Basic Grey Level Transformation MCQ [Free PDF] – Objective Question Answer for Basic Grey Level Transformation Quiz

11. The power-law transformation is given as s = crᵞ, c and ᵞ are positive constants, and r is the gray level of the image before processing and s after processing. Then, for what value of c and ᵞ does power-law transformation becomes identity transformation?

A. c = 1 and ᵞ < 1
B. c = 1 and ᵞ > 1
C. c = -1 and ᵞ = 0
D. c = ᵞ = 1

Answer: D

For c = ᵞ = 1 the power-law transformations s = crᵞ become s = r that is an identity transformations.

 

12. What is gamma correction?

A. A process to remove power-law transformation response phenomena
B. A process to remove log transformation response phenomena
C. A process to correct log transformation response phenomena
D. A process to correct power-law transformation response phenomena

Answer: D

The exponent used in power-law transformation is called gamma. So, using the ᵞ value, either ᵞ < 1 or ᵞ> 1, various responses are obtained.

 

13. Which of the following transformation is used in cathode ray tube (CRT) devices?

A. Log transformations
B. Power-law transformations
C. Negative transformations
D. None of the mentioned

Answer: B

The CRT devices have a power function relation between intensity and volt response. In such devices output appears darker than input. So, gamma correction is a must in this case.

 

14. Log transformation is generally used in which of the following device(s)?

A. Cathode ray tube
B. Scanners and printers
C. All of the mentioned
D. None of the mentioned

Answer: D

All the mentioned devices use gamma correction and so power-law transformation is generally of use in such cases.

 

15. The power-law transformation is given as s = crᵞ, c and ᵞ are positive constants, and r is the gray level of the image before processing and s after processing. What happens if we increase the gamma value from 0.3 to 0.7?

A. The contrast increases and the detail increases
B. The contrast decreases and the detail decreases
C. The contrast increases and the detail decreases
D. The contrast decreases and the detail increases

Answer: C

In power-law transformation, as gamma decreases are increases in image details however, the contrast reduces.

 

16. If h(rk) = nk, rk the kth gray level and nk total pixels with gray level rk, is a histogram in the gray level range [0, L – 1]. Then how can we normalize a histogram?

A. If each value of the histogram is added by the total number of pixels in the image, say n, p(RK)=nk+n
B. If each value of the histogram is subtracted by the total number of pixels in the image, say n, p(rk)=nk-n
C. If each value of the histogram is multiplied by the total number of pixels in the image, say n, p(rk)=nk * n
D. If each value of the histogram is divided by the total number of pixels in the image, say n, p(rk)=nk / n

Answer: D

To normalize a histogram each of its values is divided by a total number of pixels in the image, say n. p(rk) = nk / n.

 

17. What is the sum of all components of a normalized histogram?

A. 1
B. -1
C. 0
D. None of the mentioned

Answer: A

A normalized histogram. p(rk) = nk / n
Where n is the total number of pixels in the image, rk is the kth gray level and nk total pixels with gray level rk.
Here, p(rk) gives the probability of occurrence of rk.

 

18. A low contrast image will have what kind of histogram when, the histogram, h(rk) = nk, rk the kth gray level and nk total pixels with gray level rk, is plotted nk versus rk?

A. The histogram that is concentrated on the dark side of the grayscale
B. The histogram whose components are biased toward the high side of the grayscale
C. The histogram that is narrow and centered toward the middle of the grayscale
D. The histogram that covers a wide range of grayscale and the distribution of pixels is approximately uniform

Answer: C

The histogram plot is nk versus rk. So, the histogram of a low contrast image will be narrow and centered toward the middle of the gray scale.
A dark image will have a histogram that is concentrated on the dark side of the gray scale.

A bright image will have the histogram whose components are biased toward the high side of the gray scale.
A high contrast image will have a histogram that covers a wide range of gray scales and the distribution opixelsel is approximately uniform.

 

19. A bright image will have what kind of histogram, when the histogram, h(rk) = nk, rk the kth gray level and nk total pixels with gray level rk, is plotted nk versus rk?

A. The histogram that is concentrated on the dark side of the gray scale
B. The histogram whose components are biased toward the high side of the gray scale
C. The histogram that is narrow and centered toward the middle of the gray scale
D. The histogram that covers a wide range of gray scales and the distribution of pixels is approximately uniform

Answer: B

The histogram plot is nk versus rk. So, the histogram of a low contrast image will be narrow and centered toward the middle of the gray scale.
A dark image will have a histogram that is concentrated on the dark side of the gray scale.

A bright image will have the histogram whose components are biased toward the high side of the gray scale.
A high contrast image will have a histogram that covers a wide range of gray scales and the distribution of pixels is approximately uniform.

 

20. A high contrast image and a dark image will have what kind of histogram respectively, when the histogram, h(rk) = nk, rk the kth gray level and nk total pixels with gray level rk, is plotted nk versus rk?
The histogram is concentrated on the dark side of the gray scale.
The histogram whose components are biased toward the high side of the gray scale.
The histogram is narrow and centered toward the middle of the grayscale.
The histogram covers a wide range of grayscales and the distribution of pixels is approximately uniform.

A. I) And II) respectively
B. III) And II) respectively
C. II) And IV) respectively
D. IV) And I) respectively

Answer: D

The histogram plot is nk versus rk. So, the histogram of a low contrast image will be narrow and centered toward the middle of the gray scale.
A dark image will have a histogram that is concentrated on the dark side of the gray scale.

A bright image will have the histogram whose components are biased toward the high side of the gray scale.

A high contrast image will have a histogram that covers a wide range of gray scales and the distribution of pixels is approximately uniform.

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