1. Which of the following is a sharpening filter used in digital image processing?
(A) Gaussian Filter
(B) Median Filter
(C) Laplacian Filter
(D) Mean Filter
2. What is the main purpose of a sharpening filter?
(A) Reduce brightness
(B) Blur the image
(C) Enhance edges
(D) Remove noise
3. Which of the following operators is based on second-order derivatives?
(A) Sobel
(B) Prewitt
(C) Laplacian
(D) Roberts
4. Which sharpening method uses first-order derivatives?
(A) Laplacian
(B) Gaussian
(C) Gradient
(D) Average
5. Which directional operators are used for edge detection in the gradient method?
(A) Low-pass filters
(B) Sobel and Prewitt
(C) Median filters
(D) Mean and Gaussian
6. Which of the following best describes the Laplacian filter?
(A) Non-linear
(B) Directional
(C) Isotropic
(D) Adaptive
7. The Laplacian operator is used to:
(A) Blur the image
(B) Detect noise
(C) Detect edges without direction
(D) Color the image
8. Which filter emphasizes regions of rapid intensity change?
(A) Laplacian
(B) Gaussian
(C) Mean
(D) Uniform
9. What is a key disadvantage of the Laplacian filter?
(A) Too slow
(B) Increases noise
(C) Over-smooths image
(D) Reduces contrast
10. Which gradient operator computes the magnitude of the gradient?
(A) Sobel
(B) Laplacian
(C) Median
(D) Gaussian
11. Which of the following filters is most likely to enhance fine details?
(A) Laplacian
(B) Mean
(C) Gaussian
(D) Low-pass
12. Which of the following operators is used for edge detection in both x and y directions?
(A) Gaussian
(B) Laplacian
(C) Sobel
(D) Median
13. The Laplacian operator is sensitive to:
(A) Uniform intensity
(B) Random noise
(C) Low frequencies
(D) Large edges
14. In which situation is the use of gradient filters more advantageous?
(A) When detecting edges in noisy images
(B) When averaging color values
(C) When blurring the image
(D) When creating histograms
15. What is the effect of applying a Laplacian filter to a smooth image?
(A) No change
(B) High contrast
(C) Emphasis on uniform regions
(D) Enhancement of slight intensity variations
16. Which filter is generally applied after Laplacian to improve visual quality?
(A) Low-pass filter
(B) Mean filter
(C) Gaussian filter
(D) Original image is added
17. Sobel and Prewitt operators are examples of:
(A) Second-order derivatives
(B) High-pass filters
(C) First-order derivatives
(D) Smoothing filters
18. Which sharpening filter is directionally biased?
(A) Laplacian
(B) Gaussian
(C) Gradient
(D) Mean
19. Which of the following enhances edges equally in all directions?
(A) Sobel
(B) Laplacian
(C) Prewitt
(D) Roberts
20. Laplacian filter is defined using which mathematical concept?
(A) Integral
(B) Convolution
(C) Second-order derivative
(D) Histogram
21. What does a high gradient magnitude represent in an image?
(A) Smooth region
(B) Uniform color
(C) Rapid intensity change
(D) Noise
22. Which gradient operator uses a 3×3 kernel and includes smoothing?
(A) Sobel
(B) Laplacian
(C) Median
(D) Roberts
23. The Prewitt operator detects edges by approximating:
(A) Second derivative
(B) Average of neighboring pixels
(C) First derivative
(D) Noise variance
24. Which of the following sharpening methods is most sensitive to noise?
(A) Gradient
(B) Mean filter
(C) Laplacian
(D) Gaussian
25. Gradient filters help to detect edges by finding:
(A) Zero-crossings
(B) Intensity averages
(C) Local maxima and minima
(D) Intensity differences
26. What type of edges are Laplacian filters especially good at detecting?
(A) Only vertical edges
(B) Only horizontal edges
(C) Fine and sharp edges
(D) Blurred edges
27. Which edge detection filter does not involve directionality?
(A) Sobel
(B) Prewitt
(C) Laplacian
(D) Roberts
28. Which operator calculates the difference between adjacent pixel values?
(A) Sobel
(B) Laplacian
(C) Gradient
(D) Median
29. What is the main limitation of the Prewitt operator?
(A) Too slow
(B) Doesn’t detect color edges
(C) Less accurate in detecting diagonal edges
(D) Not applicable to grayscale images
30. Which edge detector is known for simplicity but poor noise performance?
(A) Sobel
(B) Roberts
(C) Prewitt
(D) Laplacian
31. Which filter computes the second derivative using the difference of neighboring pixels?
(A) Gradient
(B) Median
(C) Laplacian
(D) Gaussian
32. Which filter shows zero-crossings at edges?
(A) Laplacian
(B) Sobel
(C) Prewitt
(D) Median
33. The Sobel operator emphasizes which types of edges?
(A) Soft edges
(B) Strong vertical and horizontal edges
(C) Diagonal edges only
(D) Noisy edges
34. Which operator uses two masks to calculate edge magnitude and direction?
(A) Median
(B) Laplacian
(C) Sobel
(D) Gaussian
35. What happens when the Laplacian mask is applied twice?
(A) Blurring
(B) Noise removal
(C) Over-enhancement of edges
(D) No change
36. The Laplacian filter is usually combined with:
(A) Histogram equalization
(B) The original image
(C) Median filter
(D) Color enhancement
37. Which filter provides edge detection in real-time systems due to simplicity?
(A) Gaussian
(B) Sobel
(C) Roberts
(D) Prewitt
38. Which filter combines edge detection with slight smoothing?
(A) Sobel
(B) Laplacian
(C) Roberts
(D) Histogram
39. Which sharpening filter is most effective for binary edge maps?
(A) Laplacian
(B) Median
(C) Prewitt
(D) Roberts
40. A positive Laplacian kernel highlights:
(A) Valleys
(B) Bright regions
(C) Flat areas
(D) Dark regions
41. Which sharpening technique includes both horizontal and vertical edge components?
(A) Laplacian
(B) Sobel
(C) Mean filter
(D) Gaussian
42. In gradient-based edge detection, the edge direction is found using:
(A) Sine wave
(B) Histogram
(C) Arctangent of gradients
(D) Intensity difference
43. Which filter has a kernel with both positive and negative values?
(A) Laplacian
(B) Median
(C) Gaussian
(D) Mean
44. The Laplacian filter detects edges based on:
(A) Zero-crossings of second derivative
(B) Peak intensities
(C) Uniformity
(D) Histogram spread
45. Which of the following filters sharpens the image by subtracting a smoothed version?
(A) Unsharp masking
(B) Laplacian
(C) Gradient
(D) Median
46. In digital images, sharpening is often used to:
(A) Increase noise
(B) Reduce contrast
(C) Enhance image detail
(D) Remove color
47. Which gradient method is least effective at detecting weak edges?
(A) Sobel
(B) Roberts
(C) Prewitt
(D) Laplacian
48. Which sharpening method is most sensitive to pixel intensity differences?
(A) Gradient
(B) Laplacian
(C) Gaussian
(D) Mean
49. Which sharpening filter is direction-independent?
(A) Sobel
(B) Prewitt
(C) Laplacian
(D) Roberts
50. Which is not a common issue when using sharpening filters?
(A) Edge enhancement
(B) Noise amplification
(C) Contrast loss
(D) Color saturation
51. Which sharpening operator is based on local intensity differences?
(A) Gradient
(B) Gaussian
(C) Mean
(D) Histogram
