Hiephv - Digital Image Processing - Chapter 1. Gioi Thieu Chung
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Transcript of Hiephv - Digital Image Processing - Chapter 1. Gioi Thieu Chung
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8/24/2011
1
Hong Vn Hip
B mn K thut my tnh
Vin Cng ngh thng tin v Truyn thng
Email: [email protected]
X l nh
Mc ch
Cung cp cc kin thc c bn v x l nh s
Cung cp cc k nng cn thit gip sinh vin c th vit c cc ng dng x l nh Matlab
C++, C#
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Yu cu
Cc kin thc ton hc Matrix v vector
Xc sut thng k
Cc kin thc v x l tn hiu
K nng lp trnh Matlab
C, C++, C#
Ti liu tham kho Books Digital Image Processing, by: R. C. Gonzalez and R. E.
Woods, 3rd Ed., 2008, Prentice Hall Digital image processing using Matlab by Gonzalez
Journals IEEE Trans. on Image Processing IEEE Transactions on Pattern Analysis and Machine
Intelligence
Conferences ICIP ICIAP CVPR ICPR ICCP ICCV
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nh gi
Thi: 70 %
Bi tp ln: 30 % ti: Tun th 4, 5
Bo v BTL: Tun 15
Chia nhm thc hin: (2 ngi 3 ngi)
Ni dung Chng 1. Gii thiu chung Chng 2. Thu nhn & s ha nh Chng 3. Ci thin & phc hi nh Chng 4. Pht hin tch bin, phn vng
nh Chng 5. Trch chn cc c trng trong
nh Chng 6. Nn nh Chng 7. Lp trnh x l nh bng
Matlab v C
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Chng 1. Gii thiu chung
Khi nim x l nh
Cc vn ca x l nh
Gii thiu mt s ng dng ca x l nh
Matrix v vector
Mt s khi nim c bn
Khi nim x l nh
Khi nim nh
Khi nim nh s
Phn bit nh tnh, nh ng
Khi nim x l nh
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Khi nim nh
Thng tin v vt th hay quang cnh c chiu sng m con ngi quan st v cm nhn c bng mt v h thng thn kinh th gic
Biu din nh v mt ton hc: o F(x, y): trong x, y l ta khng gian 2 chiu
v f l ln ca chi (nh n sc), mu (i vi nh mu)
o Ch : x, y bin thin lin tc v f cng lin tc
Khi nim nh s
nh s l nh thu c t nh lin tc bng php ly mu v lng t ha
pixel
Gray level
Original picture Digital image
f(x, y) I[i, j] or I[x, y]
x
y
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Khi nim nh s (tip)
Khi nim nh s (tip)
Mt nh s thng c biu din nh mt ma trn cc im nh
Trong mi im nh c th c biu din bng 1 bit (nh nh phn)
8 bit (nh a mc xm)
16, 24 bit (nh mu)
nh c biu din nh di dng ma trn cc im nh gi l nh bitmap
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Khi nim nh s (tip)
Mt cch biu din khc ca nh s l di dng vector (nh vector) Khng biu din nh di dng ma trn cc
im nh m hng n i tng trong nh
Thng bao gm cc thnh phn c bn nh hnh trn, ng thng
Circle(100, 20, 20) Line(xa1, ya1, xa2, ya2)
Line(xb1, yb1, xb2, yb2)
Line(xc1, yc1, xc2, yc2)
Line(xd1, yd1, xd2, yd2)
nh bitmap vs nh vector
Vector Biu din cc hnh n
gin
Tnh ton nhanh
ui file: *.EPS, *.AI, *CDR, or *.DWG.
Bitmap
Biu din cc hnh phc tp hn
Tnh ton chm
Hn ch khi zoom, cc php bin hnh
ui file: BMP, JPG
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Phn bit gia nh tnh v chui nh ng (chui nh)
Khi nim x l nh
Nng cao cht lng hnh nh theo mt tiu ch no (Cm nhn ca con ngi)
Phn tch nh thu c cc thng tin c trng gip cho vic phn loi, nhn bit nh.
Hiu nh u vo c nhng m t v nh mc cao hn, su hn.
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17
Lch s v x l nh
Bt ngun t hai ng dng: nng cao cht
lng thng tin hnh nh v x l s liu
cho my tnh
ng dng u tin l vic truyn thng tin
nh bo gia London v New York vo nm
1920 qua cp Bartlane.
M ha d liu nh khi phc nh
Thi gian truyn nh: T 1 tun 3 ting
18
Lch s v x l nh
Anh s c tao ra vao nm 1921 t
bng ma hoa cua mt may in in tin.
(McFarlane)
Anh s c tao ra vao nm 1922 t card
uc l sau 2 ln truyn qua ai Ty
Dng.
Mt vai li co th nhin thy c.
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19
Lch s v x l nh
Anh 15 cp xam c truyn t Lun n n New York, nm 1929. (McFarlane)
Trong khoang thi gian nay, ngi ta chi noi n anh s,
ch cha cp gi n x ly anh s, vi mt ly do n gian:
may tinh cha co.
H thng u tin c kha nng m ha
hnh anh vi mc xm l 5 v tng ln 15
vo nm 1929
20
Lch s v x l nh
Nm 1964, nh mt trng c a v tri t thng
qua cc my chp ca tu Ranger 7 ca Jet Propulsion
Laboratory (Pasadena, California) cho my tnh x
l: Chnh mo.
Anh u tin cua mt trng c chup bi tau
vu tru My Ranger 7, vao 9 gi 09 phut sang
ngay 31/7/1964 (ngun: NASA)
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21
Lch s v x l nh
Song song vi cac ng dng trong kham pha khng gian, cac k thut x ly nh cng a bt u vao cui nhng nm 1960 va u nhng nm 1970 trong y hc, theo doi tai nguyn trai t va thin vn hc.
n nay x l nh a c mt bc tin di trong nhiu ngnh khoa hc, t nhng ng dng n gin n phc tp.
M hnh h thng x l nh
Nhn t pha ngi dng
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M hnh h thng x l nh
Cc giai on trong x l nh
Camera
Sensor
Thu nhn
nh S ha
Phn tch
nh
i snh
Nhn dng
H
quyt nh Lu tr
Lu tr
M hnh h thng x l nh
Image Acquisition
Discretization/Digitization
Quantization
Compression
Image enhancement
and restoration
Image Segmentation
Feature Selection
Image Representation
Image Interpretation
Phn on nh: phn tach cac i tng trong nh
Rt trch nhng c trng ca nh
Biu din (gan nhan) nh da vao c trng nh
Nhn dng, gii thch
Thit b cm bin thu nhn nh
Lng t ha, nn nh
Nng cao cht lng nh ( tng phn, nhiu,)
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Cc cp trong x l nh
Level 0: Image acquisition (thu nhn nh, ly mu, lng t ha, nn)
Level 1: Image to Image (tng cng nh, khi phc nh, phn on nh)
Level 2: Image to parameter (trch chn c trng: feature extraction, feature selection)
Level 3: Parameter to decision (recognition, interpretation)
M hnh h thng x l nh
Nhng vn cn gii quyt (cn hc)
Image
Acquisition
Image
Enhancement
Image
Restoration
Image
Compression
Image
Segmentation
Representation
& Description
Recognition &
Interpretation
Knowledge Base
Preprocessing low level
Image
Coding
Morphological
Image Processing
Wavelet
Analysis
High-level IP
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Cc vn ca x l nh
Thu nhn nh, s ha nh (image aquisition) H thng chp nh, tn hiu nh H thng s ha nh: Cc phng php ly
mu, lng t ha
Ci thin nh, khi phc nh, lc nhiu (tin x l image pre-processing) Cc php x l im nh
Cc php x l trn min khng gian
Cc php x l trn min tn s
Cc vn ca x l nh Phn tch nh Trch chn c trng (feature extraction)
Biu din, m t nh (image representation, image description)
Phn lp nh (image classification)
Nhn dng nh (image recognition)
M ha, nn nh Cc phng php nn nh, cc chun nn nh
Truyn thng nh
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X l nh v cc lnh vc lin quan
Phn bit mt s khi nim Image formation: object in image out (level 0)
Image processing (level 0, 1) Image in image out
Image analysis (level 1, 2) Image in features out
Computer vision (level 2, 3) Image in interpretation out
Computer graphic Number in image out
Visualization Image in representation out
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Cc ng dng ca x l nh
X l nh v tinh, nh vin thm
Thin vn, nghin cu khng gian, v tr
Thm d a cht
Lnh vc y t
Robot, t ng ha
Gim st, pht hin chuyn ng
Image v video retrieval
Cc ng dng ca x l nh
Bc x ph in t ca nh sng
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33
Cc ng dng ca x l nh
nh Gamma
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Cc ng dng ca x l nh
nh Gamma a b
c d
nh phng x
(a) Qut b xng
(b) Chp PET (Positron Emission Tomography)
nh thin vn
(c) Chm sao thin nga
nh phn ng ht nhn
(d) S bc x tia Gamma t l phan ng
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35
Cc ng dng ca x l nh (tip)
nh tia X (nh X-Quang)
H thng may chp anh X-Quang
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Cc ng dng ca x l nh (tip)
nh tia X (nh X-Quang)
Anh X-Quang chp lng ngc Anh X-Quang chp ham mt
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37
Cc ng dng ca x l nh (tip)
nh tia X (nh X-Quang)
H thng may chp anh ct lp CT
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Cc ng dng ca x l nh (tip)
nh tia X
Anh chup ct lp CT
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39
Cc ng dng ca x l nh (tip)
nh trong di cc tm a c
d
(a) Trng binh thng
(b) Trng bnh than
(c) Chm sao thin nga
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Cc ng dng ca x l nh (tip)
nh hng ngoi
Anh hng ngoi chp u con mo
Anh hng ngoi chp u con cho
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Cc ng dng ca x l nh (tip)
nh hng ngoi
Anh hng ngoi chp b mt trai t. Nhng ni co nh sng mnh la nhng ni co ngun nhit ln.
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Cc ng dng ca x l nh (tip)
nh hng ngoi
Anh hng ngoi chp khng gian trn b mt trai t. Anh nay cho bit lng hi nc tich t trong khng gian, phc v cho vic d bao thi tit.
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Cc ng dng ca x l nh (tip)
Trong vng nh sng nhn thy Ci thin nh
Cc ng dng ca x l nh (tip)
Gim nhiu
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Cc ng dng ca x l nh (tip)
Cc ng dng ca x l nh (tip)
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Cc ng dng ca x l nh (tip)
Cc ng dng ca x l nh (tip)
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Cc ng dng ca x l nh (tip)
Cc ng dng ca x l nh (tip)
Nhn dng ch vit
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Cc ng dng ca x l nh (tip)
Cc ng dng ca x l nh (tip)
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Gii thiu mt s h thng retrieval
Google image similarity
IMARS http://www.alphaworks.ibm.com/tech/imars
MediaMill http://www.science.uva.nl/research/mediamill/demo/
crossbrowser.php
Demo1
Demo2
CuVid http://apollo.ee.columbia.edu/cuvidsearch/login.php
Video summarization
Matrix v vector
Cc php x l nh thc cht l cc php tnh ton trn cc ma trn v cc vectors
review li mt s khi nim trong ton hc v matrix v vector
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Mt s khi nim Khi nim ma trn:
m: dng, n ct
A l vung (square) nu m = n
A l ma trn ng cho (diagonal): nu cc phn t khng nm trn ng cho = 0, c t nht mt phn t trn ng cho 0
A l ma trn n v (identity - I): nu diagonal v cc phn t trn ng cho u = 1
Mt s khi nim (tip) =
Ma trn chuyn v (transpose): dng ct, ct dng, k hiu:
Ma trn vung A i xng (symetric) nu A =
Ma trn nghch o (Inverse): X l inverse ca A nu: XA = I v AX = I
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Mt s khi nim (tip)
Vector ct (column vector) l ma trn mx1
Vector hng (row vector) l ma trn 1xm
Cc php tnh trong ma trn
A, B cng kch thc m x n C = A + B C kch thc m x n v = +
D = A B D kch thc m x n v = -
A(m, n); B(n, q)
C = AB C kch thc m x q v
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Cc php tnh trong ma trn
Cho 2 vector a, b cng kch thc
Tch v hng 2 vector (inner product dot product) c nh ngha nh sau
Khng gian vector (vector spaces)
Khng gian vector c nh ngha l mt tp vector V v tha mn cc iu kin sau y iu kin A o 1. x + y = y + x vi mi vector x v y trong khng
gian
o 2. x + (y + z) = (x + y) + z
o 3. Tn ti duy nht vector 0: x + 0 = 0 + x = 0
o 4. x + (-x) = (-x) + x = 0
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Vector spaces (tp)
iu kin B 1. c(dx) = (cd)x vi mi s c, d v vector x
2. (c + d)x = cx + dx
3. c(x + y) = cx + cy
iu kin C 1x = x
Vector spaces (tip) T hp tuyn tnh (linear combination) ca
cc vectors: 1, 2, ,
Vetor v gi l ph thuc tuyn tnh (linearly dependent) ca cc vectors 1, 2, , nu v c th vit l t hp tuyn tnh ca tp vector ny. Ngc li v l c lp tuyn tnh ca tp vector trn (linearly independent)
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Vector spaces (tip)
Tp vector c s (basis vector set) trong khng gian V cho php to ra vector v bt k trong khng gian V d: khng gian vector 3, vector
C th c to bng t hp tuyn tnh ca 3 vectors c s:
Chun ca vector (vector norm)
Vector norm ca vector x : k hiu cn tha mn cc iu kin sau
Cng thc tnh chun ca vector c nhiu, cng thc hay dng: 2-norm (khong cch Euclidean)
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Quan h gia 2 vector Cosin
Suy ra cch tnh khc ca tch v hng
(inner product)
2 vector gi l trc giao (orthogonal) vi nhau nu v ch nu tch v hng = 0
2 vector gi l trc chun (orthonormal) nu Chng trc giao Norm ca mi vector = 1
Quan h gia cc vectors
Tp cc vector l trc giao nu mi cp 2 vector trc giao tng i mt
Tp cc vector l trc chun nu mi cp 2 vector trc chun tng i mt
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Tnh cht ca vector trc giao
Nu l tp vector trc giao hoc trc chun, th vector v bt k c th c biu din bng t hp tuyn tnh ca cc vector trc giao trn
Tr ring vector ring (Eigen values - eigenvectors)
Cho ma trn vung M, nu tn ti mt s v vector e sao cho:
Th: gi l tr ring ca ma trn M
e: l vector ring ng vi tr ring
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Eigenvalues v eigenvectors (tip)
Cng thc tnh: Da trn biu thc
Trong : det l nh thc
V d: Tm tr ring, vector ring ca ma trn sau:
Eigenvalues v eigenvectors (tip)
Gii:
Vi = 3, tm vector ring tng ng
x = y,
Suy ra: = 1 and = 3
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Tnh cht ca eigenvalues v eigenvectors
Ma trn vung A (m x m) c m eigenvalues phn bit th m eigenvectors tng ng s trc giao vi nhau
M l ma trn vung i xng, A l ma trn c cc hng l cc vector ring ca ma trn M th (nu ma trn vung i xng th cc vector ring s trc chun - orthonormal)
.
Tnh cht ca eigenvalues v eigenvectors
M l ma trn vung i xng, A l ma trn c cc hng l cc vector ring ca ma trn M.
D l ma trn ng cho, vi cc phn t trn ng cho l cc tr ring (eigenvalues) ca ma trn M
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Tnh cht ca eigenvalues v eigenvectors
A l ma trn vung
.
Mt s khi nim c bn
im nh (pixel)
phn gii (resolution)
Mc xm (gray scale)
Ln cn (neighbors)
Lin thng (conectivity)
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Mt s khi nim c bn (tip)
Pixel: Picture element l n v nh nht cu to nn nh s Mi pixel c ta (x,y) v gi tr cng
sng hoc mu sc ti im
phn gii ca nh: S pixel c trong nh to nn bc nh Thng ghi di dng: m x n o m: s pixel trn chiu rng nh
o n: s pixel trn chiu cao nh
phn gii cng cao, nh cng sc nt
Mt s khi nim c bn (tip)
phn gii (resolution)
a b c
d e f
(a) 1024 1024
(b) 512 512
(c) 256 256
(d) 128 128
(e) 64 64
(f) 32 32
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Mt s khi nim c bn (tip)
Mc xm (gray)
Mc xm l kt qu ca vic m ho ng vi mt
cng sng ca mi im nh vi mt gi tr s.
Thng thng nh c m ho di dng 16, 32,
64 hay 256 mc.
V d: ti im nh ta (20, 40) c mc xm l
60, ti im nh ta (30, 40) c mc xm l 23,
...
Mt s khi nim c bn (tip) Ln cn (neighbours)
Mt im nh p ti ta (x, y) c
o 4 ln cn ngang - dc ca p: K hiu l N4(p)
(x+1,y), (x-1,y), (x,y+1), (x,y-1)
o 4 ln cn cho ca p: K hiu l ND(p)
(x+1,y+1), (x+1,y-1), (x-1,y+1), (x-1,y-1)
o 8 ln cn ca p: K hiu N8(p)
l s kt hp ca N4(p) v ND(p)
(x+1,y), (x-1,y), (x,y+1), (x,y-1),
(x+1,y+1), (x+1,y-1), (x-1,y+1), (x-1,y-1)
x
x p x
x
x x
p
x x
x x x
x p x
x x x
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Mt s khi nim c bn (tip)
Lin thng: Cc im trong nh gi l lin thng vi nhau nu L ln cn ca nhau
V c cng gi tr mc xm