# Digital Image Processing Questions and Answers – Smoothing Linear Spatial Filters

This set of Digital Image Processing Questions and Answers for Aptitude test focuses on “Smoothing Linear Spatial Filters”.

1. Smoothing filter is used for which of the following work(s)?
a) Blurring
b) Noise reduction
c) All of the mentioned
d) None of the mentioned

Explanation: Smoothing filter is used for blurring and noise reduction.

2. The response of the smoothing linear spatial filter is/are __________
a) Sum of image pixel in the neighborhood filter mask
b) Difference of image in the neighborhood filter mask
c) Product of pixel in the neighborhood filter mask
d) Average of pixels in the neighborhood of filter mask

Explanation: The average of pixels in the neighborhood of filter mask is simply the output of the smoothing linear spatial filter.

3. Which of the following filter(s) results in a value as average of pixels in the neighborhood of filter mask.
a) Smoothing linear spatial filter
b) Averaging filter
c) Lowpass filter
d) All of the mentioned

Explanation: The output as an average of pixels in the neighborhood of filter mask is simply the output of the smoothing linear spatial filter also known as averaging filter and lowpass filter.

4. What is/are the resultant image of a smoothing filter?
a) Image with high sharp transitions in gray levels
b) Image with reduced sharp transitions in gray levels
c) All of the mentioned
d) None of the mentioned

Explanation: Random noise has sharp transitions in gray levels and smoothing filters does noise reduction.

5. At which of the following scenarios averaging filters is/are used?
a) In the reduction of irrelevant details in an image
b) For smoothing of false contours
c) For noise reductions
d) All of the mentioned

Explanation: Averaging filter or smoothing linear spatial filter is used: for noise reduction by reducing the sharp transitions in gray level, for smoothing false contours that arises because of use of insufficient number of gray values and for reduction of irrelevant data i.e. the pixels regions that are small in comparison of filter mask.

6. A spatial averaging filter having all the coefficients equal is termed _________
a) A box filter
b) A weighted average filter
c) A standard average filter
d) A median filter

Explanation: An averaging filter is termed as box filter if all the coefficients of spatial averaging filter are equal.

7. What does using a mask having central coefficient maximum and then the coefficients reducing as a function of increasing distance from origin results?
a) It results in increasing blurring in smoothing process
b) It results to reduce blurring in smoothing process
c) Nothing with blurring occurs as mask coefficient relation has no effect on smoothing process
d) None of the mentioned

Explanation: Use of a mask having central coefficient maximum and then the coefficients reducing as a function of increasing distance from origin is a strategy to reduce blurring in smoothing process.

8. What is the relation between blurring effect with change in filter size?
a) Blurring increases with decrease of the size of filter size
b) Blurring decrease with decrease of the size of filter size
c) Blurring decrease with increase of the size of filter size
d) Blurring increases with increase of the size of filter size

Explanation: Using a size 3 filter 3*3 and 5*5 size squares and other objects shows a significant blurring with respect to object of larger size.
The blurring gets more pronounced while using filter size 5, 9 and so on.

Sanfoundry Global Education & Learning Series – Digital Image Processing.