Digital image processing

1. DIGITAL IMAGE
PROCESSING
CONNECTED
COMPONENT LABELING
ALGORITHM
Processing of Images which are Digital in nature by
means of Digital Computer
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2. Connected Component Labeling
 Ability to assign different labels to various
disjoint component of an image is called
connected component labeling.
 This labeling is a fundamental step in
automated image analysis:
a) Shape
b) Area
c) Boundary
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3. Basic Scanning Method
 Scan the image from left to right and top to
bottom.
 Assume 4-adjacency.
 Let p be a pixel at any step in the scanning
process.
 Before p the pixel r and t are scanned.
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r
t p

4. Labeling Algorithm
 This algorithm makes two passes over the image:
1. The first pass to assign temporary labels and
record equivalence classes.
2. The second pass to replace each temporary
label by the smallest label of its equivalence
class.
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5. Steps in First Pass
Conditions to check:
1. Does the pixel to the left (West) have the same value as
the current pixel?
Yes – We are in the same region. Assign the same
label to the current pixel
No – Check next condition
2. Do both pixels to the North and West of the current pixel
have the same value as the current pixel but not the same
label?
Yes –Assign the current pixel the minimum of the
North and West labels, and record their
equivalence relationship
No – Check next condition
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6. Steps in First Pass..
3. Does the pixel to the left (West) have a different
value and the one to the North the same value
as the current pixel?
Yes – Assign the label of the North pixel to
the current pixel
No – Check next condition
4. Do the pixel's North and West neighbors have
different pixel values than current pixel?
Yes – Create a new label id and assign it to
the current pixel
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7. Steps in Second Pass
 In the First pass we record some equivalence
relationships.
 In Second Pass:
1. Process Equivalence pairs to form
equivalent classes.
2. Re-label the element with the label
assigned to its equivalent classes.
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1

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1 2

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1 2
1

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1 2
1 2

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1 2
1 2 3

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1 2
1 2 3 3

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1 2
1 2 3 3
1

16. CENTURION INSTITUTE OF TECHNOLOGY, JATNI 16
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1 2
1 2 3 3
1 1

17. CENTURION INSTITUTE OF TECHNOLOGY, JATNI 17
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1 2
1 2 3 3
1 1 1

18. CENTURION INSTITUTE OF TECHNOLOGY, JATNI 18
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1 2
1 2 3 3
1 1 1 1 (1,2) equivalent
relation

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1 2
1 2 3 3
1 1 1 1 4

20. CENTURION INSTITUTE OF TECHNOLOGY, JATNI 20
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1 2
1 2 3 3
1 1 1 1 4 3 (3,4) equivalent
relation

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1 2
1 2 3 3
1 1 1 1 4 3 3

22. CENTURION INSTITUTE OF TECHNOLOGY, JATNI 22
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1 2
1 2 3 3
1 1 1 1 4 3 3 3

23. CENTURION INSTITUTE OF TECHNOLOGY, JATNI 23
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1 2
1 2 3 3
1 1 1 1 4 3 3 3
1

24. CENTURION INSTITUTE OF TECHNOLOGY, JATNI 24
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1 2
1 2 3 3
1 1 1 1 4 3 3 3
1 1

25. CENTURION INSTITUTE OF TECHNOLOGY, JATNI 25
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1 2
1 2 3 3
1 1 1 1 4 3 3 3
1 1 3

26. CENTURION INSTITUTE OF TECHNOLOGY, JATNI 26
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1 2
1 2 3 3
1 1 1 1 4 3 3 3
1 1 3 3

27. CENTURION INSTITUTE OF TECHNOLOGY, JATNI 27
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1 2
1 2 3 3
1 1 1 1 4 3 3 3
1 1 3 3
5

28. CENTURION INSTITUTE OF TECHNOLOGY, JATNI 28
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1 2
1 2 3 3
1 1 1 1 4 3 3 3
1 1 3 3
5 1 (1,5) equivalent
relation

29. CENTURION INSTITUTE OF TECHNOLOGY, JATNI 29
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1 2
1 2 3 3
1 1 1 1 4 3 3 3
1 1 3 3
5 1 3

30. CENTURION INSTITUTE OF TECHNOLOGY, JATNI 30
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1 2
1 2 3 3
1 1 1 1 4 3 3 3
1 1 3 3
5 1 3 3

31. CENTURION INSTITUTE OF TECHNOLOGY, JATNI 31
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1 2
1 2 3 3
1 1 1 1 4 3 3 3
1 1 3 3
5 1 3 3 3

32. CENTURION INSTITUTE OF TECHNOLOGY, JATNI 32
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1 2
1 2 3 3
1 1 1 1 4 3 3 3
1 1 3 3
5 1 3 3 3
5

33. CENTURION INSTITUTE OF TECHNOLOGY, JATNI 33
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1 1
1 2 3 3
1 1 1 1 4 3 3 3
1 1 3 3
5 1 3 3 3
5
1<= 1,2,5

34. CENTURION INSTITUTE OF TECHNOLOGY, JATNI 34
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1 1
1 1 3 3
1 1 1 1 4 3 3 3
1 1 3 3
5 1 3 3 3
5
1<= 1,2,5

35. CENTURION INSTITUTE OF TECHNOLOGY, JATNI 35
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1 1
1 1 3 3
1 1 1 1 3 3 3 3
1 1 3 3
5 1 3 3 3
5
3<= 3,4

36. CENTURION INSTITUTE OF TECHNOLOGY, JATNI 36
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1 1
1 1 3 3
1 1 1 1 3 3 3 3
1 1 3 3
1 1 3 3 3
5
1<= 1,2,5

37. CENTURION INSTITUTE OF TECHNOLOGY, JATNI 37
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1 1
1 1 3 3
1 1 1 1 3 3 3 3
1 1 3 3
1 1 3 3 3
1 1<= 1,2,5

38. CENTURION INSTITUTE OF TECHNOLOGY, JATNI 38
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1 1
1 1 3 3
1 1 1 1 3 3 3 3
1 1 3 3
1 1 3 3 3
1
Here we observed that the image contain two distinct class of regions