Digital image processing
Examination 2
1. Calculate the value of the center pixel (gray background) using
2 3 4
a. Average filter
2 3 0
b. Median filter
0 2 1
c. Laplace filter, where the center coefficient is 8
d. Laplace filter, where the center coefficient is –4
e. If the original pixel values are of UINT-type, what kind of problems may
arise with filtering ?
Present how you calculated you answer, not just the final result.
(1p each)
2. Here you see a frequency domain presentation of an image.
a.
b.
c.
d.
e.
How are the frequencies organized ? Where is the zero frequency ?
What does the zero frequency tells us about the spatial domain image ?
How do you obtain ideal low pass filtering ?
How do you obtain gaussian high pass filtering ?
What is the essential difference between ideal, Butterworth and Gaussian
filters ?
CONTINUES ON THE NEXT PAGE !!!
3. Color image processing. Answer briefly (1p each).
a. Why it is useful to use color images ?
b. How does human eye perceive colors ?
c. What is RGB ?
d. What is CMY ?
e. In what applications RGB and CMY are used, respectively ?
4. Explain the process of image restoration using the Fourier transform and
convolution theorem. (5p)
That’s it. Thank you for your participation in this course, have a safe trip home and good
luck for the future ☺
Jukka