Mathematics in Everyday Life by Gilad Lerman Department of Mathematics University of MinnesotaGilad Lerman Department of Mathematics University of Minnesota

1. Mathematics in Everyday Life
Gilad Lerman
Department of Mathematics
University of Minnesota
Highland park elementary (6th graders)

2. What do mathematicians do?What homework do I give
my students?
• Example of a recent homework: Denoising

3. What do mathematicians do?What projects do I assign
my students?
• Example of a recent project:
Recognizing Panoramas
• Panorama:
• How to obtain a panorama?
wide view of a physical space

4. How to obtain a panorama
1. By “rotating line camera”
2. Stitching together multiple images
Your camera can do it this way…
E.g. PhotoStitch (Canon PowerShot SD600)

5. Experiment with PhotoStitch
Experiment done by Rebecca Szarkowski
Input: 10 images along a bridge

6. Experiment continued…
Experiment done by Rebecca Szarkowski
Output: Panorama (PhotoStitch)
Output: Panorama (by a more careful mathematical algorithm)

7. What’s math got to do with it?
From visual images to numbers (or digital images)
New Topic: Relation of Imaging
and Mathematics

8. Digital Image Acquisition

9. From Numbers to Images
Let us type the following numbers
1 1 1 1 1 1 1 1
2 2 2 2 2 2 2 2
3 3 3 3 3 3 3 3
4 4 4 4 4 4 4 4
5 5 5 5 5 5 5 5
6 6 6 6 6 6 6 6
7 7 7 7 7 7 7 7
8 8 8 8 8 8 8 8
We then color them so 1=black, 8=white
rest of colors are in between

10. One more time…
Now we’ll try the following numbers
1 1 1 1 1 1 1 1
2 2 2 2 2 2 2 2
4 4 4 4 4 4 4 4
8 8 8 8 8 8 8 8
16 16 16 16 16 16 16 16
32 32 32 32 32 32 32 32
64 64 64 64 64 64 64 64
128 128 128 128 128 128 128 128
We then color them so 1=black, 128=white
rest of colors are in between

11. Let’s compare
1 1 1 1 1 1 1 1
2 2 2 2 2 2 2 2
3 3 3 3 3 3 3 3
4 4 4 4 4 4 4 4
5 5 5 5 5 5 5 5
6 6 6 6 6 6 6 6
7 7 7 7 7 7 7 7
8 8 8 8 8 8 8 8
1 1 1 1 1 1 1 1
2 2 2 2 2 2 2 2
4 4 4 4 4 4 4 4
8 8 8 8 8 8 8 8
16 16 16 16 16 16 16 16
32 32 32 32 32 32 32 32
64 64 64 64 64 64 64 64
128 128 128 128 128 128 128 128

12. From an Image to Its Numbers
We start with clown image
It has 200*320 numbers
I can’t show you all…
Let’s zoom on eye (~40*50)

13. Image to Numbers (Continued)
We’ll zoom on middle of eye image (10*10)

14. The Numbers (Continued)
The middle of eye image (10*10)
80 81 80 80 80 80 77 77 37 11
81 80 81 80 80 80 77 37 9 6
80 80 80 80 80 80 37 11 2 11
80 80 80 80 80 77 66 66 66 54
80 80 80 80 77 77 77 80 77 80
80 80 79 77 66 54 66 77 66 54
77 80 77 70 22 57 51 70 51 70
77 73 70 22 2 2 22 37 37 22
77 77 54 37 1 6 2 8 2 6
77 70 70 22 2 2 6 8 8 6
Note the rule:
Bright colors – high numbers
Dark colors - low numbers

15. More Relation of Imaging and Math
Averaging numbers  smoothing images
Idea of averaging:
take an image
Replace each point by
average with its neighbors
For example, 2 has the neighborhood
So replace 2 by
80 81 80 80 80 80 77 77 37 11
81 80 81 80 80 80 77 37 9 6
80 80 80 80 80 80 37 11 2 11
80 80 80 80 80 77 66 66 66 54
80 80 80 80 77 77 77 80 77 80
80 80 79 77 66 54 66 77 66 54
77 80 77 70 22 57 51 70 51 70
77 73 70 22 2 2 22 37 37 22
77 77 54 37 1 6 2 8 2 6
77 70 70 22 2 2 6 8 8 6
70 22 57
22 2 2
37 1 6
80 81 80 80 80 80 77 77 37 11
81 80 81 80 80 80 77 37 9 6
80 80 80 80 80 80 37 11 2 11
80 80 80 80 80 77 66 66 66 54
80 80 80 80 77 77 77 80 77 80
80 80 79 77 66 54 66 77 66 54
77 80 77 70 22 57 51 70 51 70
77 73 70 22 2 2 22 37 37 22
77 77 54 37 1 6 2 8 2 6
77 70 70 22 2 2 6 8 8 6
70+22+57+22+2+2+37+1+6 1
24
9 3
=

16. Example: Smoothing by averaging
Original image on top left
It is then averaged with neighbors
of distances 3, 5, 19, 15, 35, 45

17. Example: Smoothing by averaging
And removing wrinkles by both….

18. More Relation of Imaging and Math
Differences of numbers  sharpening images
On left image of moon
On right its edges (obtained by differences)
We can add the two to get a sharpened version of the first

19. Moon sharpening (continued)

20. Real Life Applications
• Many…
• From a Minnesota based company…
• Their main job: maintaining railroads
• Main concern: Identify cracks in railroads,
before too late…

21. How to detect damaged rails?
• Traditionally… drive along the rail (very long) and
inspect
• Very easy to miss defects (falling asleep…)
• New technology: getting pictures of rails

22. Millions of images then collected

23. How to detect Cracks?
• Human observation…
• Train a computer…
• Recall that differences detect edges…
Work done by Kyle Heuton (high school student at Saint Paul)

24. Summary
• Math is useful (beyond the grocery store)
• Images are composed of numbers
• Good math ideas  good image processing