Digital image processing using matlab (fundamentals)

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Digital Image Processing Using MATLAB®
Fundamentals
of
Matlab
Improve this with www.csie.ntnu.edu.tw/~violet/IP93/Chapter01.ppt

Image Formats
http://en.wikipedia.org/wiki/Image_formats

More Image Formats
• PPM(Portable Pixelmap) • PGM(Portable Graymap)

Displaying Images
f = imread(‘rose.tif’);
imshow(f);

Try this:
>> f = imread(“Image_Name.extension”);
>> imshow(f)
>> impixelinfo
>> size(f)
ans =
1024 1024
>> [M,N] = size(f);
>> whos f
Name Size Bytes Class Attributes
r 1024x1024 1048576 uint8
Displaying Images Info.

imfinfo (bubbles.jpg)
ans =
Filename: 'bubble.jpg'
FileModDate: '14-Jan-2008 17:08:08'
FileSize: 7904
Format: 'jpg'
FormatVersion: ‘ '
Width: 720
Height: 688
BitDepth: 8
ColorType: 'grayscale'
FormatSignature: ‘ '
NumberOfSamples: 1
CodingMethod: 'Huffman'
CodingProcess: 'Sequential'
Comment: {}
Displaying Images Info.
Try this
>> K imfinfo('bubbles.jpg');
>> K.FileSize
ans =
7904

Syntax:
variable=imread(“Image_name.extension’);
Imwrite(variable,”Name.ext”);
Try This:
Step1:Read
>> b = imread(‘bubbles.tif’);
Step2:Write
>> imwrite(b,'bubbles.png');
>> imwrite(b,'bubbles.jpg');
>> imwrite(b,'bubbles', 'jpg');
Writing Images

Data Classes

Converting Between
Data Classes
Example: Suppose
A is an array of class uint8
C is an array of class double
B = double(A)
D = uint8(C)
Syntax: B = data_class_name(A)

Converting Between
Image Classes & Types

Converting Between
Image Classes & Types
Example: Consider the following 2 X 2 image f of class double:
Try This:
>> f = [-0.5 0.5; 0.75 1.5]
f =
-0.5 0.5
0.75 1.5
>> g = im2uint8(f)
g =
0 128
191 255
>> h = uint8([25 50; 128 200]);
>> g = im2double(h);
g =
0.0980 0.1961
0.4706 0.7843

Array Indexing
Example:
>> v = [1 3 5 7 9]
v =
1 3 5 7 9
>> v(2) “2nd
index”
ans =
3
>> v(2:4) “2nd
to 4th
index”
ans =
3 5 7
Guess the output of: v(3:end) v(1:2:end) v(end:-2:1)

Matrix Indexing
Example:
>> A = [1 2 3; 4 5 6; 7 8 9]
A =
1 2 3
4 5 6
7 8 9
>> A(2, 3)
ans =
6
>> R2 = A(2, :)
R2 =
4 5 6
Guess the output of: A(1:2, 1:3) A(end, end-2) A(:, 3)
Try this:
C3 = A(:, 3)
C3 =
3
6
9

Standard Arrays
>> A = 5*ones(3, 3)
A =
5 5 5
5 5 5
5 5 5
>> magic(3)
ans =
8 1 6
3 5 7
4 9 2
>> B = rand(2, 4)
B =
0.2311 0.4860 0.7621 0.0185
0.6068 0.8913 0.4565 0.8214

Operators
Example:
f =
1 2
3 4
>> v = f(:) “All column in to one column”
v =
1
3
2
4

Arithmetic Operations
Example:
>> imshow(imcomplement(f))

Relational Operators
Example:
>> A = [1 2; 3 4]
A =
1 2
3 4
>> B = [0 2; 3 5;]
B =
0 2
3 5
>> A>=B
ans =
1 1
1 0

Logical Operators and Functions

Flow Control Statements

Digital image processing using matlab (fundamentals)

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