1. Noise reduction is obtained by blurring the image using a smoothing filter.
A. True
B. False
2. What is the output of a smoothing, linear spatial filter?
A. Median of pixels
B. Maximum of pixels
C. Minimum of pixels
D. Average of pixels
Answer: D
The output or response of smoothing, the linear spatial filter is simply the average of the pixels contained in the neighborhood of the filter mask. [/bg_collapse]
3. Smoothing linear filter is also known as a median filter.
A. True
B. False
Answer: B
Since the smoothing spatial filter performs the average of the pixels, it is also called an averaging filter. [/bg_collapse]
4. Which of the following in an image can be removed by using a smoothing filter?
A. Smooth transitions of gray levels
B. Smooth transitions of brightness levels
C. Sharp transitions of gray levels
D. Sharp transitions of brightness levels
Answer: C
The smoothing filter replaces the value of every pixel in an image with the average value of the gray levels. So, this helps in removing the sharp transitions in the gray levels between the pixels. This is done because random noise typically consists of sharp transitions in gray levels. [/bg_collapse]
5. Which of the following is the disadvantage of using a smoothing filter?
A. Blur edges
B. Blur inner pixels
C. Remove sharp transitions
D. Sharp edges
6. Smoothing spatial filters doesn’t smooth the false contours.
A. True
B. False
Answer: B
One of the applications of smoothing spatial filters is that they help in smoothing the false contours that result from using an insufficient number of gray levels. [/bg_collapse]
7. The mask shown in the figure below belongs to which type of filter?
A. Sharpening spatial filter
B. Median filter
C. Sharpening frequency filter
D. Smoothing spatial filter
Answer: D
This is a smoothing spatial filter. This mask yields a so-called weighted average, which means that different pixels are multiplied with different coefficient values. This helps in giving much importance to some pixels at the expense of others. [/bg_collapse]
8. The mask shown in the figure below belongs to which type of filter?
A. Sharpening spatial filter
B. Median filter
C. Smoothing spatial filter
D. Sharpening frequency filter
Answer: C
The mask shown in the figure represents a 3×3 smoothing filter. The use of this filter yields the standard average of the pixels under the mask. [/bg_collapse]
9. Box filter is a type of smoothing filter.
A. True
B. False
10. If the size of the averaging filter used to smooth the original image to the first image is 9, then what would be the size of the averaging filter used in smoothing the same original picture to the second in the second image?
A. 3
B. 5
C. 9
D. 15
Answer: D
We know that as the size of the filter used in smoothening the original image that is averaging filter increases then the blurring of the image. Since the second image is more blurred than the first image, the window size should be more than 9. [/bg_collapse]