A. By introducing additional frequency components to the sampled function
B. By removing some frequency components from the sampled function
C. All of Mentioned
D. None of the mentioned
Answer: A
Aliasing corrupts the sampled image by introducing additional frequency components into the sampled function. These added components are called aliased frequencies.
12. How can one reduce the aliasing effect on an image?
A. By reducing the high-frequency components of the image by blurring the image
B. By increasing the high-frequency components of the image by blurring the image
C. By reducing the high-frequency components of the image by clarifying the image
D. By increasing the high-frequency components of the image by clarifying the image
Answer: A
Aliasing corrupts the sampled image by introducing additional frequency components to the sampled function. So, the principal approach for reducing the aliasing effects on an image is to reduce its high-frequency components by blurring the image before sampling.
13. 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.
14. 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 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.
15. 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.
16. 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.
17. 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.
18. 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’).
19. 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.
20. 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.
