PANIMALAR ENGINEERNG COLLEGE

DEPARTMENT OF ECE
EC8093 – DIGITAL IMAGE PROCESSING
Possible Multiple Choice Questions
UNIT 1 – DIGITAL IMAGE FUNDAMENTALS
1. In a digital image f(x,y), x and y denotes
a) Brightness
b) Radiance
c) Illumination
d) Spatial coordinates
Answer: d

2. An image is considered to be a function of f(x,y) = A, where A represents:

a) Height of image
b) Width of image
c) Amplitude or brightness at point (x,y)
d) Resolution of image
Answer: c

3. The smallest element of a digital image is called

a. Pel or Pixel
b. Bit
c. Byte
d. All of the above

4. The range of values spanned by the gray scale is called:

a) Dynamic range
b) Band range
c) Peak range
d) Resolution range
Answer: a

5. Which is a colour attribute that describes a pure colour?

a) Saturation
b) Hue
c) Brightness
d) Intensity
Answer: b

6. Which gives a measure of the degree to which a pure colour is diluted by white light?
a) Saturation
b) Hue
c) Intensity
d) Brightness
Answer: a.
7. The number of grey values are integer powers of:
a) 4
b) 2
c) 8
d) 1
Answer: b

8. What is the first and foremost step in Image Processing?

a) Image restoration
b) Image enhancement
c) Image acquisition
d) Segmentation
Answer: c

9. In which step of processing, the images are subdivided successively into smaller
regions?
a) Image enhancement
b) Image acquisition
c) Segmentation
d) Wavelets
Answer: d.

10. Which of the following step deals with tools for extracting image components those
are useful in the representation and description of shape?
a) Segmentation
b) Representation & description
c) Compression
d) Morphological processing
Answer: d

11. In which step of the processing, assigning a label (e.g., “vehicle”) to an object based
on its descriptors is done?
a) Object recognition
b) Morphological processing
c) Segmentation
d) Representation & description
Answer: a

12. What role does the segmentation play in image processing?

a) Deals with extracting attributes that result in some quantitative information of
interest
b) Deals with techniques for reducing the storage required saving an image, or the
bandwidth required transmitting it
c) Deals with partitioning an image into its constituent parts or objects
d) Deals with property in which images are subdivided successively into smaller
regions
Answer: c

13. To convert a continuous sensed data into Digital form, which of the following is
required?
 a) Sampling
b) Quantization
c) Both Sampling and Quantization
d) Neither Sampling nor Quantization
Answer: c

14. To convert a continuous image f(x, y) to digital form, we have to sample the function
in __________
a) Coordinates
b) Amplitude`
c) All of the mentioned
d) None of the mentioned
Answer: c

15. For a continuous image f(x, y), how could be Sampling defined?
a) Digitizing the coordinate values
b) Digitizing the amplitude values
c) All of the mentioned
d) None of the mentioned
Answer: a

16. For a continuous image f(x, y), Quantization is defined as

a) Digitizing the coordinate values
b) Digitizing the amplitude values
c) All of the mentioned
d) None of the mentioned
Answer: b

17. Validate the statement:

“For a given image in one-dimension given by function f(x, y), to sample the function
we take equally spaced samples, superimposed on the function, along a horizontal
line. However, the sample values still span (vertically) a continuous range of gray-
level values. So, to convert the given function into a digital function, the gray-level
values must be divided into various discrete levels.”
a) True
b) False
Answer: a

18. How does sampling gets accomplished with a sensing strip being used for image
acquisition?
a) The number of sensors in the strip establishes the sampling limitations in one image
direction and Mechanical motion in the other direction
b) The number of sensors in the sensing array establishes the limits of sampling in
both directions
c) The number of mechanical increments when the sensor is activated to collect data
d) None of the mentioned
Answer: a

19. The quality of a digital image is well determined by ___________

a) The number of samples
 b) The discrete gray levels
c) All of the mentioned
d) None of the mentioned
Answer: c

20. Assume that an image f(x, y) is sampled so that the result has M rows and N columns.
If the values of the coordinates at the origin are (x, y) = (0, 0), then the notation (0, 1)
is used to signify :
a) Second sample along first row
b) First sample along second row
c) First sample along first row
d) Second sample along second row
Answer: a

21. The digitization process i.e. the digital image has M rows and N columns, requires
decisions about values for M, N, and for the number, L, of gray levels allowed for
each pixel. The value M and N have to be:
a) M and N have to be positive integer
b) M and N have to be negative integer
c) M have to be negative and N have to be positive integer
d) M have to be positive and N have to be negative integer
Answer: a

22. The digitization process i.e. the digital image has M rows and N columns, requires
decisions about values for M, N, and for the number, L, of max gray levels. There are
no requirements on M and N, other than that M and N have to be positive integer.
However, the number of gray levels typically is
a) An integer power of 2 i.e. L = 2k
b) A Real power of 2 i.e. L = 2k
c) Two times the integer value i.e. L = 2k
d) None of the mentioned
Answer: a

23. The digitization process i.e. the digital image has M rows and N columns, requires
decisions about values for M, N, and for the number, L, of max gray levels is an
integer power of 2 i.e. L = 2k, allowed for each pixel. If we assume that the discrete
levels are equally spaced and that they are integers then they are in the interval
__________ and Sometimes the range of values spanned by the gray scale is called
the ________ of an image.
a) [0, L – 1] and static range respectively
b) [0, L / 2] and dynamic range respectively
c) [0, L / 2] and static range respectively
d) [0, L – 1] and dynamic range respectively
Answer: d

24. After digitization process a digital image with M rows and N columns have to be
positive and for the number, L, max gray levels i.e. an integer power of 2 for each
pixel. Then, the number b, of bits required to store a digitized image is:
a) b=M*N*k
b) b=M*N*L
 c) b=M*L*k
d) b=L*N*k
Answer: a

25. Validate the statement “When in an Image an appreciable number of pixels exhibit
high dynamic range, the image will have high contrast.”
a) True
b) False
Answer: a

26. In digital image of M rows and N columns and L discrete gray levels, calculate the
bits required to store a digitized image for M=N=32 and L=16.
a) 16384
b) 4096
c) 8192
d) 512
Answer: b
Solution: In digital image of M rows and N columns and L max gray levels i.e. an
integer power of 2 for each pixel. The number, b, of bits required to store a digitized
image is: b=M*N*k.
For L=16, k=4.
i.e. b=4096.

27. Images quantised with insufficient brightness levels will lead to the occurrence of
____________
a) Pixillation
b) Blurring
c) False Contours
d) None of the Mentioned

28. The smallest discernible change in intensity level is called ____________

a) Intensity Resolution
b) Contour
c) Saturation
d) Contrast

29. What is the tool used in tasks such as zooming, shrinking, rotating, etc.?
a) Sampling
b) Interpolation
c) Filters
d) None of the Mentioned

30. The most familiar single sensor used for Image Acquisition is
a) Microdensitometer
b) Photodiode
c) CMOS
d) None of the Mentioned

31. A geometry consisting of in-line arrangement of sensors for image acquisition

a) A photodiode
 b) Sensor strips
c) Sensor arrays
d) CMOS

32. The difference is intensity between the highest and the lowest intensity levels in an
image is ___________
a) Noise
b) Saturation
c) Contrast
d) Brightness
Answer: c

33. _____________ is the effect caused by the insufficient sampling in a digital image.
a) Gaussian smooth
b) Contouring
c) False Contouring
d) Moire Pattern

34. The process of using known data to estimate values at unknown locations is called
a) Acquisition
b) Interpolation
c) Pixelation
d) None of the Mentioned

35. Of the following, _________ has the maximum frequency.

a) UV Rays
b) Gamma Rays
c) Microwaves
d) Radio Waves

36. In the Visible spectrum the ______ colour has the maximum wavelength.
a) Violet
b) Blue
c) Red
d) Yellow
Answer: c
Explanation: Red is towards the right in the electromagnetic spectrum sorted in the
increasing order of wavelength.

37. Wavelength and frequency are related as : (c = speed of light)

a) c = wavelength / frequency
b) frequency = wavelength / c
c) wavelength = c * frequency
d) c = wavelength * frequency

38. How is radiance measured?

a) lumens
b) watts
c) armstrong
d) hertz
39. Which of the following is used for chest and dental scans?
a) Hard X-Rays
b) Soft X-Rays
c) Radio waves
d) Infrared Rays

40. Which of the following is impractical to measure?

a) Frequency
b) Radiance
c) Luminance
d) Brightness

41. What do you mean by achromatic light?

a) Chromatic light
b) Monochromatic light
c) Infrared light
d) Invisible light

42. In 4-neighbours of a pixel p, how far are each of the neighbours located from p?
a) one pixel apart
b) four pixels apart
c) alternating pixels
d) none of the Mentioned

43. If S is a subset of pixels, pixels p and q are said to be ____________ if there exists a
path between them consisting of pixels entirely in S.
a) continuous
b) ambiguous
c) connected
d) none of the Mentioned

44. If R is a subset of pixels, we call R a _________ of the image if R is a connected set.

a) Disjoint
b) Region
c) Closed
d) Adjacent

45. Two regions are said to be ___________ if their union forms a connected set.
a) Adjacent
b) Disjoint
c) Closed
d) None of the Mentioned

46. The distance between pixels p and q, the pixels have a distance less than or equal to
some value of radius r centred at (x,y) is called :
a) Euclidean distance
b) City-Block distance
 c) Chessboard distance
d) None of the Mentioned

47. The distance between pixels p and q, the pixels have a distance less than or equal to
some value of radius r, form a diamond centred at (x,y) is called :
a) Euclidean distance
b) Chessboard distance
c) City-Block distance
d) None of the Mentioned

48. The distance between pixels p and q, the pixels have a distance less than or equal to
some value of radius r, form a square centred at (x,y) is called :
a) Euclidean distance
b) Chessboard distance
c) City-Block distance
d) None of the Mentioned

49. Which of the following is NOT is not a type of Adjacency?

a) 4-Adjacency
b) 8-Adjacency
c) m-Adjacency
d) D-adjacency

50. Which of the following is a receptor in the retina of human eye?

a) fovea
b) Choroid
c) Rods and Cones
d) lens

51. The inner most membrane of the human eye is

a) Blind Spot
b) Sclera
c) Choroid
d) Retina

52. What is the function of Iris?

a) Source of nutrition
b) Detect color
c) Varies focal length
d) Control amount of light that enters eye

53. Ratio of number of rods to the number of cones is _______

a) 1:20
b) 1:2
c) 1:1
d) 1:5
Explanation: No of rods: 6 to 7 million, No of rods: 75 to 150
54. The absence of receptors is in the retinal area called _____________
a) Lens
b) Ciliary body
c) Blind spot
d) Fovea

55. Dim-light vision is otherwise known as

a)Photopic vision
b)Scotopic vision
c)Bipolar vision
d) None of the above

56. Bright light vision is otherwise known as

a. Scotopic vision
b. Photopic vision
c. Bipolar vision
d. None of the above

57. ________________ are responsible for Scotopic vision

a)Rods
b)Fovea
c)Iris
d)Cones

58. -------------------are responsible for Photopic vision

a)Rods
b)Fovea
c)Iris
d)Cones

59. What are the types of color image processing?

a) Full-color and pseudo-color processing
b) Half-color and full-color processing
c) Half-color and pseudo-color processing
d) Pseudo-color and Multi-color processing

60. What are the basic quantities that are used to describe the quality of a chromatic light
source?
a) Radiance, brightness and wavelength
b) Brightness and luminence
c) Radiance, brightness and luminence
d) Luminence and radiance

61. What is the quantity that is used to measure the total amount of energy flowing from
the light source?
a) Brightness
b) Intensity
c) Luminence
d) Radiance
62. What are the characteristics that are used to distinguish one color from the other?
a) Brightness, Hue and Saturation
b) Hue, Brightness and Intensity
c) Saturation, Hue
d) Brightness, Saturation and Intensity

63. What are the characteristics that are taken together in chromaticity?
a) Saturation and Brightness
b) Hue and Saturation
c) Hue and Brightness
d) Saturation, Hue and Brightness

64. Which of the following represent the correct equations for trichromatic coefficients?
a) x=X/(X+Y+Z), y=Y/(X+Y+Z), z=Z/(X+Y+Z)
b) x=(Y+Z)/(X+Y+Z), y=(X+Z)/(X+Y+Z), z=(X+Y)/(X+Y+Z)
c) x=X/(X-Y+Z), y=Y/(X-Y+Z), z=Z/(X-Y+Z)
d) x=(-X)/(X+Y+Z), y=(-Y)/(X+Y+Z), z=(-Z)/(X+Y+Z)

65. What do you mean by tri-stimulus values?

a) It is the amount of red, green and yellow needed to form any particular color
b) It is the amount of red, green and indigo needed to form any particular color
c) It is the amount of red, yellow and blue needed to form any particular color
d) It is the amount of red, green and blue needed to form any particular color

66. What is the value obtained by the sum of the three trichromatic coefficients?
a) 0
b)-1
c) 1
d) Null

67. What is the name of area of the triangle in C.I E chromatic diagram that shows a
typical range of colors produced by RGB monitors?
a) Color gamut
b) Tricolor
c) Color game
d) Chromatic colors

68. What do you mean by the term pixel depth?

a) It is the number of bits used to represent each pixel in RGB space
b) It is the number of bytes used to represent each pixel in RGB space
c) It is the number of units used to represent each pixel in RGB space
d) It is the number of mm used to represent each pixel in RGB space

69. How many bit RGB color image is represented by full-color image?
a) 32-bit RGB color image
b) 24-bit RGB color image
c) 16-bit RGB color image
d) 8-bit RGB color image
70. What is the equation used to obtain I(Intensity) component of each RGB pixel in RGB
color format?
a) I=1/2(R+G+B)
b) I=1/3(R+G+B)
c) I=1/3(R-G-B)
d) I=1/3(R-G+B)

71. What is the equation used for calculating B value in terms of HSI components?
a) B=I(1+S)
b) B=S(1-I)
c) B=S(1+I)
d) B=I(1-S)

72. What is the equation used for calculating G value in terms of HSI components?
a) G=3I-(R+B)
b) G=3I+(R+B)
c) G=3I-(R-B)
d) G=2I-(R+B)

73. Which of the following color models are used for color printing?
a) RGB
b) CMY
c) CMYK
d) CMY and CMYK

74. How is array operation carried out involving one or more images?
a) array by array
b) pixel by pixel
c) column by column
d) row by row

75. RGB safe color cube consists of

a) 256 colors
b) 512 colors
c) 216 colors
d) 1024 colors

76. _______________ based on the fact that Human Visual System tends to overshoot or
undershoot around the boundary of regions of different intensities.
a. Simultaneous contrast
b. Machband Effect
c. Checkerboard pattern
d. False contouring

77. HVS perceive a brightness pattern that is strongly scalloped, especially near the
boundaries. These seemingly scalloped bands are called
a. Color bands
b. Monochrome bands
c. Dichrome bands
d. Machbands
78. ________________ phenomenon is related to the fact that a region's perceived
brightness does not depend simply on its intensity. However, they appear to become
darker as the background gets lighter.
a. Simultaneous contrast
b. Machband Effect
c. Checkerboard pattern
d. False contouring

79. __________________________ are used to convert images from spatial domain to

frequency domain
a. Transforms
b. Translations
c. Subtractions
d. All of the above

80. Checkerboard pattern is caused due to reduction in

a. Gray level resolution
b. Spatial resolution
c. Misfocus of camera
d. None of the above