khi p dng phng php ny vo theo vt i tng l ngi s gp mt kh

khn l phng php tr nn s cho ra kt qu khng tt thng l c s ngn

cch gia u ngi v thn ngi v v th s cho ra hai i tng ch khng

phi l mt i tng. Mc khc khi chng ti p dng phng php trn th gp

mt li nh m chng ti nghl do b th vin OpenCV gy ra. Khi s dng b

th vin OpenCV captrure on video v ly tng frame nh ra, th c sau 5

frame chng ta li c mt frame trng vi frame trc. Do phng php so

snh 3 frame lin tip s cho kt qu sai. Cui cng chng ti chn phng

php tr nn. Phng php ny nhy cm vi nn v cho kt qu khng tt lm

v th chng ti s dng cc b lc tuyn tnh v b lc morphology kh

nhiu v lp y khong trng gia u ngi v thn ngi.

Gi B(x) l nh nn, I(x) l nh hin ti, D(x) l khc bit gia nh nn

v nh hin ti

D(x) = | B(x) I(x) |Khi ta c mt n chuyn ng l

0 nu D(x) < T(x)

M(x) =

1 ngc li

Trong T(x) l ma trn ngng ch sai khc ng k gia nh hin ti

v nh nn. C hai nh nn Bn v ngng Tnu l thuc tnh thng k

ca cng im nh c quan st t chui nh Ik (k < n ). B0(x) l nh

u tin trong chui nh, B0(x) = I0(x) v T0(x) c cho mt gi tr mt



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nh khc khng. B(x) v T(x) c cp nhp theo thi gian theo cng

thc sau.

Bn(x) + ( 1 - )In(x) nu x ng yn

Bn+1(x) =

Bn(x) nu x ng

Tn(x) + ( 1 - )(5*|In(x) Bn(x)|) nu x ng yn

Tn+1(x) =

Tn(x) nu x ng

Trong l gi tr ch mc p ng ca nn i vi s thay i ca

mi trng. c th l 1 hng sc chn theo kinh nghim hoc c thc

cp nht nh sau: Gi Q l tp hp cc im c chn ngu nhin v khng

thuc vo phn chuyn ng frame trc. Chng ta tnh ton mt t s thay i

sng (t) tng ng vi cc im trong Q.

(t)=

Qq qB

qI

)(

)(1

Vi I(q) l cng ca im q ti frame hin ti, v B(q) l cng

ca im q ti nh nn.

Trong trng hp t s thay i sng ny ln hn ngng cho trc th

chng ta siu chnh li tham s cp nhp nn nh sau:

= 0.01 +c

t)( nu (t) >

Vi c l mt hng s cho trc, c c xc nh bng thc nghim.

Sau y l s ton b qu trnh trong b pht hin chuyn ng.



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H11 : S x l trong b pht hin chuyn ng

By gichng ta si chi tit mt s thut gii trong s trn. l

thut gii tr nn, thut gii cp nhp nn, thut gii cp nhp ngng v

thut gii rt trch i tng chuyn ng.

a. Thut gii tr nn

input: nh nn B, nh hin ti I v ma trn ngng T

output: nh M l mt n chuyn ng

Ngng

Tr nn

Rt trch i tngchuyn ng

Cp nhtngng

Cpnht nn

frame knh nn



39/80

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m := getHeight(M);

n := ge tWid th(M);

for x := 1 to m dofor y := 1 to n do

if | B[x,y] I[x,y] | > T[x,y] then

M[x,y] := 255;

else

M[x,y] := 0;

y chng ti s dng nh xm lm mt n chuyn ng thayv dng nh nh phn do M[x,y] s nhn mt trong hai gi tr l 255 ch

mu trng( im chuyn ng ) v 0 ch mu en ( im ng yn )

b. Thut gii cp nht nn

input: nn B, nh hin ti I v mt n chuyn ng M

output: nn B c cp nht li

m := getHeight(B);

n := getWid th(B);

for x := 1 to m do

for y := 1 to n do

if M[x,y] = 0 then

B[x,y] := *B[x,y] + ( 1 - )*B[x,y];

c. Th tc cp nht ngng

input: ma trn ngng T, nn B, nh hin ti I, mt n chuyn ng M

output: ma trn ngng c cp nht.



40/80


41/80

35

Med ian( M, temp );

Close( temp , M );

L := getConnec tedCom ponent( M ); Thut gii trch ly i tng chuyn ng

Input: L danh sch cc thnh phn lin thng

Output: A danh sch cc i tng chuyn ng

j := 1;

For i:= 1 to getSize(L) do

If getObjec tSize( L[i] ) > c then

Begin

Initia lOb jec t( A[ j], L[i] );

j := j +1;

End

Sau y chng ta xem kt qu thc hin ca gii thut rt trch cc

i tng chuyn ng.

frame hin ti



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Mt n chuyn ng khi dng phng php tr

nn. Vn cn nhiu v c s phn cch nh giaxe my, thn mnh v u

Mt n chuyn ng khi ci tin phng php tr

nn. Cc phn nhiu c lc b v cc phn

xe my, thn mnh v u c lin kt vi

nhau

Khi th nghim phng php pht hin chuyn ng trn chng ti thu

c kt qu sau:

Tng s frame th nghim l 2010



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Thi gian x l l 145 giy

Tc x l trung bnh l 13.6 giy

Cc i tng chuyn ng u c pht hin

3.5 Theo vt i tng

Sau khi cc i tng c pht hin, chng ta s tin hnh theo vt

i tng. Hu ht cc h thng hin nay u theo vt i tng da vo b lc

Kalman. y chng ti cng s dng b lc Kalman nhng c mt s sa i.

Nh bit theo vt i tng c ngha l chng ta phi phn tch v ghi li qu

o ca i tng. c th theo vt tt chng ta phi c lng c chuyn

ng ca i tng. Mi i tng sc c trng bi mt s tham s sau:

1. p = V tr trong ta nh. Ta ca trng tm ca i tng

s chnh l ta ca i tng.

2. p = l khng chc chn ca v tr. Khng bao gichng ta

c thc lng chnh xc c v th khng chc chn ny

chnh l sai s trong c lng.

3.>v = tc ca i tng. y chng ta s dng dch

chuyn thay cho tc v chng ta ang xt l cc im ri rc

ch khng phi l cc im lin tc.

4. >

v = khng chc chn ca vn tc.

5. = hnh ch nht bao quanh i tng.

6. d : l mt s ch tin cy ca i tng. tin cy ny s dng

quyt nh loi b hay theo vt i tng.



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3.5.1 Don v tr ca i tng trong tng lai

Vic c lng v tr ca i tng trong mi frame l rt quan

trng. N gip cho vic tnh ton n gin hn v vic theo vt s chnh xc hn.

V trc lng sc s dng la chn s cc i tng cn phi xem xt

trong qu trnh theo vt. Vic c lng s gim c rt nhiu thi gian v vi

mi i tng chng ta khng cn phi xem xt trn ton bnh m ch xt

trong vng c don m thi. Gi t l thi gian gia 2 frame, theo m hnh

chuyn ng tuyn tnh th ta c

pn+1 = pn + v*t

V khng chc chn c cho l bng khng chc chn ca v tr hin ti

cng vi khng chc chc ca vn tc nhn cho thi gian.

pn+1 = pn + vn*t

Nhng v tr ny sc chn c lng v tr mi ca i tng trong frame

tip theo. Mi i tng trong frame hin ti sc don v tr mi bng

cch cng hnh ch nht bao quanh i tng mt khong l vn*t sau m

rng ra mt khong pn+1. Do d nu c vng chuyn ng mi no thuc vovng don ny th ta s tin hnh so khp.

3.5.2 So khp i tng

Cho mt vng i frame hin ti, chng ta tm vng khp vi

vng ny frame tip theo bng phng php so khp tng quan nh. Hm

tng quan gia vng frame hin ti vi vng ng vin frame tip theo v

cch vng ny mt khong d l:

C(d) =

++

Rx

nn

W

dxxjiW II )()(),( 1



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Trong : In l mt im nh ti frame hin ti, In+1 l mt im nh ti

frame tip theo. W l hm trng s v ||W|| c tnh bng cng thc sau:

= Rx xWW )( y W(x) l hm trng s th hin mc u tin ca im x. Cc i tng

m chng ta quan st c c th di chuyn t xa ti hoc i ra xa. Khi kch

thc ca chng frame tip theo s ln hn hoc nh hn. V th hm trng s

ny phi c tnh lm sao cc im gn tm ca i tng s c u tin

cao hn. V gim chi ph tnh ton th hm trng s ny ch p dng i vi

cc im nh no c xem l chuyn ng, do cc im c xem l ng

yn s c hm trng s bng 0. Nu x l im chuyn ng ta c:

+=

r

xrxW

max

)(1

2

1

2

1)(

Trong r(x) l khong cch bn knh t x ti tm ca vng , v rmax l khong

cch bn knh ln nht trong . gim chi ph tnh ton ta c thc lng

tm ca i tng chnh l tm ca hnh ch nht bao quanh i tng v

khong cch ln nht trong vng bng mt na ng cho ca hnh ch nht

bao quanh i tng. Khi so khp vng i tng c kch thc m*n th chi ph

tnh ton s l O(m2n2). Nu kch thc ca vng i tng ln th chi ph s

tng ln rt ln kh m kim sot c. V th chng ti cnh mt ngng

m chi tnh ton s khng vt qua ngng . y chng ti chn ngng l

25 im nh. Kch thc ca vng nh theo mi chiu s b gim i mt na nu

n ln hn 25 v chng ti sm s ln gim kch thc la chn cc im

khi so khp. V d nh mt vng c kch thc 80*45 th kch thc s gim i



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2 ln theo chiu x v 1ln theo chiu y. Do trong qu trnh so khp, theo

chiu x c 4 im th s chn mt im so khp v c 2 im theo chiu y th

s chn 1 im. Vi cch x l nh trn th phc tp ca thut ton khng bao

giqu O(254). Sau y l thut gii so khp i tng

Input: i tng frame hin ti currentObject, i tng frame tip

theo targetObject, 2 frame nh In v In+1.

Ouput: C(d)

x1 := c urrentOb jec t.ob jec tRec t.x;

y1 := currentOb jec t.ob jec tRec t.y;

x2 := c urrentOb jec t.ob jec tRec t.x +

currentObject.objectRect.width;

y2 := currentOb jec t.ob jec tRec t.y +

currentObject.objectRect.height;

xStep := 1;

yStep := 1;

while( m > 25 )

yStep := yStep + 1;

while( n > 25 )

xStep := xStep + 1;

Cd := 0;

for y := y1 to y2 do

for x := x1 to x2 do

begin

if M[x,y] > 0 then



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begin

Wx := ( )rrx

max

1

2

1

2

1+ ;

Cd := Cd + ],[].[* 1 dyydxxyxWx II nn +++ + ;

end

x := x + xStep ;

y := y + yStep;

end

3.5.3 Theo vt i tng

Theo vt i tng th rng ln hn l so khp i tng. Chng ta

phi lu vt c quo chuyn ng ca i tng. chnh y l so

khp i tng c c vi cc i tng m ta thu c frame tip

theo. Cc i tng frame tip theo sau khi qua b pht hiu chuyn

ng s rt trch ra c cc vng chuyn ng. Chng ta s to mt

danh sch cc vng chuyn ng thun tin cho vic theo vt. Sau chng ta c lng v tr mi ca cc i tng frame hin ti. Khi

vic so khp s d dng hn. Chng ta ch so khp cc i tng vi vng

chuyn ng mi m v trc lng ca cc i tng ny thuc vo

vng chuyn ng mi . Ty trng hp so khp m chng ta c cc

quyt nh theo vt khc nhau. Sau y l s thut gii theo vt i

tng.



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H12: S theo vt i tng

N

Y

Rt trch cc vngchuyn ng

Don v tr mi cacc i tng A

Duyt A tm cc

i tng j khp vivng chuyn ng i

i = 1

i Bi

Stop

Tm i tng trongkhp vi i i = i + 1

Cc i tngang lu tr

Frame j

Danh sch cc

vng Bi



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Khi so khp cc i tng trong j vi i tng i s xy ra cc trng hp

sau:

1. Khng c i tng no khp vi vng chuyn ng ht. y

ta c 2 trng hp xy ra: mt l vng chuyn ng ny mi vo

vng quan st. Khi ta to mt i tng mi thit lp cc

tham s ban u nh l v tr, vn tc , .... v cho tin cy

mc thp nht. Trng hp hai l ta don sai. Khi ny ta c

th mrng vng tm kim v so khp cc i tng.

2. Ch c mt i tng khp vi vng chuyn ng. y l trng

hp tt nht trong theo vt. Lc ny ta s cp nht i tng theo

vng chuyn ng mi ny.

3. Mt i tng khp vi nhiu vng chuyn ng. iu ny c

th do i tng tch ra thnh nhiu i tng. y ta s cp

nht i tng hin ti theo i tng khp nht. Cc i tng

cn li s tng ng vi i tng mi v chng ta thit lp cc

tham s ban u cho cc i tng.4. Trng hp nhiu i tng cng khp vi mt vng chuyn

ng. Trng hp ny l do cc i tng giao nhau. y

chng ti ch xt 2 i tng giao nhau thi. Khi 2 i tng

giao nhau chng ti s xt v tr ca 2 i tng ny vi v tr

ca i tng m cp nht li v tr mi ca cc i tng. y

mi i tng sc c mt hnh ch nht bao quanh i

tng. Chng ti s so snh gc tri trn v gc phi di ca

cc hnh ch nht bao quanh i tng a ra cc quyt nh



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cp nht li v tr hnh ch nht bao ny theo gc tri trn hay

gc phi di ca vng mi. V d

Frame In Frame In+1

H13: v d thut ton so cp nhp v tr khi 2 i tng giao nhau

v d trn ta thy x21 < x11 do x21 = x1 cn x12 > x22 nn

x12 = x2, do dch chuyn theo phng x ca i tng 1 l

x1 = x2 x12 cn ca i tng 2 l x2 = x1 x12. Thnh phn

theo phng y c tnh tng t.

5. Trng hp cc i tng khng khp vi vng chuyn ng

no ht. Trng hp ny c th do i tng ra khi vng quan

st hoc l i tng ny bi tng khc che khut, v th

trong trng hp ny tin cy ca i tng s gim xung.

Khi tin cy gim xung di ngng cho php th ta s loi

bi tng ny ra khi danh sch.



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3.5.4 Cp nht i tng

Cc tham s ca i tng sc cp nht theo cc tham s ca

i tng mi. Gi d l dch chuyn ca i tng gia 2 frame In v frame

In+1. ta c

d =t

ppnn

+1

Vi pn+1 l v tr mi ca i tng.

Khi ta c vn tc ca i tng c cp nhp nh sau:

( )

vv nnd *1*

1

+=+

v khng chc chn ca vn tc c cp nhp nh sau:

( ) vvv nnn d *1* 11 += ++

3.6 Phn loi i tng

Phn loi i tng l mt cng vic rt kh v tn rt nhiu thi gian.

phn loi i tng chng ta cn phi bit cc c trng ring ca i tng.

l cc c trng ring ca i tng m i tng khc khng c. C rt nhiu

phng php tm c trng v phn loi i tng, tuy nhin c hai phng

php chung, ph bin thng c s dng l:

1. Sdng Heuristics. Phng php ny a ra cc c trng ca i

tng m t kinh nghim hoc cc phn tch l thuyt vi tng

. Tc l ta da vo cu trc, hnh dng, mu sc ca i tng ...

Phng php ny c u im l cho kt qu tt v nhanh, tuy nhinn da vo trc gic ca con ngi nn nhiu lc kt qu li khng

tt lm, v c nhiu bi ton khi s dng phng php ny s lm

phc tp thm.



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2. Phng php thng k. Phng php ny tm cc c trng ca i

tng da trn kt qu quan st c ca mt tp mu. T kt qu

quan st ny chng ta s rt ra c cc c im chung, cc quy

lut chung ca tp mu. Phng php ny thng cho kt qu kh

tt v chng da trn cc quan st thc t. Tuy nhin phng php

c nhc im l i hi tp mu quan st phi ln v cng vic thu

thp tp mu rt kh khn v tn thi gian. Nu chng ta thu thp d

liu cho tp mu khng tt th kt qu s khng tt. Mt trng hp

in hnh ca phng php ny l mng neuron. Hin nay vi s

pht trin ca tc my tnh ngy cng nhanh th phng php ny

ang c s dng rng ri.

y v thi gian c hn v khng c iu kin thc hin phng

php thng k cho nn chng ti chn phng php Heuristics. y

chng ti s phn loi ngi i b vi cc i tng khc nh l xe, ngi

i xe my ... Vic phn loi ny da vo hnh ch nht bao i tng. i

vi ngi i b th chiu rng ca hnh ch nht rt ngn cn chiu cao thdi hn cn i vi cc phng i tng khc v d nh xe t th chiu

rng thng di hn chiu di. V th chng ti chn t l gia chiu rng

vo chiu di lm mt c trng phn loi.



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47

ta c:

nu

3

3)30( 0 =< tg

height

widthth i tng c xem l ngi

chuyn ng. Trong width l chiu rng ca khung bao i tng cn height

l chiu cao. Thuc tnh hnh ch nht bao quanh i tng cha s dng n

hnh dng ca i tng do ta c mt hng khc phn loi i tng.

width

Np =

p T i tng chuyn ng l ngip < T i tng chuyn ng khng phi l ngi

Trong N l sim chuyn ng trong hnh bao i tng, width l

chiu rng ca ng bao.



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CHNG 4

CI T CHNG TRNH



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4.1 Mi trng ci t

Chng ti ci t th nghim chng trnh bng ngn ng C++ v trin

khai trn mi trng Window bng b cng c Visual Studio 6.0. Chng ti s

dng thm th vin Intel OpenCV h trx l. y l mt th vin m ngun

mca Intel v x l th gic my tnh.

4.2 Cu trc chng trnh

4.2.1 Cu trc dliu

Ngoi cc d liu cbn trong C++ chng ti cn s dng cc cu

trc ca th vin Intel OpenCV nh l IplImage lu tr cu trc nh. Cu trc

ny tha k t th vin IPL( Intel Image Processing Library ). Do cu trc ny

kh phc tp nn chng ti khng trnh by trong lun vn ny. Chi tit cc bn

c th xem trong ti liu ca th vin Intel OpenCV

m t mt i tng chuyn ng chng ti xy dng cu trc

MovingObject

typedef struct tagMovingObject

{

int objectConfidence;

CvRect objectRect;

CvPoint2D32f objectVelocity;

CvPoint objectCentroid;

CvPoint2D32f objectVelocityUncertainty;

CvPoint2D32f objectPositionUncertainty;

CArray< int , int > arrTargetObjectIndex;

BOOL objectUpdated;

}MovingObject, *pMovingObject;



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Trong cu trc MovingObject trn ta c mt vi cu trc khc :

typedef struct CvPoint

{

int x; /* x-coordinate, usually zero-based */

int y; /* y-coordinate, usually zero-based */

}

CvPoint;

typedef struct CvPoint2D32f

{

float x; /* x-coordinate, usually zero-based */

float y; /* y-coordinate, usually zero-based */

}

CvPoint2D32f;

typedef struct CvRect

{

int x; /* x-coordinate of the left-most rectangle corner[s] */

int y; /* y-coordinate of the top-most or bottom-most

rectangle corner[s] */

int width; /* width of the rectangle */

int height; /* height of the rectangle */

}

CvRect;



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4.2.2 Cu trc chng trnh

Chng trnh c xy dng da trn hai phn: phn giao din v

phn x l.

Trong phn giao din chng ti c s dng mt s lp v giao din

nh l CXPStyleButtonST, CbuttonST...

Trong phn x l chng ti xy dng mt lp x l video

CSequenceProcessing . Mt vi hm x l cbn trong lp ny nh sau:

/ / H m ly d liu t file AVI

void GetFile( const char* szFileName );

/ / H m khi to cc gi t r cn t h it

int Proces s AVI();

/ / H m t rnn r t r a i tng chu yn n g

void Ba ckgroun dSu btra ct ion( IplIm age *ba ckgroun dImage,

IplImage *currentImage,

IplIm a ge *foregrou n dIma ge,

IplIm a ge *th resh oldIma ge );

/ / H m thc h in cc cng vic x l

void Next ();

/ / H m s o khp i tn g

dou ble Mat ch ingObject( Movin gObject* cu rren tObject,

MovingOb ject* ta rgetOb ject);



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CHNG 5

KT QU V HNG PHT TRIN



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5.1 Kt qut c

5.1.1 Dliu thnghim

D liu m chng ti th nghim c quay trn mt con ng

gn cng vin Gia nh vo lc 5h chiu. D liu dc lu vo my qua cng

IEEE 1394 v dng phn mm Unlead Video Studio DV 5.0 x l v lu di

dng file AVI. y tit kim b nhchng ti lu di dng AVI nn. Cc

thng s nh sau:

Chun nn l Cinepak Codec.

Kch thc ca file AVI l 56,7Mb

Thi gian ca on film l 10 pht 07 giy

T l frame 30frame/giy

Chiu rng ca tng frame l 320 pixel

Chiu cao ca tng frame l 240 pixel

5.1.2 Kt qut c

Vi d liu trn chng ti tch c cc i tng chuyn ng.

X lc cc chuyn ng khng cn thit nh l chuyn ng ca l cy, cc

i tng chuyn ng c kch thc nhc loi b. Tuy nhin khi khung

cnh c qu nhiu i tng chuyn ng th thut ton cho kt qu khng tt

lm. Vic theo vt i tng kh tt, tuy nhin khi hai i tng gp nhau th

vic theo vt gp kh khn. V phn loi i tng cc i tng l ngi th

c nhn dng rt tt, tuy nhin v thut ton phn loi cn rt th nn khi cc

i tng khc khng phi l i tng ngi chuyn ng, chuyn ng phaxa camera th h thng nhn dng sai v cho rng l i tng ngi.



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5.2 Hng pht trin

Vi kt qut c hin ti, chng ti ra hng pht trin trong tng

lao:

1. H thng pht hin chuyn ng hin ti vn cn yu v chng da

trn thut ton tr nn rt nhy cm vi nhiu v s thay i ca

nn. Mc khc thut ton ny ch p dng vi camera tnh thi. Do

chng ti s pht trin mt h thng mi tt hn da trn cc m

hnh ton hc mi.

2. Xy dng mt h thng phn loi nhiu i tng. C th da trn

m hnh thng k c th l mng nron phn loi i tng.

3. T h thng phn loi ny ta c th xy dng cc h thng chng

trm bng cch a ra cc c trng ring h thng nhn dng

trm v a ra bo ng.



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TI LIU THAM KHO

[1] A.M.Tekalp , Digital Video Processing , Prentice Hall , 1995

[2] Hand Book of Image & Video Processing, Academic Press, pp.207-226 ,

2000

[3]Robert T.Collins , Alan J.Lipton and Takeo Kamade , A System for

VideoSurveillance and Monitoring , 1999

[4] LIU Ya, AI Haizou, XU Guangyou, Moving Object Detection and

Tracking Based on Background Subtraction, 2001.

[5] Fatih Poriki and Oncel Tuzel, Mitsubishi Research Laboratory, Human

Body Tracking by Adaptive Background Models and Mean-Shift Analysis,

7-2003

[6] Mathew Price, Video Classification and Tracking with Colour

Technical Report, 14-11-2002



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PH LC 1

MT VI HNH NH V KT QUT

C

1. Mt vi mt n chuyn ng



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60

Sau y l mt s frame m c i tng l ngi i b



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68/80

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2. Kt qu theo vt i tng



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3. Kt qu theo vt i tng l ngi



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69

PH LC 2

VI NT V THVIN INTEL OPENCV

1. OpenCV l g?

OpenCV l vit tt ca Intel Open Source Computer Vision. l mt

th vin gm nhiu hm C v mt s lp C++ da trn cc thut ton ph bin

trong x lnh v th gic my tnh.

OpenCV l mt th vin m ngn mv min ph.

OpenCV l mt nn tng giao din lp trnh t cp trung ti cao. N chn 300 hm C cho php x l tng im nh cng nh ton bnh hay on

video. Khi kt hp vi th vin IPP (Intel Intergrated Performance Primitives)

trn cc CPU Intel s ti u ha x l nhvn dng kin trc ca CPU. y l

mt th vin c th s dng c trn Window v Linux.

2. Cc chc nng ca thvin OpenCV

2.1 Cc kiu dliu cbn

OpenCV cung cp rt nhiu kiu d liu c cu trc nhm h trti a

vic x l. Cc kiu d liu c thc chia ra lm 2 loi:



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Cc kiu d liu gip : y l cc kiu d liu gip cho thao

tc vi cc d liu nh d dng hn nh l :

o IplImage: dng lu cu trc file nh

o CvPoint: dng lu v tr ca im nh

o CvRect:

o CvBox

o V nhiu kiu d liu khc

Cc kiu d liu ng: y l cc kiu d liu c OpenCV

pht trin gip vic x lc ti u:

o CvMemStorage: y l mt cu trc d liu cp thp

dng lu tr cc cu trc d liu tng ng nh l

sequences, graphs...

typedef struct CvMemStorage

{

struct CvMemBlock* bottom;/* first allocated

block */

struct CvMemBlock* top; /* the current memory

block - top of the stack */

struct CvMemStorage* parent; /* borrows new

blocks from */

int block_size; /* block size */

int free_space; /* free space in the top

block (in bytes) */

} CvMemStorage;

o CvSeq : y l cu trc nn tng ca tt c cu trc ng

c s dng trong OpenCV. OpenCV cng cho php

chng ta to cc cu trc d liu mi t cu trc ny.

o CvSet : y l cu trc k tha t cu trc CvSeq.

o CvGraph : Cu trc ny li k tha t cu trc CvSet.



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V cn nhiu kiu d liu khc na. bit thm chi tit c gi hy

tham kho trong file help ca OpenCV.

2.2 Cc hm xl trong OpenCV

V cc hm x l trong OpenCV ta c th chia ra nh sau:

2.2.1 Cc hm x l cc kiu d liu cbn

y l cc hm h tr cho vic x l cc cu trc d liu

trong OpenCV bao gm:

Khi to:

cvCreateImage : hm khi to mt cu trc IplImage

cvMat: hm khi to mt cu trc CvMat

cvCreateMemStorage: hm khi to mt cu trc

CvMemStorage.

CvCreateSeq: hm khi to cu trc CvSeq.

.......

Cc hm hy

cvReleaseImage: gii phng b nh ginh cho cu trcIplImage c cp pht bng hm cvCreateImage.

cvReleaseMat: gii phng b nhginh cho cu trc CvMat

c khi to bng hm cvMat.

cvReleaseMemStorage: gii phng b nhginh cho cu trc

CvMemStorage c khi to bng hm

cvCreateMemStorage.

.....

Ni chung cc cu trc c khi to t hm cvCreateXXX

th sc gii phng bng hm cvReleaseXXX



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Ngoi ra cn cc hm sao chp, ly thng tin t cc phn t trong

bn trong cu trc v cc ton t trn cc cu trc.

2.2.2 Cc hm v x lnh

Cc hm x lnh c thc phn thnh cc loi sau:

Cc hm vn gin: y cc hm thc hin cc thao tc v

n gin trn nh nh l v elip, hnh ch nht.... hay l vit

ch trn nh.

Cc hm v tm cnh v gc trong nh: cc hm ny s dng

cc thut ton thng dng trong tm cnh nh l cc mt n

Sobel, Laplace, Candy.....

Cc hm v ly mu, ni suy, bin i hnh hc.

Cc php bin i morphological: ngoi cc php bi n i c

bn nh l Erode, Dilate cn c cc php bin i phc tp

hn bng cc kt hp 2 php bin i Erode v Dilate nh l :

o Open: open(A,B) = dilate(erode(A,B),B)

o Close: close(A,B) = erode(dilate(A,B),B)o Morphological gradient:

morp_grad(A,B) = dilate(A,B) erode(A,B)

o Top hat: tophat(A,B) = A erode(A,B)

o Black hat: blackhat(A,B) = dilate(A,B) A

Cc b lc nhiu: s dng cc b lc thng dng nh l

Median, Gausian.... Cc php chuyn i cc khng gian mu: cc khng gian

mu m OpenCV h trl: Gray, RGB, HSV, YCrCb, XYZ,

Lab, Bayer.



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Cc php bin i c bit nh l : php bin i Hough,

Fourier...

Cc hm v Histogram

Ni chung cc hm x lnh ca OpenCV l mt phn trong th

vin IPL.

2.2.3 Cc hm v phn tch vn ng v theo vt i tng

Cc hm dng trong phng php tr nn.

Cc hm v theo vt i tng da theo thut ton

MeanShift, Camshift, v Snake.

Cc hm dng tnh ton Optical Flow da vo cc thut

ton ph bin: Horn & Schunck, Lucas & Kanade, ...

Cc hm c lng trng thi da vo b lc Kalman

2.2.4 Cc hm v nhn dng i tng

Cc hm v nhn dng i tng theo phng php PCA nh

l: tnh ma trn tng quan, tnh cc vector ring.....

Cc hm v nhn dng i tng theo m hnh Makp n.2.2.5 Cc hm v giao din v thu nhn video

Cc hm ny nm trong th vinHighgui v th khi s dng cc

hm ny bn phi khai bo : #include highgui.h v thit lp

cc lin kt ti cc file th vin cn thit l highgui.lib v

highgui.dll. Cc hm cbn trong th vin ny l:

Cc hm v Window: to ca s mi, hy mt ca s, lyHandle ca mt ca s, ly tn ca mt ca s....

Cc hm v x l file nh: nh l c mt nh t file v lu

vo cu trc IplImage, hm hin mt nh ln mn hnh, lu



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mt nh xung mt file, hay chuyn i khng gian mu ca

nh....

Cc hm v nhp xut video: bao gm cc hm ly d liu t

mt file AVI, ly d liu t camera v lu vo cu trc

CvCapture, hm ly mt Frame t cu trc CvCapture, hm

lu d liu video xung mt file AVI..

Ngoi ra trong th vin highgui cn c cc lp c vit di

dng hng i tng d dng s dng nh l lp

CvvImage..

Cc hm c gii thiu trn l cc hm cbn trong OpenCV.

Ngoi ra cn c mt s hm c bit c mrng sau mi phin bn ci tin

ca n. OpenCV cn cung cp cho chng ta rt nhiu cc v d rt hu ch. Nu

cc bn quan tm th vin ny v mi bt u lm quen th c th tham kho

bi vit: A step-by-step guide to the use of the Intel OpenCV library

and the Microsoft DirectShow technology ca Robert Laganiere a

chhttp://www.site.uottawa.ca/~laganier/tutorial/opencv+directshow/ . Hoc l

tham gia vo nhm OpenCV ti a chhttp://groups.yahoo.com/group/opencv .
http://www.site.uottawa.ca/~laganier/tutorial/opencv+directshow/http://groups.yahoo.com/group/opencvhttp://groups.yahoo.com/group/opencvhttp://www.site.uottawa.ca/~laganier/tutorial/opencv+directshow/

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