## Digital Image Processing MCQ | Basics Of Image Sampling & Quantization

100+ MCQ’s Questions of digital Image Processing mcq question 2021 – Digital Image processing is a method to perform some operations on an image, in order to get an enhanced image or to extract some useful information from it. It is a type of signal processing in which input is an image and output may be image or characteristics/features associated with that image.

Here’s the list of chapters on the “Digital Image Processing” subject covering 100+ topics. You can practice the MCQs chapter by chapter . digital image processing mcq questions

## DIP ALL CHAPTERS

1. Basic of Digital Image Processing
2. Digital Image Fundamentals
3. Intensity Transformations and Spatial Filtering
4. Filtering in Frequency Domain
5. Image Restoration and Reconstruction
6. Color Image Processing
7. Image Compression
8. Morphological Image Processing
9. Image Segmentation
10. Representation and Description
11. Wavelet based Image Processing
12. Image Enhancement
13. Object Recognition

## 2. Digital Image Fundamentals

1. Digital Image Fundamentals
The section contains questions and answers on image sampling and quantization, image sensing and acquisition, electromagnetic spectrum, relationship between pixels, mathematical tools of digital image processing.

## TOPICS

• Basics Of Image Sampling & Quantization
• Representing Digital Images
• Image Sampling and Quantization
• Image Sensing and Acquisition
• Light and the Electromagnetic Spectrum
• Mathematical Tools in Digital Image Processing
• Basic Relationships between Pixels

## Basics Of Image Sampling & Quantization

1. 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

Explanation: The output of the most sensor is a continuous waveform and the amplitude and spatial behavior of such waveform are related to the physical phenomenon being sensed.

2. 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

Explanation: An image may be continuous in the x- and y-coordinates or in amplitude, or in both.

3. 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

Explanation: Sampling is the method of digitizing the coordinate values of the image.

4. 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

Explanation: Sampling is the method of digitizing the amplitude values of the image.

5. 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

Explanation: Digital function requires both sampling and quantization of the one-dimensional image function.

6. How is sampling been done when an image is generated by a single sensing element combined with mechanical motion?
a) The number of sensors in the strip defines the sampling limitations in one 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.

Explanation: When an image is generated by a single sensing element along with mechanical motion, the output data is quantized by dividing the gray-level scale into many discrete levels. However, sampling is done by selecting the number of individual mechanical increments recorded at which we activate the sensor to collect data.

7. 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

Explanation: When a sensing strip is used the number of sensors in the strip defines the sampling limitations in one direction and mechanical motion in the other direction.

8. How is sampling accomplished when a sensing array is 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 defines the limits of sampling in both directions
c) The number of mechanical increments at which we activate the sensor to collect data
d) None of the mentioned

Explanation: When we use sensing array for image acquisition, there is no motion and so, only the number of sensors in the array defines the limits of sampling in both directions and the output of the sensor is quantized by dividing the gray-level scale into many discrete levels.

9. 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

Explanation: The quality of a digital image is determined mostly by the number of samples and discrete gray levels used in sampling and quantization.

## Representing Digital Images

1. 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

Explanation: The values of the coordinates at the origin are (x, y) = (0, 0). Then, the next coordinate values (second sample) along the first row of the image are represented as (x, y) = (0, 1).

2. The resulting image of sampling and quantization is considered a matrix of real numbers. By what name(s) the element of this matrix array is called __________
a) Image element or Picture element
b) Pixel or Pel
c) All of the mentioned
d) None of the mentioned

Explanation: Sampling and Quantization of an image f(x, y) forms a matrix of real numbers and each element of this matrix array is commonly known as Image element or Picture element or Pixel or Pel.

3. Let Z be the set of real integers and R the set of real numbers. The sampling process may be viewed as partitioning the x-y plane into a grid, with the central coordinates of each grid being from the Cartesian product Z2, that is a set of all ordered pairs (zi, zj), with zi and zj being integers from Z. Then, f(x, y) is said a digital image if:
a) (x, y) are integers from Z2 and f is a function that assigns a gray-level value (from Z) to each distinct pair of coordinates (x, y)
b) (x, y) are integers from R2 and f is a function that assigns a gray-level value (from R) to each distinct pair of coordinates (x, y)
c) (x, y) are integers from R2 and f is a function that assigns a gray-level value (from Z) to each distinct pair of coordinates (x, y)
d) (x, y) are integers from Z2 and f is a function that assigns a gray-level value (from R) to each distinct pair of coordinates (x, y)

Explanation: In the given condition, f(x, y) is a digital image if (x, y) are integers from Z2 and f a function that assigns a gray-level value (that is, a real number from the set R) to each distinct coordinate pair (x, y).

4. Let Z be the set of real integers and R the set of real numbers. The sampling process may be viewed as partitioning the x-y plane into a grid, with the central coordinates of each grid being from the Cartesian product Z2, that is a set of all ordered pairs (zi, zj), with zi and zj being integers from Z. Then, f(x, y) is a digital image if (x, y) are integers from Z2 and f is a function that assigns a gray-level value (that is, a real number from the set R) to each distinct coordinate pair (x, y). What happens to the digital image if the gray levels also are integers?
a) The Digital image then becomes a 2-D function whose coordinates and amplitude values are integers
b) The Digital image then becomes a 1-D function whose coordinates and amplitude values are integers
c) The gray level can never be integer
d) None of the mentioned

Explanation: In Quantization Process if the gray levels also are integers the Digital image then becomes a 2-D function whose coordinates and amplitude values are integers.

5. 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

Explanation: 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 level. There are no requirements on M and N, other than that M and N have to be positive integer.

6. 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

Explanation: Due to processing, storage, and considering the sampling hardware, the number of gray levels typically is an integer power of 2 i.e. L = 2k.

7. 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

Explanation: In digitization process M rows and N columns have to be positive and for the number, L, of discrete gray levels typically an integer power of 2 for each pixel. If we assume that the discrete levels are equally spaced and that they are integers then they lie in the interval [0, L-1] and Sometimes the range of values spanned by the gray scale is called the dynamic range of an image.

8. 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

Explanation: In digital image of M rows and N columns and L max gray levels an integer power of 2 for each pixel. The number, b, of bits required to store a digitized image is: b=M*N*k.

9. An image whose gray-levels span a significant portion of gray scale have __________ dynamic range while an image with dull, washed out gray look have __________ dynamic range.
a) Low and High respectively
b) High and Low respectively
c) Both have High dynamic range, irrespective of gray levels span significance on gray scale
d) Both have Low dynamic range, irrespective of gray levels span significance on gray scale

Explanation: An image whose gray-levels signifies a large portion of gray scale have High dynamic range, while that with dull, washed out gray look have Low dynamic range.

10. 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

Explanation: In an Image if an appreciable number of pixels exhibit high dynamic range property, the image will have high contrast.

11. 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

Explanation: 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.

## Image Sampling and Quantization

1. A continuous image is digitised at _______ points.
a) random
b) vertex
c) contour
d) sampling

Explanation: The sampling points are ordered in the plane and their relation is called a Grid.

2. The transition between continuous values of the image function and its digital equivalent is called ______________
a) Quantisation
b) Sampling
c) Rasterisation
d) None of the Mentioned

Explanation: The transition between continuous values of the image function and its digital equivalent is called Quantisation.

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

Explanation: This effect arises when the number brightness levels is lower that which the human eye can distinguish.

4. The smallest discernible change in intensity level is called ____________
a) Intensity Resolution
b) Contour
c) Saturation
d) Contrast

Explanation: Number of bits used to quantize intensity of an image is called intensity resolution.

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

Explanation: Interpolation is the basic tool used for zooming, shrinking, rotating, etc.

6. The type of Interpolation where for each new location the intensity of the immediate pixel is assigned is ___________
a) bicubic interpolation
b) cubic interpolation
c) bilinear interpolation
d) nearest neighbour interpolation

Explanation: Its called as Nearest Neighbour Interpolation since for each new location the intensity of the next neighbouring pixel is assigned.

7. The type of Interpolation where the intensity of the FOUR neighbouring pixels is used to obtain intensity a new location is called ___________
a) cubic interpolation
b) nearest neighbour interpolation
c) bilinear interpolation
d) bicubic interpolation

Explanation: Bilinear interpolation is where the FOUR neighbouring pixels is used to estimate intensity for a new location.

8. Dynamic range of imaging system is a ratio where the upper limit is determined by
a) Saturation
b) Noise
c) Brightness
d) Contrast

Explanation: Saturation is taken as the Numerator.

9. For Dynamic range ratio the lower limit is determined by
a) Saturation
b) Brightness
c) Noise
d) Contrast

Explanation: Noise is taken as the Denominator.

10. Quantitatively, spatial resolution cannot be represented in which of the following ways
a) line pairs
b) pixels
c) dots
d) none of the Mentioned

Explanation: All the options can be used to represent spatial resolution.

## Image Sensing and Acquisition

Digital Image Processing Multiple Choice Questions & Answers (MCQs) focuses on “Image Sensing and Acquisition”.

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

Explanation: Photodiode is the most commonly used single sensor made up of silicon materials.

2. A geometry consisting of in-line arrangement of sensors for image acquisition
a) A photodiode
b) Sensor strips
c) Sensor arrays
d) CMOS

Explanation: Sensor strips are very common next to single sensor and use in-line arrangement.

3. CAT in imaging stands for
a) Computer Aided Telegraphy
b) Computer Aided Tomography
c) Computerised Axial Telegraphy
d) Computerised Axial Tomography

Explanation: Industrial Computerized Axial Tomography is based on image acquisition using sensor strips.

4. The section of the real plane spanned by the coordinates of an image is called the _____________
a) Spacial Domain
b) Coordinate Axes
c) Plane of Symmetry
d) None of the Mentioned

Explanation: The section of the real plane spanned by the coordinates of an image is called the Spacial Domain, with the x and y coordinates referred to as Spatial coordinates.

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

Explanation: Contrast is the measure of the difference is intensity between the highest and the lowest intensity levels in an image.

6. _____________ is the effect caused by the use of an insufficient number of intensity levels in smooth areas of a digital image.
a) Gaussian smooth
b) Contouring
c) False Contouring
d) Interpolation
Explanation: It is called so because the ridges resemble the contours of a map.

7. 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

Explanation: Interpolation is the process used to estimate unknown locations. It is applied in all image resampling methods.

8. Which of the following is NOT an application of Image Multiplication?
c) Pixelation
d) Region of Interest operations

Explanation: Because Pixelation deals with enlargement of pixels.

9. The procedure done on a digital image to alter the values of its individual pixels is
a) Neighbourhood Operations
b) Image Registration
c) Geometric Spacial Transformation
d) Single Pixel Operation

Explanation: It is expressed as a transformation function T, of the form s=T(z) , where z is the intensity.

10. In Geometric Spacial Transformation, points whose locations are known precisely in input and reference images.
a) Tie points
b) Réseau points
c) Known points
d) Key-points

Explanation: Tie points, also called Control points are points whose locations are known precisely in input and reference images.

## Light and the Electromagnetic Spectrum

1. Of the following, _________ has the maximum frequency.
a) UV Rays
b) Gamma Rays
c) Microwaves

Explanation: Gamma Rays come first in the electromagnetic spectrum sorted in the decreasing order of frequency.

2. In the Visible spectrum the ______ colour has the maximum wavelength.
a) Violet
b) Blue
c) Red
d) Yellow

Explanation: Red is towards the right in the electromagnetic spectrum sorted in the increasing order of wavelength.

3. 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

Explanation: It is usually written as wavelength = c / frequency.

4. Electromagnetic waves can be visualised as a
a) sine wave
b) cosine wave
c) tangential wave
d) None of the mentioned

Explanation: Electromagnetic waves are visualized as sinusoidal wave.

a) lumens
b) watts
c) armstrong
d) hertz

Explanation: Radiance is the total amount of energy that flows from the light source and is measured in Watts.

6. Which of the following is used for chest and dental scans?
a) Hard X-Rays
b) Soft X-Rays
d) Infrared Rays

Explanation: Soft X-Rays (low energy) are used for dental and chest scans.

7. Which of the following is impractical to measure?
a) Frequency
c) Luminance
d) Brightness

Explanation: Brightness is subjective descriptor of light perception that is impossible to measure.

8. Massless particle containing a certain amount of energy is called
a) Photon
b) Shell
c) Electron
d) None of the mentioned

Explanation: Each bundle of massless energy is called a Photon.

9. What do you mean by achromatic light?
a) Chromatic light
b) Monochromatic light
c) Infrared light
d) Invisible light

Explanation: Achromatic light is also called monochromatic light.(Light void of color)

10. Which of the following embodies the achromatic notion of intensity?
a) Luminance
b) Brightness
c) Frequency

Explanation: Brightness embodies the achromatic notion of intensity and is a key factor in describing color sensation.

## Mathematical Tools in Digital Image Processing

1. 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

Explanation: Any array operation is carried out on a pixel by pixel basis.

2. The property indicating that the output of a linear operation due to the sum of two inputs is same as performing the operation on the inputs individually and then summing the results is called ___________
b) heterogeneity
c) homogeneity
d) None of the Mentioned

Explanation: This property is called additivity .

3. The property indicating that the output of a linear operation to a constant times as input is the same as the output of operation due to original input multiplied by that constant is called _________
b) heterogeneity
c) homogeneity
d) None of the Mentioned

Explanation: This property is called homogeneity .

4. Enhancement of differences between images is based on the principle of ____________
b) Homogeneity
c) Subtraction
d) None of the Mentioned

Explanation: A frequent application of image subtraction is in the enhancement of differences between images .

5. A commercial use of Image Subtraction is ___________
b) MRI scan
c) CT scan
d) None of the Mentioned

Explanation: Mask mode radiography is an important medical imaging area based on Image Subtraction.

6. Region of Interest (ROI) operations is commonly called as ___________
c) Dilation
d) None of the Mentioned

Explanation: A common use of image multiplication is Masking, also called ROI operation.

7. If every element of a set A is also an element of a set B, then A is said to be a _________ of set B.
a) Disjoint set
b) Union
c) Subset
d) Complement set

Explanation: A is called the subset of B.

8. Consider two regions A and B composed of foreground pixels. The ________ of these two sets is the set of elements belonging to set A or set B or both.
a) OR
b) AND
c) NOT
d) XOR

Explanation: This is called an OR operation.

9. Imaging systems having physical artefacts embedded in the imaging sensors produce a set of points called __________
a) Tie Points
b) Control Points
c) Reseau Marks
d) None of the Mentioned

Explanation: These points are called “known” points or “Reseau marks”.

10. Image processing approaches operating directly on pixels of input image work directly in ____________
a) Transform domain
b) Spatial domain
c) Inverse transformation
d) None of the Mentioned

Explanation: Operations directly on pixels of input image work directly in Spatial Domain.

Basic of Digital Image Processing

ALL unite digital Image Processing MCQ

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