matlab presentation for upload

8/2/2019 Matlab Presentation for Upload

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TITLE SLIDE

Introduction to MATLAB and its ComputationalPowers in Image Processing

By :-

blue ink infotech pvt. ltd.

www.blueink.inJoin us at facebook:-

blueink infotech


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COMPANY INTRODUCTION

blue ink infotech pvt. ltd. has started itsjourney in early 2008. Blue Ink is an incubateecompany of Technology Business Incubator,

KIET. Companys work domains are software

development, web development, projectdevelopment and training, e-learning and

content management, Embedded Systems.

Prepared by : Ashutosh K. [email protected]


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Outline

Part I: Introduction and Overview (Case Study) Part II: MATLAB Desktop

Part III: Types of Files

Part IV: Matrix Manipulations, CommonFunctions, Plots in MATLAB

Part V: Image Processing Commands

Part VI: Model Demonstration



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What is MATLAB?

MATLAB (MATrix LABoratory) is a high-performance language fortechnical computing. It is an interactive system whose basic dataelement is an array that does not require dimensioning. Allows tosolve many technical computing problems, examples of whichinclude:

Matrix manipulation

Finding the roots of polynomials Digital signal processing applications (toolbox) Plotting: x-y and polar, 3D graphics

Particularly helpful for: Algorithm development, Modeling, simulation, and prototyping,

Data acquisition Data analysis, exploration, and visualization, Application development, including graphical user interface building.



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Levels of Image Processing

There are no clear-cut boundaries in thecontinuum from image processing at one endto computer vision at the other. However, a

useful paradigm is to consider thee types ofcomputerized processes:

Low level processes

Mid level processes

High level processes



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Low level processes

A low level processes involve primitive operations, such asimage preprocessing to reduce noise, contrastenhancement, and image sharpening. A low-level process ischaracterized by the fact that both its inputs and outputstypically are images.

Mid-level processes on images involve tasks such assegmentation (partit ioning an image into regions orobjects), description of those objects to reduce them to aform suitable for computer processing, and classification(recognition) of individual objects. A mid-level process ischaracterized by the fact that its inputs generally are

images, but its outputs are attributes extracted from thoseimages (e.g. edges, contours, and the identity of individualobjects).



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High Level Processes

High level processing involves making senseof an ensemble of recognized objects, as inimage analysis, and, at far end of continuum,

performing the cognit ive functions normallyassociated with human vision.



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Applications of Image Processing

Weather forcasting

Machine vision measuring distance of objects

Object detection

Finding an odd product on the conveyor belt

VIDEO DEMO



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MATLAB System

MATLAB system consists of five main parts Development Environment

Set of tools and facilities that help you use MATLAB functions andfiles.

MATLAB Mathematical Function Library Collection of functions like sum, sine, cosine, and complex

arithmetic, matrix inverse, matrix eigenvalues, and fast Fouriertransforms.

The MATLAB Language High-level matrix/array language with control flow statements,

functions, data structures, input/output, and object-orientedprogramming features.

Graphics Provides extensive facilities for displaying vectors and matrices as

graphs, as well as annotating and print ing these graphs.

Application Program Interface (API)



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MATLAB DesktopWhen you start MATLAB, MATLAB desktop appears,containing tools (graphical user interfaces) for managingfiles, variables, and applications associated with MATLAB.



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Help in MATLAB

>> help Shows help document for a given functionExample: help mean

>> lookfor Searches all the help documents for a givenkeywordExample: lookfor average

>> demo



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Types of Files

.m file - command window is used to executesingle command. But if it is required toexecute/save a program, we need to generate

a matlab programming file which is saved asxyz.m (mat file)



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SIMULINK Simulink software models, simulates, and analyzes

dynamic systems. It enables you to pose a question about a

system, model thesystem, and see what happens. With Simulink, you can easily build models from scratch, or

modify existing models to meet your needs. Simulinksupports linear and nonlinear systems, modeled incontinuous time, sampled time, or a hybrid of the two.Systems can also be multirate having different parts that

are sampled or updated at different rates. Thousandsof scientistsand engineersaround the world use

Simulink to model and solve real problems in a variety ofindustries, including:

Aerospace and Defense Automotive Communications Electronicsand Signal Processing Medical Instrumentation



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Variables: Scalars, Vectors andMatricesReal Scalars

>> x = 5

x = 5Complex Scalars>> x = 5+10j %5+10i works, as does 5+10*jx =5.0000 +10.0000iRow Vector (1 x 3)>> x = [ 1 2 3 ]x =

1 2 3Column Vector ( 3 x 1)

>> x = [ 1 ; 2 ; 3 ]; %; supresses output>> xx =123Matrix (3 x 3)>> x = [ 1 2 3 ; 4 5 6 ; 7 8 9 ]x =

1 2 34 5 67 8 9

Note: Variable Names are case sensitive



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Generating Vectors and the Colon Operator

>> x = [ 0 : 0.2 : 1 ] % 0 to 1 in increments of 0.2

x =

0 0.20 0.40 0.60 0.80 1.00

>> x = linspace(0, 1, 6) % 6 points from 0 to 1 on a linear scale

x =

0 0.20 0.40 0.60 0.80 1.00



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Generating Matrices>>B = [ 1 2 ; 8 9 ]

ans =1 2

8 9

>>ones(2,2) % generatesan all ones2 x 2 matrixans =

1 1

1 1

>>zeros(2,3) % generatesan all zero 2 x 3 matrixans =

0 0 0

0 0 0

>>rand(3,3) % generatesa random3 x 3 matrixans =

0.4447 0.9218 0.4057

0.6154 0.7382 0.93550.7919 0.1763 0.9169



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Accessing Matrix Elements

>> A= [ 1 2 3 ; 4 5 6 ; 7 8 9];

>> x = A ( 1, 3 ) %A(,)

x =3

A =

1 2 3

4 5 6

7 8 9



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Complex Number Operations

>> x = 3+4j

>> abs(x) %Absolute value.x = 5

>> angle(x) %Phase angle (in radians).

x = 0.9273

>> conj(x) %Complex conjugate.

x = 3-4j

>> imag(x) %Complex imaginary part.x = 4

>> real(x) %Complex real part.x = 3



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Some Useful Functions

Some useful math functions:

sin(x), cos(x), tan(x), atan(x), exp(x), log(x), log10(x), sqrt(x)

>> t = [ 0 : 0.01 : 10 ];

>> x = sin ( 2 * pi * t );

Some useful matrix and vector functions:

>> size (A)

ans=

3 3

>> length ( t )

ans=

1001

A =

1 2 3

4 5 6

7 8 9



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What is sum(A')' ?

A =

1 2 3

4 5 6

7 8 9

More Operators and Functions

For vectors, SUM(X) is the sum of the elements of X. For matrices, SUM(X) is a row vector withthe sum over each column.

>> sum ( A )ans =

12 15 18

>> sum ( ans ) % equivalent to sum(sum(A))

ans =45

>> A % equivalent to transpose(A)ans =

1 4 72 5 83 6 9

>> diag(A)ans =159



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Roots of Polynomials

Find the roots of the polynomial: 13 x3 + 25 x2 + 3 x + 4

>> C = [13 25 3 4];>> r = roots(C)r =

-1.8872

-0.0179 + 0.4034i-0.0179 - 0.4034i



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>> x = [ 0 : 0.001 : 2*pi ];>> y = sin ( x );>> plot (x,y) ;

Continuous Time Plots

0 1 2 3 4 5 6 7-1

-0.5

0

0.5

1

The plot function has different forms, depending on the input arguments.If y is a vector, plot(y) produces a piecewise linear graph of the elements

of y versus the index its elements. If you specify two vectors as arguments,plot(x,y) produces a graph of y versus x.



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Discrete Time Plots Stems Stem function is very similar to plot. It is used to plot discrete time

sequences. For more info: help stem Example:

>> k = [ 0 : 30 ] ;

>> x = sin ( k / 5 ) ;

>> stem ( k, x)

0 5 10 15 20 25 30-1

-0.5

0

0.5

1

0 k 5

x[

k

]

x [ k ] = sin ( k / 5 ) for 0 k 5



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0 1 2 3 4 5 6 7

-1

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8

1

sin(x)

sin(x-.25)

sin(x-.5)

Multiple Data Sets in One Graph

Mult iple x-y pair arguments create multiple graphs with a single callto plot. For example, these statements plot three related functionsof x, each curve in a separate distinguishing color.

x = 0:pi/100:2*pi;

y = sin(x);

y2 = sin(x-.25);y3 = sin(x-.5);

plot(x,y,x,y2,x,y3)

legend('sin(x)','sin(x-.25)','sin(x-.5)')

Thelegend command provides an easy

way to identify the individual plots.



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Function

Syntax function [out1, out2, ...] = funname(in1, in2, ...)

Description

function [out1, out2, ...] = funname(in1, in2, ...)defines function funname that accepts inputs in1,in2, etc. and returns outputs out1, out2, etc.

Demo Example



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Precious Tip 1

Notice that the array subscripts in Matlab start from 1and not 0 as is the case in C.

Illustration:

>> A = [1 2 3 4];>> A(0) % This command will result in syntax error

The first index is 1 and not 0.

>> A(1)ans = 1



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Precious Tip 2

Tip 2: MATLAB is designed to perform vector operations. Long for-loops on theother hand are not efficient. You can see that by comparing the following two piecesof code that do the very same thing: filling an array A with 5s.

X = 5 * ones(10^7,1);

OR

Y = zeros(10^7,1);for i = 1 : length(A)

Y(i) = 5;end

Try running the above two pieces of codes (red and blue one) in Matlab (Just copy andpaste on the command prompt). Compare the time it takes for Matlab to executethem. What do you conclude?Note: the results of two pieces of code are the same!



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IMAGES



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Pixel co-ordinate The most convenient method for expressing locations in an

image is to use pixel coordinates. In this coordinate system,

the image is treated as a grid of discrete elements, orderedfrom top to bottom and left to right, as illustrated by thefollowingfigure.

Pixel coordinate system



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Image as Matrices

)1,1(....)1,1()0,1(

....

)1,1(....)1,1()0,1()1,0(....)1,0()0,0(

),(

NMfMfMf

NfffNfff

yxf

Each element of this array is called and image element, picture element, pixel or pel.A MATLAB image can be represented as a MATLAB matrix:

),(....)2,()1,(....

)1,1(....)1,1()1,2(

),1(....)2,1()1,1(

),(

NMfMfMf

Nfff

Nfff

yxf



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Binary Image



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Image Processing Commands

Reading Images

Images are read into the MATLAB environment using function imread, whosesyntax is

Imread(filename)

Here, filename is a string containing the complete name of the image file

(including anyapplicable extension). For example, the command line

>> f = imread (flower.jpg) ;

Readsthe JPEGimage flower into image array f. The semicolon at the end ofa command line is used by MATLAB for suppressing output. If a semicolon is

not included, MATLABdisplays the results of the operation(s) specified in thatline. File must be located in the current directory or in the MATLAB searchpath.



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Displaying Images

>> imshow (f)

>> imshow (flower.jpg)

This command displays the image stored in the graphics file. The file mustcontain an image that can be read by imread. The file must be in the currentdirectory or on the MATLAB path.

>> whosf

Name Size Bytes Class Attributes

f 350x350x3 367500 uint8

whos f extract basic information about the image, and display it .



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Writing Images

Images are written to disk using function imwrite, which has the followingbasic syntax:

imwrite (f, filename)

e.g. imwrite(f, flower1.png)

Here, the above command writes f to a png file named flower1.

If filename contains no path information , then imwrite saves the file in thecurrent working directory. Most of the work deals with JPEG or TIFF

images, so we focus attention here on these two formats.




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Image compression

A more general imwrite syntax applicable only to JPEG images is

>> imwrite (f, filename, quality, q)

Where q is an integer between 0 and 100 (the lower the number the higher

the degradation due to JPEG compression).

In order to reduce storage and transmission time, it is important that theimages be compressed as much as possible while not degrading their

visual appearance beyond a reasonable level. In this case reasonablemeans no perceptible false contouring.




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Compression

flower.jpg (184kb) flower50.jpg ( 20 kb)imwrite(f, flower50.jpg , quality , 50)

flower30.jpg ( 16 kb)



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Functions

The function definit ion line has the form:

Function[outputs] = name (inputs)



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Proposed Projects of Image Processing

Any object shape & color detection. To judge size, shape & orientation of an object. Automatic attendance system using image processing (face

recognition). Traffic light controller using image processing (based upon no. of

vehicles on the road). Measure the distance of objects from camera (obstacle avoidance). Signature recognit ion. Safety alarm for a driver in drowsiness condition(based on eye

blinking rate). Security system.

Object Tracking



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Object Tracking



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Lane Departure System



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Car Tracking



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For further queries you can mail me at-

[email protected]

Or call at- 9999645463


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