1. In terms of Sampling and Quantization, Zooming and Shrinking may be viewed as ___________
A. Oversampling for both
B. Oversampling and Undersampling respectively
C. Undersampling and Oversampling respectively
D. Undersampling for both
Answer: B
Oversampling increases the number of samples in the image, i.e. Zooming. Undersampling decreases the number of samples in the image, i.e. Shrinking.
2. The two steps: one is the creation of new pixel locations, and the other is the assignment of gray levels to those new locations are involved in ____________
A. Shrinking
B. Zooming
C. All of the mentioned
D. None of the mentioned
Answer: B
Suppose that we have an image of size500*500pixels and we want to enlarge it 1.5 times to 750*750 pixels.
Creation of new Pixels: One of the easiest ways to visualize zooming is laying an imaginary 750*750 grid over the original image and so there would be less spacing by one pixel in the grid because we are fitting it over a smaller image.
Assignment of gray levels to new locations: To perform a gray-level assignment for any point in the overlay, we assign its gray level to the new pixel in the grid its closest pixel in the original image.
When the above steps are done with all points in the overlay grid, we expand it to the originally specified size to obtain the zoomed image.
3. While Zooming, In order to perform a gray-level assignment for any point in the overlay, we assign its gray level to the new pixel in the grid its closest pixel in the original image. What’s this method of gray-level assignment called?
A. Neighbor Duplication
B. Duplication
C. Nearest neighbor Interpolation
D. None of the mentioned
Answer: C
Because we look for the closest pixel in the original image and assign its gray level to the new pixel in the grid.
4. A special case of nearest-neighbor Interpolation that just duplicates the pixels the number of times to achieve the desired size, is known as ___________
A. Bilinear Interpolation
B. Contouring
C. Ridging
D. Pixel Replication
Answer: D
A special case of nearest-neighbor interpolation is Pixel replication and is applicable when we want to increase the size of an image an integer number of times.
For example, doubling the size of an image is achieved by duplicating each column, and hence image size gets doubled in the horizontal direction. Then, we duplicate each row of the enlarged image to double the size in the vertical direction. Similarly, enlarging the image by an integer number of times (triple, quadruple, and so on) is possible.
5. Nearest neighbor Interpolation has an undesirable feature, that is _________
A. Aliasing effect
B. False contouring effect
C. Ridging effect
D. Checkerboard effect
Answer: D
At greater magnification nearest neighbor Interpolation has the undesirable feature that it produces a checkerboard effect.
6. What does the bilinear Interpolation do for a gray-level assignment?
A. Assign gray level to the new pixel using its right neighbor
B. Assign a gray level to the new pixel using its left neighbor
C. Assign gray level to the new pixel using its four nearest neighbors
D. Assign a gray level to the new pixel using its eight nearest neighbors
Answer: C
Bilinear interpolation uses the four nearest neighbors of the new pixel. Let (x’, y’) be the coordinates of a point in the zoomed image, and the gray level assigned to the point is v(x, y’).
For bilinear interpolation, the assigned gray level is given by
v(x’, y’) = ax’ + by’ + cx’y’ + d
Here, a, b, c, and d are determined from the four equations in four unknowns that can be written using the four nearest neighbors of point (x’, y’).
7. Row-column deletion method of Image Shrinking is an equivalent process to which method of Zooming?
A. Bilinear Interpolation
B. Contouring
C. Pixel Replication
D. There is no such equivalent process
Answer: C
Row-column deletion method is used to shrink an image by one-half, one-fourth, and so on.
In the case of one-half, we delete every other row and column.
8. Image Shrinking has an undesirable feature, that is ____________
A. Aliasing effect
B. False contouring effect
C. Ridging effect
D. Checkerboard effect
Answer: A
Although Image Shrinking uses the grid analogy of nearest-neighbor interpolation, but that we now expand the grid to fit over the original image, do gray-level nearest neighbor or bilinear interpolation, causing the possible aliasing effect, and then shrink the grid back to its original specified size.
9. State for the validation of the statement:
“In general-purpose for a digital image of zooming and shrinking, where Bilinear Interpolation generally is the method of choice over nearest-neighbor Interpolation”.
A. True
B. False
Answer: A
For cases 32*32 to 1024*1024, the data is rather lost in nearest neighbor Interpolation, but the result of Bilinear Interpolation remains reasonably good for the same.
10. A pixel p at coordinates (x, y) has neighbors whose coordinates are given by:
(x+1, y), (x-1, y), (x, y+1), (x, y-1)
This set of pixels is called ____________
A. 4-neighbors of p
B. Diagonal neighbors
C. 8-neighbors
D. None of the mentioned
Answer: A
The given set of a neighbor pixel is 1 unit distance to the right, left, up, and below respectively from pixel p(x, y). So, are called 4-neighbors of p.
11. A pixel p at coordinates (x, y) has neighbors whose coordinates are given by:
(x+1, y+1), (x+1, y-1), (x-1, y+1), (x-1, y-1)
This set of pixels is called ____________
A. 4-neighbors of p
B. Diagonal neighbors
C. 8-neighbors
D. None of the mentioned
Answer: B
The given set of a neighbor pixel is 1 unit distance to the right-up diagonal, right-down diagonal, left-up diagonal, and left-down diagonal respectively from pixel p(x, y). So, are called Diagonal neighbors of p.
12. What is the set of pixels of 8-neighbors of pixel p at coordinates (x, y)?
The set of pixels of 4-neighbors of p and Diagonal neighbors of p together are called 8-neighbors of pixel p(x, y).
14. Two pixels p and q having gray values from V, the set of gray-level values used to define adjacency, are m-adjacent if:
A. q is in N4(p)
B. q is in ND(p) and the set N4(p) ∩ N4(q) has no pixels whose values are from V
C. Any of the mentioned
D. None of the mentioned
Answer: C
Mixed adjacency is a modified form of 8-adjacency.
The above conditioned Two pixels p and q are m-adjacent if:
q is in N4(p), or q is in ND(p) and the set N4(p) ∩ N4(q) has no pixels whose values are from V.
15. Let S, a subset of pixels in an image, is said to be a connected set if:
A. If for any pixel p in S, the set of pixels that are connected to it in Sis only one
B. If it only has one connected component
C. If S is a region
D. All of the mentioned
Answer: D
For a subset of pixels in an image S.
For any pixel p in S, the set of pixels is called a connected component of S if connected to p in S. The set S is called a connected set if it only has one connected component. S is a region of the image if S is a connected set.
16. Let R be a subset of pixels in an image. How can we define the contour of R?
A. If R is a region, and the set of pixels in R has one or more neighbors that are not in R
B. If R is an entire image, then the set of pixels in the first and last rows and columns of R
C. All of the mentioned
D. None of the mentioned
Answer: C
For a subset of pixels in an image R.
The boundary or contour of a region R is the set of pixels in the region that have one or more neighbors that are not in R.
In case R is an entire image, then its boundary is defined as the set of pixels in the first and last rows and columns of the image.
17. For pixels p(x, y), q(s, t), and z(v, w), D is a distance function or metric if:
A. D(p, q) ≥ 0
B. D(p, q) = D(q, p)
C. D(p, z) ≤ D(p, q) + D(q, z)
D. All of the mentioned
Answer: D
For pixels p(x, y), q(s, t), and z(v, w), D is a distance function or metric if:
(i) D(p, q) ≥ 0, (D(p, q) = 0 if p=q),
(ii) D(p, q) = D(q, p), and
(iii) D(p, z) ≤ D(p, q) + D(q, z).
18. For pixels p(x, y), q(s, t), the Euclidean distance between p and q is defined as:
A. D(p, q) = [(x – s)2 + (y – t)2]1/2
B. D(p, q) = |x – s| + |y – t|
C. D(p, q) = max (|x – s| + |y – t|)
D. None of the mentioned
Answer: A
The Euclidean distance for pixels p(x, y), q(s, t) is:
D(p, q) = [(x – s)2 + (y – t)2]1/2.
19. For pixels p(x, y), q(s, t), the city-block distance between p and q is defined as:
A. D(p, q) = [(x – s)2 + (y – t)2]1/2
B. D(p, q) = |x – s| + |y – t|
C. D(p, q) = max (|x – s| + |y – t|)
D. None of the mentioned
Answer: B
The city-block distance for pixels p(x, y), q(s, t) is the D4 distance given by:
D(p, q) = |x – s| + |y – t|.
20. For pixels p(x, y), q(s, t), the chessboard distance between p and q is defined as:
A. D(p, q) = [(x – s)2 + (y – t)2]1/2
B. D(p, q) = |x – s| + |y – t|
C. D(p, q) = max (|x – s| + |y – t|)
D. None of the mentioned
Answer: C
The chessboard distance for pixels p(x, y), q(s, t) is the D8 distance given by:
D(p, q) = max (|x – s| + |y – t|).
