Digital Image Processing Nptel Week 3 Answers
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Digital Image Processing Nptel Week 3 Answers (July-Dec 2025)
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Question 1. What is discretizing pixel intensities of an image?
a) Sampling
b) Quantization
c) Framing
d) Both A and B
Question 2. Which of the following transformation matrix corresponds to rotation about x-axis?
a)
1 0 0 0
0 cosθ –sinθ 0
0 sinθ cosθ 0
0 0 0 1
b)
1 0 0 0
0 –sinθ cosθ 0
0 0 0 1
c)
cosθ sinθ 0 0
–sinθ cosθ 0 0
0 0 1 0
d)
a 0 0 1
0 0 0 2
Question 3. How many cameras are required to find 3-D point using image coordinates of camera?
a) At least 1
b) At least 2
c) At least 3
d) At least 4
Question 4. For a stereo pair, one camera is shifted along x-axis with respect to other. Imaging plane is XY plane. If B is the baseline between the cameras, f is the focal length, and (xₗ – xᵣ) is the disparity along x-axis then which of the following is true?
a) Z = (f × B) / (xₗ – xᵣ)
b) Z = B + f
c) Z = f – B
d) Z = (xₗ – xᵣ) / (f × B)
Question 5. Two identical cameras having focal length of 0.04 m are used for stereo imaging. If the camera displacement along X-axis is 6.0 cm, left image point corresponding to a world point W is (0.2 mm, 0.4 mm) and the corresponding right image point is (0.4 mm, 0.4 mm), find out the 3-D location of W with respect to a world coordinate system aligned with the coordinate system of the left camera.
a) (–60 cm, –90 cm, 1240 cm)
b) (6 cm, 12 cm, –1196 cm)
c) (6 cm, 9 cm, 1204 cm)
d) (–6 cm, –9 cm, 120.4 cm)
Question 6. Which of the following deals with the conversion of three-dimensional world coordinate to two-dimensional image?
a) Perspective Transformation
b) Rotation
c) Linear Transformation
d) Non-linear Mapping
Question 7. For stereo image pair, how does disparity of 3D point vary with object depth?
a) Disparity increases as object depth increases
b) Disparity is independent of object depth
c) Disparity decreases as object depth increases
d) None of these
Question 8. For a camera with focal length of 0.05, find out the locus of the points which will be imaged at location (0.5, 0.5) on the Image plane. Assume the camera coordinate system and world coordinate system to be perfectly aligned.
a) X = 0.1 – 4Z, Y = –0.2 + 6Z
b) X = 0.3 – 6Z, Y = –0.3 + 6Z
c) X = 0.5 – 10Z, Y = 0.5 + 10Z
d) X = 0.5 – 10Z, Y = 0.5 – 10Z
Question 9. The figure 2 is first translated by vector [1, –1] and then scaled up by a factor of 2. What is the transformed figure?
a)
(0,4), (4,4)
(0,0), (4,0)
b)
(0,1), (4,1)
(0,–3), (4,3)
c)
(4,0), (0,0)
(0,4), (4,0)
d) None of the above
Question 10. The figure 1 is first scaled up by a factor 2 and then translated by vector [1, –1]. What is the transformed figure?
a)
(0,1), (4,1)
(0,–3), (4,3)
b)
(4,1), (0,1)
(0,–1), (4,3)
c)
(4,–1), (0,–1)
(0,–1), (4,–1)
d) None of the above
These are Digital Image Processing Nptel Week 3 Answers