Sharpening Frequency Domain Filters MCQ [Free PDF] - Objective Question Answer for Sharpening Frequency Domain Filters Quiz

1. If the Gaussian filter is expressed as H(u, v) = e^{(-D2 (u,v)/2D ₀2)}, where D(u, v) is the distance from the point(u, v), D₀ is the distance defining cutoff frequency, then for what value of D(u, v) the filter is down to 0.607 of its maximum value?

A. D(u, v) = D₀
B. D(u, v) = D₀²
C. D(u, v) = D₀³
D. D(u, v) = 0

Answer: A

For the given Gaussian filter of the 2-D image, the value D(u, v) = D₀ gives the filter down to 0.607 of its maximum value.

2. State the statement as true or false. “The GLPF did not produce as much smoothing as the BLPF of order 2 for the same value of cutoff frequency”.

A. True
B. False

Answer: A

For the same value of cutoff frequency, the GLPF did not produce as much smoothing as the BLPF of order 2, because the profile of GLPF is not as tight as the BLPF of order 2.

3. In general, which of the following assures no ringing in the output?

A. Gaussian Lowpass Filter
B. Ideal Lowpass Filter
C. Butterworth Lowpass Filter
D. All of the mentioned

Answer: A

Using Gaussian Lowpass Filter no ringing is assured, but Ideal Lowpass Filter and Butterworth Lowpass Filter of order 2and more produce significant ringing.

4. The lowpass filtering process can be applied in which of the following area(s)?

A. The field of machine perception, with the application of character recognition
B. In the field of printing and publishing industry
C. In the field of processing satellite and aerial images
D. All of the mentioned

Answer: D

The lowpass filtering process can be applied in

The field of machine perception, with the application of character recognition
In the field of printing and publishing industry
In the field of processing satellite and aerial images

In case of broken characters recognition system, LPF is used. LPF is used as a preprocessing system in the printing and publishing industry, and in the case of remotely sensed images, LPF is used to blur out as much detail as possible leaving the large feature recognizable.

5. The edges and other abrupt changes in the gray level of an image are associated with _________

A. High-frequency components
B. Low-frequency components
C. Edges with high frequency and other abrupt changes in gray-level with low-frequency components
D. Edges with low frequency and other abrupt changes in gray-level with high-frequency components

Answer: A

The edges and other abrupt changes in the gray level of an image are associated with High-frequency components.

High-frequency components are related to the edges and other abrupt changes in the gray level of an image.

6. A type of Image is called a VHRR image. What is the definition of a VHRR image?

A. Very High Range Resolution image
B. Very High-Resolution Range image
C. Very High-Resolution Radiometer image
D. Very High Range Radiometer Image

Answer: C

A VHRR image is a Very High-Resolution Radiometer Image. The NOAA Very High-Resolution Radiometer ( VHRR ) images were analyzed for mesoscale variations in sea-surface temperature at the shelf break in the region of interest.

7. The Image sharpening in the frequency domain can be achieved by which of the following method(s)?

A. Attenuating the high-frequency components
B. Attenuating the low-frequency components
C. All of the mentioned
D. None of the mentioned

Answer: B

The Image sharpening in the frequency domain is achieved by attenuating the low-frequency components without disturbing the high-frequency components.

8. The function of filters in Image sharpening in the frequency domain is to perform a reverse operation of which of the following Lowpass filter?

A. Gaussian Lowpass filter
B. Butterworth Lowpass filter
C. Ideal Lowpass filter
D. None of the Mentioned

Answer: C

The function of filters in Image sharpening in the frequency domain is to perform precisely reverse operation of the Ideal Lowpass filter.
The transfer function of Highpass filter is obtained by relation:

H_hp(u, v) = 1 – H_lp(u, v)

where H_lp(u, v) is transfer function of corresponding lowpass filter.

9. If D₀ is the cutoff distance measured from the origin of the frequency rectangle and D(u, v) is the distance from the point(u, v). Then what value will an Ideal Highpass filter give if D(u, v) ≤ D0 and if D(u, v) >D0?

A. 0 and 1 respectively
B. 1 and 0 respectively
C. 1 in both case
D. 0 in both case

Answer: A

Unlike an Ideal lowpass filter, an Ideal highpass filter attenuates the low-frequency components and so gives 0 for D(u, v) ≤ D₀ and 1 for D(u, v) >D₀.

10. What is the relation of the frequencies to a circle of radius D₀, where D₀ is the cutoff distance measured from the origin of the frequency rectangle, for an Ideal Highpass filter?

A. IHPF sets all frequencies inside the circle to zero
B. IHPF allows all frequencies, without attenuating, outside the circle
C. Both 1 and 2
D. None of the mentioned

Answer: C

The relation of the frequencies to a circle of radius D₀are

IHPF sets all frequencies inside the circle to zero
IHPF allows all frequencies, without attenuating, outside the circle

An Ideal high pass filter gives 0 for D(u, v) ≤ D₀ and 1 for D(u, v) >D₀.

11. For a given image having smaller objects, which of the following filter(s), having D₀ as the cutoff distance measured from the origin of the frequency rectangle, would you prefer for a comparably smoother result?

A. IHLF with D₀ 15
B. BHPF with D₀ 15 and order 2
C. GHPF with D₀ 15 and order 2
D. All of the mentioned

Answer: C

For the same format as for BHPF, GHPF gives a result comparably smoother than BHPF. However, BHPF’s performance for filtering smaller objects is comparable with IHPF.

12. Which of the following statement(s) is true for the given fact that “Applying Highpass filters affect the background of the output image”?

A. The average background intensity increases to near white
B. The average background intensity reduces to near black
C. The average background intensity changes to a value average of black and white
D. All of the mentioned

Answer: B

The Highpass filter eliminates the zero-frequency components of the Fourier transformed image HPFs are applied on. So, the average background intensity reduces to near black.

12. Which of the following is the transfer function of the Butterworth Highpass Filter, of order n, D0 is the cutoff distance measured from the origin of the frequency rectangle and D(u, v) is the distance from the point(u, v)?

A. $H(u,v) = \frac{1}{{1 + {{[{D_o}/D(u,v)]}^{2n}}}}$

B. $H(u,v) = \left\{ \begin{array}{l} 0{\text{ if D(u,v) }} \le {\text{ 0}}\\1{\text{ if D(u,v) }} \ge {\text{ 0}}\end{array} \right\}$

C. H(u,v) = 1 − e−D²(u,v)/2D²_o

D. None of the above

Answer: A

The transfer function of Butterworth highpass filter of order n, D0 is the cutoff distance measured from origin of frequency rectangle and D(u, v) is the distance from point(u, v) is given by

$H(u,v) = \frac{1}{{1 + {{[{D_o}/D(u,v)]}^{2n}}}}$

13. Which of the following is the transfer function of the Ideal Highpass Filter? Given that D0 is the cutoff distance measured from the origin of the frequency rectangle and D(u, v) is the distance from the point(u, v)?

A. $H(u,v) = \frac{1}{{1 + {{[{D_o}/D(u,v)]}^{2n}}}}$

B. $H(u,v) = \left\{ \begin{array}{l} 0{\text{ if D(u,v) }} \le {\text{ 0}}\\1{\text{ if D(u,v) }} \ge {\text{ 0}}\end{array} \right\}$

C. H(u,v) = 1 − e−D²(u,v)/2D²_o

D. None of the above

Answer: B

The transfer function of Ideal highpass filter, whereD0 is the cutoff distance measured from origin of frequency rectangle and D(u, v) is the distance from point(u, v) is given by:

$H(u,v) = \left\{ \begin{array}{l} 0{\text{ if D(u,v) }} \le {\text{ 0}}\\1{\text{ if D(u,v) }} \ge {\text{ 0}}\end{array} \right\}$

14. Which of the following is the transfer function of the Gaussian Highpass Filter? Given that D0 is the cutoff distance measured from the origin of the frequency rectangle and D(u, v) is the distance from the point(u, v)?

A. $H(u,v) = \frac{1}{{1 + {{[{D_o}/D(u,v)]}^{2n}}}}$

B. $H(u,v) = \left\{ \begin{array}{l} 0{\text{ if D(u,v) }} \le {\text{ 0}}\\1{\text{ if D(u,v) }} \ge {\text{ 0}}\end{array} \right\}$

C. H(u,v) = 1 − e−D²(u,v)/2D²_o

D. None of the above

Answer: C

The transfer function of the Gaussian highpass filter, where D0 is the cutoff distance measured from the origin of the frequency rectangle and D(u, v) is the distance from the point(u, v) is given by

H(u,v) = 1 − e−D²(u,v)/2D²_o

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