Getting started with image processing using Matlab

Introduction
 Cleve molar in 1984, Mathworks inc
 Introduced as a simulation tool
 Supports Graphical Programming
 Can be interfaced with other High
Level languages

Technology beyond the Dreams™ Copyright © 2006 Pantech Solutions Pvt Ltd.

Applications
• Aerospace
• Biometrics
• Medical
• Finance
• Control System
• Signal,Image,Audio and Video
• Neural networks,Fuzzy logic
• Animation

List of Companies
• ADOBE (Photoshop)
• NASA
• GE
• L&T
• ROBERT BOSCH
• PEPSI , COCACOLA (Neuro Marketing)


File Extensions
.fig
MATLAB Figure
.m
MATLAB function, script, or class
.mat
MATLAB binary file for storing variables
.mex
MATLAB executable (platform specific, e.g. ".mexmac" for the
Mac, ".mexglx" for Linux, etc.)
.p
MATLAB content-obscured .m file (result of pcode() )

Difference between C and Matlab
• Matlab is Proprietary compiler,C has open source.
• Inbuilt Functions in Matlab(Application Oriented).
• User friendly syntax.
• Fourth generation Programming Language tool.


Desktop Tools
• Command Window
– type commands

• Workspace
– view program variables
– clear to clear
– double click on a variable to see it in the Array Editor

• Command History
– view past commands
– save a whole session using diary

• Launch Pad
– access tools, demos and documentation


Command window


Change the current working
directory


Arithmetic operators
1) plus - Plus +
2) uplus - Unary plus +
3) minus - Minus -
4) uminus - Unary minus -
5) mtimes - Matrix multiply *
6) times - Array multiply .*
7) mpower - Matrix power ^
8) power - Array power .^
9) mldivide - Backslash or left matrix divide
10) mrdivide - Slash or right matrix divide /
11) ldivide - Left array divide .
12) rdivide - Right array divide ./


Relational operators
1) eq - Equal ==
2) ne - Not equal ~=
3) lt - Less than <
4) gt - Greater than >
5) le - Less than or equal <=
6) ge - Greater than or equal >=


Logical operators
1) Short-circuit logical AND &&
2) Short-circuit logical OR ||
3) and - Element-wise logical AND &
4) or - Element-wise logical OR |
5) not - Logical NOT ~
6) xor - Logical EXCLUSIVE OR
7) any - True if any element of vector is nonzero
8) all - True if all elements of vector are nonzero


BITWISE OPERATORS
1) bitand - Bit-wise AND.
2) bitcmp - Complement bits.
3) bitor - Bit-wise OR.
4) bitmax - Maximum floating point
integer.
5) bitxor - Bit-wise XOR.
6) bitset - Set bit.
7) bitget - Get bit.
8) bitshift - Bit-wise shift.


Vectors
a = [1 2 3 4 5 6 9 8 7] ;

t = 0:2:20
t = 0 2 4 6 8 10 12 14 16 18 20

b=a+2

b = 3 4 5 6 7 8 11 10 9

c=a+b
c = 4 6 8 10 12 14 20 18 16


Matrices
B = [1 2 3 4;5 6 7 8;9 10 11 12] ;

B=1234
5678
9 10 11 12

C = B'

C=159
2 6 10
3 7 11
4 8 12


Basic matrix operators
X = inv(E) ;%INVERSE OF THE MATRIX
[A,H] = eig(E) %eigen value &vector
p = poly(E) %polynomial
c = abs(y) ;
D=min(a);
D=max(a);

• Convolution
x = [1 2];
y = [1 4 8];
z = conv(x,y)
[xx, R] = deconv(z,y)


PLOT

t=0:0.25:7;
y = sin(t);
plot(t,y) ;
xlabel('x axis');
ylabel('y axis');
title('Heading');
grid on;
gtext('text');


IF LOOP
a=6;

if a > 6

disp('a is greater');

elseif a==0

disp('a is zero');

else

disp('a is smaller');

end

FOR LOOP
a=5;

for i=1:5

a=a+1

end

disp(a);

ANS a =10


While Loop
a=5;

while a < 10
a=a+1;

end

disp(a);

Ans a =10


Function
function c=add(a,b); function c=mul(a,b);
c=a+b; c=a*b;
return return

Main
a=5;
b=6;
c=add(a,b);
disp(c);
d=mul(a,b);
disp(d);


SWITCH CASE
method = 'Bilinear';
switch lower(METHOD)
case {'linear','bilinear'}
disp('Method is linear')
case 'cubic'
disp('Method is cubic')
case 'nearest'
disp('Method is nearest')
otherwise
disp('Unknown method.')
end

Ans Method is linear


SWITCH (NUMERICAL)
a=input('enter---->');
switch a
case 1
fprintf('one');
case 2
fprintf('two');
case 3
fprintf('three');
case 4
fprintf('four');
otherwise
fprintf('otherwise');
end


How to read an image
a =imread('cameraman.tif'); a =imread('flowers.tif');
imshow(a); imshow(a);
pixval on; pixval on;


How to read an audio file

a =wavread('test.wav');
wavplay(a,44100);
Plot(a);


How to read an video file

a=aviread('movie.avi');
movie(a);


Add two images

I = imread('rice.tif'); I = imread('rice.tif');
J = imread('cameraman.tif');
K = imadd(I,J,'uint16');
J = imadd(I,50);
imshow(K,[]) subplot(1,2,1), imshow(I)
subplot(1,2,2), imshow(J)


Subtract two images
I = imread('rice.tif');
Iq = imsubtract(I,50);
subplot(1,2,1), imshow(I)
subplot(1,2,2), imshow(Iq)


Convert image to gray and binary
clc;
clear;
close all
a= imread('flowers.tif');
subplot(2,2,1);
imshow(a);
subplot(2,2,2);
b=imresize(a,[256 256]);
imshow(b);
subplot(2,2,3);
c=rgb2gray(b);
imshow(c);
subplot(2,2,4);
d=im2bw(c);
imshow(d);

RGB component
a=imread('flowers.tif');
subplot(2,2,1);
imshow(a);
R=a;
G=a;
B=a;
R(:,:,2:3)=0;
subplot(2,2,2);
imshow(R);
G(:,:,1)=0;
G(:,:,3)=0;
subplot(2,2,3);
imshow(G);
B(:,:,1)=0;
B(:,:,2)=0;
subplot(2,2,4);
imshow(B);


Convert Image into One dimensional

a = imread('cameraman.tif');

[r c]=size(a);

Len=r*c;

b=reshape(a,[1 Len]);


CONVER MOVIE TO FRAMES
file=aviinfo('movie1.avi'); % to get inforamtaion abt video file
frm_cnt=file.NumFrames % No.of frames in the video file
str2='.bmp'
h = waitbar(0,'Please wait...');
for i=1:frm_cnt
frm(i)=aviread(filename,i); % read the Video file
frm_name=frame2im(frm(i)); % Convert Frame to image file
frm_name=rgb2gray(frm_name);%convert gray
filename1=strcat(strcat(num2str(i)),str2);
imwrite(frm_name,filename1); % Write image file
waitbar(i/frm_cnt,h)
end
close(h)


CONVERT FRAMES TO MOVIES
frm_cnt=5;
number_of_frames=frm_cnt;
filetype='.bmp';
display_time_of_frame=1;
mov = avifile('MOVIE.avi');
count=0;
for i=1:number_of_frames
name1=strcat(num2str(i),filetype);
a=imread(name1);
while count<display_time_of_frame
count=count+1;
imshow(a);
F=getframe(gca);
mov=addframe(mov,F);
end
count=0;
end
mov=close(mov);


How to read a text file
fid = fopen('message.txt','r');
ice1= fread(fid);
s = char(ice1');
fclose(fid);
disp(s);

Ans hello


How to write a text file

txt=[65 67 68 69];
fid = fopen('output.txt','wb');
fwrite(fid,char(txt),'char');
fclose(fid);

ANS =ACDE


Store an Image,Audio
a =imread('cameraman.tif');
imwrite(a,'new.bmp');

a=wavread('test.wav');
wavwrite(d,44100,16,'nTEST.WAV');


SAVE AND LOAD THE VARIABLE
A=5;
save A A;

load A

B=1;
C=A+B;
disp(C);

Wavelet transform


[LL LH HL HH]=dwt2(a,'haar');

Dec=[...
LL,LH
HL,HH
...
];

imshow(Dec,[]);


DCT transform

a=imread('cameraman.tif');
subplot(1,3,1);imshow(a,[]);
b=dct2(a);
subplot(1,3,2);imshow(b,[]);title('DCT');
c=idct2(b);
subplot(1,3,3);imshow(c,[]);title('IDCT');


NOISE AND FILTER

I = imread('eight.tif');
J = imnoise(I,'salt & pepper',0.02);
K = medfilt2(J);
subplot(1,2,1);imshow(J)
subplot(1,2,2);imshow(K)


GUI


DIALOG BOX

warndlg('hello'); helpdlg('hello'); errordlg('hello');

msgbox('hello');


ButtonName=questdlg('What is your wish?', ...
'Genie Question', ...
'Food','Clothing','Money','Money');

switch ButtonName,
case 'Food',
disp('Food is delivered');
case 'Clothing',
disp('The Emperor''s new clothes have arrived.')
case 'Money',
disp('A ton of money falls out the sky.');
end % switch


USER INTERFACE GET FILE
[filename, pathname] = uigetfile('*.m', 'Pick an M-file');
if isequal(filename,0) | isequal(pathname,0)
disp('User pressed cancel')
else
disp(['User selected ', fullfile(pathname, filename)])
end


USER INTERFACE PUT FILE
[filename, pathname] = uiputfile('*.m', 'Pick an M-file');
disp('User pressed cancel')
else
disp(['User selected ', fullfile(pathname, filename)])
end


GUI…


MENU BAR


PUSH BUTTON


TOGGLE BUTTON


RADIO BUTTON


CHECKBOX


EDIT TEXT


STATIC TEXT


SLIDER


FRAME


LISTBOX


POPUP MENU


AXES


ALIGN OBJECTS


MENU EDITOR


M FILE EDITOR


PROPERTY INSPECTOR


RUN


EMPTY GUI


GENERATED M FILE


RIGHT CLICK PUSH BUTTON & GO
FOR PROPERTY INSPECTOR


CHANGE THE STRING AND TAG
VALUE


RIGHT CLICK PUSH BUTTON & GO
FOR M FILE EDITOR


GO FOR CALLBACK


WRITE THE CODE BELOW THE
CALLBACK

imshow(a);


RUN THE PROGRAM OR PRESS F5


CHOOSE AXES


RIGHT CLICK AXES & GO FOR
PROPERTY INSPECTOR


CALLBACK
axes(handles.one);

imshow(a);


RUN THE PROGRAM


CODE


axes(handles.one);

imshow(a);


RIGHT CLICK TOGGLE & GO FOR
PROPERTY INSPECTOR


RIGHT CLICK TOGGLE & GO FOR M
FILE EDITOR


CALLBACK

a=get(hObject,'Value');

if a ==1


axes(handles.one);

imshow(a);

else

a =imread('greens.jpg');

axes(handles.one);

imshow(a);

end


RIGHT CLICK RADIO BUTTON & GO


RIGHT CLICK CHECK BOX & GO
FOR MFILE EDITOR


CALLBACK


FOR M FILE EDITOR


RIGHT CLICK FRAME & SEND TO
BACK


RIGHT CLICK LIST BOX & GO FOR
PROPERTY INSPECTOR


EDIT THE STRING OPTIONS


RIGHT CLICK LIST BOX & GO FOR M
FILE EDITOR


CALLBACK
contents = get(hObject,'Value')

switch contents

case 1
axes(handles.one);
imshow(a);
case 2
a =imread('flowers.tif');
axes(handles.one);
imshow(a);
case 3
a =imread('rice.tif');
axes(handles.one);
imshow(a);
otherwise
a =imread('mri.tif');
axes(handles.one);
imshow(a);

end


CHOOSE POPUPMENU


RIGHT CLICK POPUP MENU & GO


WRITE THE CODE
contents = get(hObject,'Value')

switch contents

case 1
axes(handles.one);
imshow(a);
case 2
a =imread('flowers.tif');
axes(handles.one);
imshow(a);
case 3
a =imread('rice.tif');
axes(handles.one);
imshow(a);
otherwise
a =imread('mri.tif');
axes(handles.one);
imshow(a);

end


RIGHT CLICK EDIT TEXT & GO FOR
PROPERTY INSPECTOR


EDIT STRING AND TAG


RIGHT CLICK EDIT TEXT & GO FOR
M FILE EDITOR


CALLBACK

a=get(hObject,'String') ;
b=char(a);
c=imread(b);
axes(handles.one);
imshow(c);


RIGHT CLICK STATIC TEXT & GO


CALLBACK
a=get(hObject,'String') ;
set(handles.t1,'String',a);
b=char(a);
c=imread(b);
axes(handles.one);
imshow(c);


RIGHT CLICK SLIDER & GO FOR
PROPERTY INSPECTOR


DROP TWO AXES


DROP PUSH BUTTON


CALLBACK
[filename, pathname] = uigetfile('*.bmp', 'Pick an Image');


warndlg('User pressed cancel')
else

a=imread(filename);
axes(handles.axes1);
imshow(a);
handles.filename=filename;
guidata(hObject, handles);

end


RIGHT CLICK SLIDER & GO FOR M
FILE EDITOR


RUN THE PROGRAM

a=get(hObject,'Value');
filename =handles.filename;
I = imread(filename);
J = imadd(I,50);
axes(handles.axes2);
imshow(J)


Counting the Number of Objects in
an Image
clc;
clear;
close all;
InputImage=imread('eight.tif');
subplot(2,2,1);
imshow(InputImage);title('InputImage');
BinaryImage=im2bw(InputImage);
subplot(2,2,2);
imshow(BinaryImage);
ComplementImage=imcomplement(BinaryImage);
subplot(2,2,3);
imshow(ComplementImage);
HolesClearedImage = imfill(ComplementImage,'holes');
subplot(2,2,4);
imshow(HolesClearedImage);title('HolesClearedImage');
[L,Num] = bwlabel(HolesClearedImage)

for i=1:Num
figure;
imshow(L==i);
pause(1)
end


Thresholding Based Segmentation-
Con 1
• clc;
• clear;
• close all;
• InputImage=imread('34.bmp');
• figure;
• imshow(InputImage);
• ColourSpaceConversion=rgb2hsv(InputImage);
• imshow(ColourSpaceConversion);
• %GrayScaleImage=rgb2gray(ColourSpaceConversion);
• GrayScaleImage=ColourSpaceConversion(:,:,1);
• [rows columns planes]=size(GrayScaleImage);
• BinaryMask= GrayScaleImage > 0.5;
• figure;
• imshow(BinaryMask);
• Impixelinfo
• h = waitbar(0,'Please wait...');
• SegmentedImage=[];

Cont 2
for i=1:rows
for j=1:columns
if BinaryMask(i,j) == 1
SegmentedImage(i,j,1)=InputImage(i,j,1);
else
SegmentedImage(i,j,1)=0;
end
end
waitbar(i/rows,h)
end
SegmentedImage=uint8(SegmentedImage);
figure;
imshow(SegmentedImage);
impixelinfo;


Image Fusion
clc;
clear;
close all;
M1=imread('mri.jpg');
M2=imread('ct.jpg');
subplot(2,2,1);imshow(M1);title('MRI');
subplot(2,2,2);imshow(M2);title('CT');
[R C P]=size(M1);
for i=1:R
for j=1:C
if M1(i,j)>M2(i,j)
FusedImage(i,j)=M1(i,j);
else
end
end
end


Image fusion-Cont 2
subplot(2,2,3);imshow(FusedImage);title('Max');
for i=1:R
for j=1:C
if M1(i,j)>M2(i,j)
else
end
end
end
subplot(2,2,4);imshow(FusedImage);title('Min');


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