image processing

1. Introduction to Image Operations
Prof. Dr. Jharna Majumdar
Prof. of Eminence, CUTM, BBSR
Ms. Sasmita Kumari Nayak
Mr. Nilamadhab Dash
CSE, CUTM, BBSR

2. Introduction to Image Operations
• Introduction to Image
• Image Operations:
– Transpose
– Flip Vertical
– Flip Horizontal
– Zoom
– Shrink
– Crop
1

3. Image
• Image is an array of pixels that are arranged in columns and
rows.
• Pixel is the fundamental component of an image.
2
Image Matrix
Image with pixel

4. Image
X
Y
X
Y
In Mathematics In Opencv
3

5. Transpose of an Image
• The transpose image B (M X N) of A (N X M) can be obtained as:
Where,
(i = 0,……..,N - 1; j = 0,……..,M - 1).
   
, ,
B j i A i j

4

6. Transpose
Input Image Transpose Image 5

7. Transpose
Input Image Transpose Image
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8. Flip Vertical
• Image B (N X M) is the vertical flip of Image A (N X M) :
Where,
(i = 0,……..,N - 1; j = 0,……..,M - 1).
   
, 1 ,
B i M j A i j
  
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9. Flip Vertical
Input Image Flip Vertical Image
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10. Flip Horizontal
• Image B (N X M) is the Horizontal flip of Image A (N X M) :
Where,
(i = 0,……..,N - 1; j = 0,……..,M - 1).
   
1 , ,
B N i j A i j
  
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11. Flip Horizontal
Input Image Flip Horizontal Image
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12. Zoom
• Increasing the number of pixels from an image.
Method 1: Replicating each row and each column a number of
times
• Two Methods:
– Nearest Neighbor Interpolation
– Bilinear Interpolation
Method 2: Replicating each pixel a number of times
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13. Nearest Neighbor
Interpolation
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14. Bilinear Interpolation
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15. Methods Zooming
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• Magnification of an image is done by replicating each pixel a number
of times.

16. Zoom
Input Image Zoom Image 15

17. Shrink
• Reduction of pixels from an image.
• Method 1: Deleting row and columns
• Method 2: Averaging pixel
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Method 1: Deleting row and columns

18. Shrink
Method 2: Averaging pixel
– Reduction of an image is done by averaging several pixels (4
adjacent pixels)
10 20 30 40
20 10 30 20
20 30 40 10
10 20 10 40
pixel averaging
=> x 1/2
15 30
20 25
Example of reduction by selecting every second pixel
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19. Shrink
Input Image Shrink Image 18

20. Crop
• A region of interest is the part of the image which we want
to process separately
• The cropped image B (N1, N2) of A (N X M), starting from
(n1, n2) can be obtained as:
• For (k = 0,…….,N1-1, l= 0,………,N2-1)
   
1 1
, ,
B k l A k l
N N
  
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21. Crop
Input Image Crop Image 20