Image Enhancement - Image Processing and Analysis - Geomatics Engineering Previous Year Questions

1

2024 · Geomatics Engineering · Image Processing and Analysis · Image Enhancement

Geomatics Engineering (GE) 2024

The histogram equalization applied to a digital image generally DOES NOT yield a truly uniform histogram of the transformed image due to

A

discrete nature of pixel values

B

poor contrast of the original image

C

low frequency image information

D

presence of edges

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2

2024 · Geomatics Engineering · Image Processing and Analysis · Image Enhancement

Geomatics Engineering (GE) 2024

Which type of contrast stretching is represented by the following figure?

A

Linear contrast stretch

B

Multiple linear stretch

C

Logarithmic stretch

D

Gaussian stretch

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3

2024 · Geomatics Engineering · Image Processing and Analysis · Image Enhancement

Geomatics Engineering (GE) 2024

Contrast enhancement is a type of _____ enhancement.

A

spectral

B

spatial

C

radiometric

D

temporal

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4

2024 · Geomatics Engineering · Image Processing and Analysis · Image Enhancement

Geomatics Engineering (GE) 2024

Which of the following filters can be used to suppress the low frequency component of a raster image?

A

(i)

B

(ii)

C

(iii)

D

(iv)

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5

2024 · Geomatics Engineering · Image Processing and Analysis · Image Enhancement

Geomatics Engineering (GE) 2024

In an image with 6-bit quantization level, the pixel values of a scene are between 25 and 55. A linear contrast stretch is applied to the image covering the full dynamic range. A pixel value 40 in the original image will be mapped to ______ (rounded off to nearest integer) in the stretched image.

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6

2025 · Geomatics Engineering · Image Processing and Analysis · Image Enhancement

Geomatics Engineering (GE) 2025

Piecewise linear contrast stretch is performed on an 8-bit image. The output \(BV_{out}\) would be zero for input value \(BV_{in} \leq 80\). The output \(BV_{out}\) would be 255 for \(BV_{in} > 120\). For the remaining input values, \(BV_{out} = (2 \times BV_{in}) - 20\).
If \(BV_{in} = 120\), then \(BV_{out}\) is ______ (Answer in integer).

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7

2025 · Geomatics Engineering · Image Processing and Analysis · Image Enhancement

Geomatics Engineering (GE) 2025

A remote sensing image is acquired from an IRS series satellite. Initially a two-dimensional filter with transfer function \( H(u, v) = \exp \left( \frac{-D^2(u,v)}{2D_0^2} \right) \) is applied to reduce scan line effects. Here \( D(u,v) \) is the distance from center of the frequency rectangle, and \( D_0 \) is the cutoff frequency. Which one of the following will be the transfer function for the corresponding filter to detect the edges in the image?

A

1 - \exp \left( \frac{-D^2(u,v)}{2D_0^2} \right)

B

\(\exp \left( \frac{-D^2(u,v)}{2D_0^2} \right)\)

C

1 + \exp \left( \frac{-D^2(u,v)}{2D_0^2} \right)

D

1 - \exp \left( \frac{D^2(u,v)}{2D_0^2} \right)

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8

2025 · Geomatics Engineering · Image Processing and Analysis · Image Enhancement

Geomatics Engineering (GE) 2025

The histogram of a red band in a 3-bit satellite image is shown below. Which of the following statements is/are correct?

A

There are more darker pixels in the image

B

There are more brighter pixels in the image

C

The mean digital number of the image is 1250

D

It may be predicted that approximately 40% of area in the image is covered by material with low spectral albedo in red band

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9

2022 · Geomatics Engineering · Image Processing and Analysis · Image Enhancement

Geomatics Engineering (GE) 2022

Choose the CORRECT statement(s)

A

True Color Composite is produced by superimposing Red band in Red, Green band in Green, and Blue band in Blue color.

B

True Color Composite is produced by superimposing Blue band in Red, Green band in Green, and Red band in Blue color.

C

Standard False Color Composite is produced by superimposing Near Infrared band in Red, Red band in Green, and Green band in Blue color.

D

Standard False Color Composite is produced by superimposing Green band in Red, Green band in Green, and Near Infrared band in Blue color.

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10

2022 · Geomatics Engineering · Image Processing and Analysis · Image Enhancement

Geomatics Engineering (GE) 2022

When the histogram of an image is non-Gaussian in nature, the type of linear contrast enhancement preferred to be used is

A

Piece-wise Linear Contrast Stretching

B

Min-max Linear Contrast Stretching

C

Percentage Linear Contrast Stretching

D

Standard Deviation Contrast Stretching

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11

2022 · Geomatics Engineering · Image Processing and Analysis · Image Enhancement

Geomatics Engineering (GE) 2022

Match the CORRECT option(s) for the types of filters given in (I), (II), (III), and (IV) with their kernels given in (P), (Q), (R), and (S).

A

I - P and II - Q

B

III - R and IV - S

C

I - P and IV - Q

D

II - R and III - S

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12

2022 · Geomatics Engineering · Image Processing and Analysis · Image Enhancement

Geomatics Engineering (GE) 2022

The decorrelation stretch enhances colour differences and removes inter-band ______.

A

decorrelation

B

contradiction

C

correlation

D

relationship

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13

2022 · Geomatics Engineering · Image Processing and Analysis · Image Enhancement

Geomatics Engineering (GE) 2022

The minimum and maximum Digital Number (DN) values of an image are 30 and 55, respectively. If the input DN value of a pixel is 35, the output DN value after linear contrast stretch of an 8-bit data is ______ (in integer).

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14

2023 · Geomatics Engineering · Image Processing and Analysis · Image Enhancement

Geomatics Engineering (GE) 2023

The value at the center pixel of the image at (1) obtained after applying the filter given at (2) is ________

A

70

B

68

C

69

D

71

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15

2023 · Geomatics Engineering · Image Processing and Analysis · Image Enhancement

Geomatics Engineering (GE) 2023

Consider the histogram of an 8-bit image given below at (1). A piece-wise linear contrast stretch given at (2) is applied on the said image. The minimum and maximum pixel values of the image obtained after applying the given contrast stretch are __________ (minimum value) and __________ (maximum value), respectively.

A

17, 176

B

17, 120

C

20, 176

D

20, 120

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16

2026 · Geomatics Engineering · Image Processing and Analysis · Image Enhancement

Geomatics Engineering (GE) 2026

Which one of the following is NOT a linear raster operation?

A

Histogram equalization

B

Averaging filter

C

Convolution with a Gaussian kernel

D

Laplacian edge detection

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17

2026 · Geomatics Engineering · Image Processing and Analysis · Image Enhancement

Geomatics Engineering (GE) 2026

Let \(f(x, y)\) be an image with the histogram as shown in the figure. X-axis denotes grey levels (r) and Y-axis denotes the probability (p) of occurrence of the grey levels.
What is the variance of the equalized image?

A

2/27

B

3/27

C

2/3

D

1/27

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18

2026 · Geomatics Engineering · Image Processing and Analysis · Image Enhancement

Geomatics Engineering (GE) 2026

An 8-bit remote sensing image has brightness values ranging from 24 to 120. While applying the minimum-maximum contrast stretch, which of the following statements is/are CORRECT?

A

The original brightness values between 24 and 120 would be linearly distributed between 0 and 255

B

An original brightness value of 48 would become approximately 64

C

The original brightness values between 24 and 120 would be linearly distributed between 24 and 255

D

An original brightness value of 36 would become approximately 46

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19

2026 · Geomatics Engineering · Image Processing and Analysis · Image Enhancement

Geomatics Engineering (GE) 2026

Which of the following options is/are INCORRECT?

A

Negative images are formed by a non-linear transformation of digital images

B

A thresholding function is used to produce a two-level binary digital image

C

Logarithmic transformation of an image is used to expand the values of dark pixels in a digital image

D

Power law transformation with fractional exponent is used to map dark input values of an image into a wider range of output values

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