DIP_Lect1

7/30/2019 DIP_Lect1

1/57

g a

mage

rocess ng

ComputerGraphicsandAnimation

RefBook:

Digital

Image

Processing

Rafael

C.Gonzalez

DigitalImageProcessingUsingMatlab

Gonzalez

20%classParticipation:Quiz&Assg

30%MidTerm

50%

FinalExam

7/30/2019 DIP_Lect1

2/57

Howan

Image

is

formed

E ectromagneticwaveSpectrum

DIPApplication

Imagerepresentation

23/10/2010 2Dr N.H.Qazi IQRA University

7/30/2019 DIP_Lect1

3/57

WhyProcessing

mprovemento t ep ctor a n ormat on orhumanperception

g g u u application

23/10/2010 Dr.N.H.Qazi Iqra University 3

7/30/2019 DIP_Lect1

4/57

DIPhasacloserelationshiptoothersciencebaseddisciplinesintermsof

its

technical

content:

Electricalengineering

ComputerScience

ComputerVision

ArtificialIntelligence

ArtificialIntelligencehasbeenimplementedusingbothelectricalandmechanicalengineeringmeans.

u uresc ence

may

a ow

eimplementationofArtificial

Intelligencetheoryusingbiology.

23/10/2010 Dr.N.H.Qazi IqraUniversity 4

7/30/2019 DIP_Lect1

5/57

PrincipleElementsofDIP

theextension

of

digital

dimensions

possiblealso3Dimage

dimensionoftime,t.


7/30/2019 DIP_Lect1

6/57

Ste s

in

Di ital

Ima e

rocessin

ThebasicframeworkofaprojectinvolvingDigitalImageProcessingtoinvolvethefollowingpipeline:


7/30/2019 DIP_Lect1

7/57

Example:Howtoidentifypostcodefrom

Imageacquisition Firstweneedto roduceadi italima efroma a er

envelope.

This

can

be

done

using

either

a

CCD

camera,

or

a

scanner Basictaskstomaketheimagesuitableforprocessing.e.g

enhancecontrast,

removing

noise,

Identifying

region

of

interests.

Segmentation:

,

weextractfromtheIarge thatpartofitwhichcontainsjustthepostcode.

.


7/30/2019 DIP_Lect1

8/57

Example:Howtoidentifypostcode

fromenvelop

using

DIP

Extracting the particular features to differentiatebetween objects. Here we will be looking for curves,

holes and corners which allow us to distinguish the

different digits which constitute a postcode.

.

Assigning labels to objects based on their descriptors andassigning meanings to those labels. So we identify particular

digits, and we interpret a string of four digits at the end of theaddress as the postcode.


7/30/2019 DIP_Lect1

9/57

Imageprocessing

Threetypesofcomputerizedprocessingondigitalimagesaredefined: ow eve process ng,

midlevel

processing,

highlevelprocesses

LowLevelimageprocessing

Purpose

is

to

improve

the

visual

qualities

of

image

for

inputtotheprocessingunitisanimageandoutputisalsoanimage

Noisefiltering, ContentEnhancement


7/30/2019 DIP_Lect1

10/57

Image enhancement

Sharpeningordeblurring

anoutoffocusimage,

,orbrighteninganimage,

Noisefiltering, Highlightingedges

on en

n ancemen


7/30/2019 DIP_Lect1

11/57

Imageenhancement


7/30/2019 DIP_Lect1

12/57

Military

application

Military:useofimagingfordetectionofenemyassets,screeningofvessels,Airtoground

IRimaging.


7/30/2019 DIP_Lect1

13/57

Medical

application MedicalDiagnosis:Analysis

,

MRIand

CT

images

of

the

human(oranimal)bodyto

aidinmedicaldiagnosis

andtreatment.(looking

inside


7/30/2019 DIP_Lect1

14/57

Machinevisionapplication

inspectionofmanufacturedpartsonproductionlines.

AutomatedTargetdetectionandtracking

fin er rintreco nition Machineprocessingofaerialand

satelliteimageryforweatherrediction and cro assessment.

Boundarydetection Iftheboundary contourareidentified

identified.


7/30/2019 DIP_Lect1

15/57

Automatedinspection


7/30/2019 DIP_Lect1

16/57

Automatedinspection


7/30/2019 DIP_Lect1

17/57

Automatedinspection

broken

and

missingwire.

surface

characterstatis is

it

un ormorno .isnotuniform

differenttexture.


7/30/2019 DIP_Lect1

18/57

VideosequencingProcessing

Majoremphasisofimagesequenceprocessingisdetectionofmovin arts

Detectionand

tracking

of

moving

targets

for

Tofindoutthetrajectoryofamovingtarget

on tor ngt emovemento organboundariesinmedicalapplication

23/10/2010 Dr.N.H.Qazi IQRA University 18

7/30/2019 DIP_Lect1

19/57

(EM)spectrum.

approximately400and700nanometers.


7/30/2019 DIP_Lect1

20/57

ImageProcessing,Capture&Sampling

Imageprocessingisbyitsverynatureaverycomputationally

demanding

task. IntelMMXtechnolo ies

multiprocessorsystems (e.g.Intel

programmablehardwaresuchas


7/30/2019 DIP_Lect1

21/57

Thescene

reflects

radiation

towards

the

camera.

.

Whatcould

be

possible

sourceofillumination

Electromagnetic

spectrum


7/30/2019 DIP_Lect1

22/57

Imagecapturinganddisplaying

Captureimagefromcameraisconvertedinto

g ta ze

ormus ng

converter

an

convertedbacktoanaloguebeforedisplaying


.

7/30/2019 DIP_Lect1

23/57

Whatisanimage

Amultidimensionalsignal,commonly

Howto

store

an

image

in

acomputer

f(x,y)=r(x,y)*i(x,y)

Therecould

be

infinite

oint

and

infinite

valueoftheintensitywhattodo

SolutionisImageDigitalization:

samplingof

image

space

and

quantization

of

intensity


7/30/2019 DIP_Lect1

24/57

ImageDigitalization

Imagedigitizationistheprocessofconvertingananalogueimage,arrivingatacameralensandbeing

projectedontheimageplane,intoan2Darrayor

matrixofnumbers. Involvestwolevelsof:

1.SamplingorSpatialQuantization

. o oror n ens y grey eve uan za onorLuminanceQuantization


7/30/2019 DIP_Lect1

25/57

ImageDigitalization

Spatialquantization

corresponds

to

sampling

the

bri htnessoftheima eatanumberof ointsusuall a

CxR rectangulargrid.

ThisX*Y

dimensions

of

the

image

defined

the

number

of

pixelsusedtocoverthevisualspacecapturebythe

image.e.g.640x480,800x600,1024x768etc.

spatialresolution


7/30/2019 DIP_Lect1

26/57

Intensit

Quantization


7/30/2019 DIP_Lect1

27/57

ImageDigitalization Intensity

Quantization

Avoltagevalueisobservedforeachpixelcapturedat.

Thisvoltage

value

relates

to

the

amount

and

wavelengthoflightbeingprojectedthroughthecameralenstothatpointontheimageplane(rearplaneofcamera).

ofbinrepresentingtheintensityofcolor.

Grayscale(8bit)commonlyhas256differentgrey

eve s

rang ng

rom

ac

o

w e

Binaryimage(2bit):binaryimagehas2colour (blackorwhite


7/30/2019 DIP_Lect1

28/57

ImageDigitalization

TemporalResolution

thisis

the

number

of

images

captured

in

agiven

timeperiod.

Commonlyquotedasframespersecond(fps)

eachimage

is

referred

to

as

avideo

frame

(e.g.UKTVoperatesat25fps,2530fpsissuitableformostvisualsurveillance,higher

science/engineeringcapture.


7/30/2019 DIP_Lect1

29/57

Imagerepresentation

Adigitalimagef(x,y)isdiscreteredbothinspatialcoordinatedandintensity.

aDigitalimageisamatrixwhoserowandcolumn

indices

specify

apoint

in

the

image

andelement ixel valuere resentthe ra valueorintensityvalueatthatpoint

everypointintheimagespacehas

Imagesizeisrepresented256X256,512x512,1024X1024

Quantization

:

2

it

or

B W

,8

it

or

Gray

image24colorimages

23/10/2010 Dr.N.H.Qazi

Iqra

University 29

7/30/2019 DIP_Lect1

30/57

Greyscale.

Truecolour,orRGB

23/10/2010 Dr.N.H.Qazi

Iqra

University 30

7/30/2019 DIP_Lect1

31/57

T esofdi italIma e BinaryImage

Each ixelis ustblackorwhite.

Needsone

bit

per

pixel

suitablefortext,fingerprintsor

architectural

lans.

23/10/2010 Dr.N.H.Qazi

Iqra

University 31

7/30/2019 DIP_Lect1

32/57

TypesofdigitalImage GreyScale

Each ixelisshedof re from0 black to255

(white).

, .

Xrays,printedwork,natural objects

23/10/2010 Dr.N.H.Qazi

Iqra

University 32

7/30/2019 DIP_Lect1

33/57

T esofdi italIma e True

colour,

or

RGB.

.

Eachpixelhasaparticularcolourdescribed

by

the

amount

of

red,

green

and

blue

in

it.

Each ixel re uires 24 bits

Possiblecolours2553=166777216

23/10/2010 Dr.N.H.Qazi

Iqra

University 33

7/30/2019 DIP_Lect1

34/57

TypesofdigitalImage

Indexed.

theima ehasanassociatedcolourma orcolour

palette,

which

is

simply

a

list

of

all

the

colours

used

inthatimage.

Eachpixelhasavaluewhichdoesnotgiveitscolour

(as

for

an

RGB

image),

but

an

index

to

the

colour

in

themap.

23/10/2010 Dr.N.H.Qazi Iqra University 34

7/30/2019 DIP_Lect1

35/57

C*R*bwhere

C=Num ero pixe inx axis

R=Number

of

pixel

in

yaxis

b=numberofbitsusedtorepresentapixel.

, image

for

512

by

512

pixel

23/10/2010 Dr.N.H.Qazi

Iqra

University 35

7/30/2019 DIP_Lect1

36/57

=

512*512*1=26112bits=3264bytes=3.2kb=0.03MB

512*512*8=2097152bits=262144bytes=262kb=0.26

Mb

RGB

* * = = = .

23/10/2010 Dr.N.H.Qazi

Iqra

University 36

7/30/2019 DIP_Lect1

37/57

Matrix

A= 123 345 678

A(1,2) A(:,3)allelementinthethirdcolumn.

MATLABusesdataclassestorepresentthe

pixel

of

the

images

23/10/2010 Dr.N.H.Qazi

Iqra

University 37

7/30/2019 DIP_Lect1

38/57

7/30/2019 DIP_Lect1

39/57

ShortProgramme Load

rgb file,

convert

it

to

grey,write a

new

file.

a=imread('creek.tif');//load,observe a

a(100,200,2) returnsthesecondcolorvalue(green)atthepixelinrow100andcolumn200.Ifwewanta t eco orva uesatt atpo nt,

>>a(100,200,1:3)

Matlab allowsaconvenient

shortcut

for

listing

all

values

along

aparticular

dimension;justusingacolononitsown:

>>a(100,200,:)

Auseful

function

for

obtaining

RGB

values

is

impixel;

impixel(a,200,100)

im ixelinfo

23/10/2010 Dr.N.H.Qazi

Iqra

University 39

7/30/2019 DIP_Lect1

40/57

=

imwrite(b,'bgray','gif');//write

C ec t egrey eve reso ution

a=imread(bgray.gif'); figure,imshow(c,colormap(gray(64)))

, ,

figure,imshow(c,colormap(gray(512)))

23/10/2010 Dr.N.H.Qazi

Iqra

University 40

7/30/2019 DIP_Lect1

41/57

Convertingintobinaryimage

=

imageIto

abinary

image.

The

output

image

BWreplacesallpixelsintheinputimagewithluminancegreaterthanlevelwiththevalue1

(white)

and

replaces

all

other

pixels

with

the

va ue0 ac .Spec y eve nt erange 0,1 .

a=imread('D:\matlab_DIP\Winter.bmp');

k=im2bw(a,0.3) figure,imshow(k)

23/10/2010 Dr.N.H.Qazi

Iqra

University 41

7/30/2019 DIP_Lect1

42/57

imcontrast

AdjustContrast

tool

separatefigurethatisassociatedwiththe

grayscaleimage

in

the

current

figure,

called

the

targetimage

a=imread(blue');

b=rgb2gray(a) imcontrast(gca)

23/10/2010 Dr.N.H.Qazi

Iqra

University 42

7/30/2019 DIP_Lect1

43/57

= ' '.

b=rgb2gray(a); = 300:500,1:60

figure,imshow(ff)

Howtoaccessthecoordinatesforrgb image

= , ,

23/10/2010 Dr.N.H.Qazi

Iqra

University 43

7/30/2019 DIP_Lect1

44/57

grayimage

observe

value

of

rg b

. . .

23/10/2010 Dr.N.H.Qazi

Iqra

University 44

7/30/2019 DIP_Lect1

45/57

Lect2:PropertiesofImageRegion:

PixelNeighborhood

4neighborsN4(p)

Apixelpatcoordinates(x,y)hasfourhorizontalandvertical

neighbours

whose

coordinates

are

given

by

(x+1,y),(x1,y),(x,y+1),(x,y1)

Aboundarypixelhaslessnumberofpixel.Eachpixelsaun t stance rom x,y

DiagonalneighborsND(p)

(x+1,y+1),

(x+1,

y1),

(x

1,

y+1),

(x

1,

y1)

23/10/2010 Dr.N.H.Qazi

Iqra

University 45

7/30/2019 DIP_Lect1

46/57

Thesepoints,

together

with

the

4neighbors,

23/10/2010 Dr.N.H.Qazi

Iqra

University 46

C ti it

7/30/2019 DIP_Lect1

47/57

Connectivity

Isaimportant

property

used

for

establishing

Definingimagecomponents/regions

Usedingroupingofobjectwhichmeanswhetherapixelbelongstoparticularobject

Usingthis

connectivity

we

can

determine

the

boundariesoftheob ect itsareaetc.

23/10/2010 Dr.N.H.Qazi

Iqra

University 47

Connectivity

7/30/2019 DIP_Lect1

48/57

Connectivity

wop xe s

are

sa

o

econnec e

na

naryimageiftheyareadjacentinsomesense

,

Theirintensity

values

i.e gray

values

are

similar

Example:

two

points

p

and

q

will

be

connected

if

q

E

N p orpEN q an B p =B q

23/10/2010 Dr.N.H.Qazi

Iqra

University 48

Connectivityingraylevelimage

7/30/2019 DIP_Lect1

49/57

Connectivity in gray level image

.

canhaveanyvaluesfrom0to255. 4adjacency. Twopixelspandqwithvaluesfrom

Vare4adjacentifqisinthesetN4(p).

8adjacency. Two

pixels

pand

qwith

values

from

Madjacency:Ismodificationof8connectivity

connection.Twopointsaremconnectedifoneis

neighbourofotherandatthesametimetheydo. .

diagonalshould

not

have

any

common

four

neighbour.

23/10/2010 Dr.N.H.Qazi

Iqra

University 49

7/30/2019 DIP_Lect1

50/57

23/10/2010 Dr.N.H.Qazi

Iqra

University 50

7/30/2019 DIP_Lect1

51/57

Path

Letcoordinatesofpixelp:( ,y),andofpixelq:(s,t)

Apath

from

pto

qis

asequence

of

distinct

pixels

with

coordinates: (x0,y0),(x1,y1),......,(xn,yn) where

(x0,y0)=( ,y)& (xn,yn)=(s,t),

and(xi,yi)isadjacentto(xi1,yi1)1 i n

n

is

the

length

of

the

path

Regions.

Asetofpixelsinanimagewhereallcomponentpixelsareconnecte

Boundaryof

aregion

AsetofpixelsofaregionRthathaveoneofmore neighborsa areno n

23/10/2010 Dr.N.H.Qazi

Iqra

University 51

7/30/2019 DIP_Lect1

52/57

Euclideandistance between

pand

q:

, , , ,

(s,t),and

(u,v)

)()(),( tysxqpDe +=

equaltosome

,

containedin

adisk

of

radius

rcentered

23/10/2010 Dr.N.H.Qazi

Iqra

University 52

, .

7/30/2019 DIP_Lect1

53/57

cityblockdistance)

,

from(x,

y)

less

than

or

equal

to

some

value

r

, .

=

The

pixels

with

D4=1

are

the

4

neighbors

of

(x,y).How?

23/10/2010 Dr.N.H.Qazi

Iqra

University 53

7/30/2019 DIP_Lect1

54/57

|)||,max(|),(8 tysxqpD =

w atwi pixe swit D8 istance rom x,ylessthanorequaltosomevaluerform

ThepixelswithD8=1arethe8neighborsof(x,y).how

23/10/2010 Dr.N.H.Qazi

Iqra

University 54

7/30/2019 DIP_Lect1

55/57

Inmadjacency,Dmdistancebetweentwopointsisdefinedastheshortestmpathbetween thepoints.

uppose a wecons era acencyo p xe sva ue

(i.e.,V={1}). Ifp1andp3are0,thelengthoftheshortestmpath(them s ance e weenpan p s .

Ifp1is1,thenp2andpwillnolongerbemadjacentwhy

lengthof

the

shortest

m

path

becomes

3

path??? Pp1p2p4

betweenpand

p4

is

4.

In

this

case,

the

path

goes

through

thesequenceofpoints

23/10/2010 Dr.N.H.Qazi

Iqra

University 55

7/30/2019 DIP_Lect1

56/57

.

(a)Let

V={0,

1}

and

compute

the

lengths

of

, ,

pandq.Ifaparticularpathdoesnotexistetween

t ese

two

po nts,

explainwhy.

(b)Repeat

for

V={1,

2}.

23/10/2010 Dr.N.H.Qazi

Iqra

University 56

7/30/2019 DIP_Lect1

57/57

23/10/2010 Dr.N.H.Qazi

Iqra

University 57

Documents

DIP_Lect1