# Image Enhancement in Digital Image Processing MCQ [Free PDF] – Objective Question Answer for Image Enhancement in Digital Image Processing Quiz

41. Which of the following transformations is particularly well suited for enhancing an image with white and gray detail embedded in dark regions of the image, especially when there is more black area in the image.

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

Negative transformation reverses the intensity levels in the image and produces an equivalent photographic negative. So, well suited for the above-given condition.

42. Which of the following transformations expands the value of dark pixels while the higher-level values are being compressed?

A. Log transformations
B. Inverse-log transformations
C. Negative transformations
D. None of the mentioned

Log transformation derives a narrow range of gray-level values in the input image to a wider range of gray levels in the output image and does perform the above-given transformation.
The inverse-log is applied for the opposite.

43. Although power-law transformations are considered more versatile than log transformations for compressing gray levels in an image, then, how are log transformations advantageous over power-law transformations?

A. The log transformation compresses the dynamic range of images
B. The log transformations reverse the intensity levels in the images
C. All of Mentioned
D. None of the mentioned

For compressing gray levels in an image, power-law transformation is more versatile than log transformation, but log transformation has an important characteristic of compressing dynamic ranges of pixels having a large variety of values.

44. A typical Fourier Spectrum with spectrum values ranging from 0 to 106, which of the following transformation is better to apply.

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

The log transformation compresses the dynamic range of images and so the given range turns from 0 to approx. 7, which is easily displayable with the 8-bit display.

45. 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

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

46. 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

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.

47. 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

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.

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

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

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

49. 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

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

50. 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