1. Which of the following filters is used to remove high-frequency components in an image?
(A) High-pass filter
(B) Laplacian filter
(C) Low-pass filter
(D) Gradient filter
2. Which filter enhances the edges and fine details in an image?
(A) Mean filter
(B) Low-pass filter
(C) Gaussian filter
(D) High-pass filter
3. What is the main purpose of a low-pass filter?
(A) Edge detection
(B) Noise amplification
(C) Image smoothing
(D) Detail enhancement
4. High-pass filters are primarily used for:
(A) Blurring
(B) Smoothing
(C) Sharpening
(D) Color enhancement
5. Which frequency components are retained by low-pass filters?
(A) High frequencies only
(B) Low frequencies only
(C) All frequencies
(D) Zero frequency only
6. A low-pass filter in the frequency domain suppresses:
(A) Low frequencies
(B) Mid frequencies
(C) High frequencies
(D) Zero frequency
7. What kind of features are preserved by high-pass filtering?
(A) Smooth regions
(B) Flat intensities
(C) Noise
(D) Edges and boundaries
8. Applying a high-pass filter to an image makes it appear:
(A) Smoother
(B) Blurred
(C) Sharper
(D) Dimmer
9. Which filter is more suitable for removing Gaussian noise?
(A) High-pass
(B) Low-pass
(C) Sobel
(D) Laplacian
10. Which of the following best describes a low-pass filter in spatial domain?
(A) Second derivative filter
(B) Edge detector
(C) Averaging filter
(D) Binary threshold filter
11. What is the effect of applying a low-pass filter on a noisy image?
(A) Amplifies the noise
(B) Makes noise more visible
(C) Reduces noise
(D) Detects edges
12. What happens when a high-pass filter is applied to a uniform image?
(A) Blurring occurs
(B) Noise is removed
(C) Edges are enhanced
(D) No significant change
13. Low-pass filters are not ideal for:
(A) Denoising
(B) Edge detection
(C) Smoothing
(D) Blur reduction
14. Which of the following filters can cause ringing artifacts?
(A) Ideal low-pass
(B) Gaussian low-pass
(C) Median filter
(D) Butterworth high-pass
15. What is the ideal outcome of high-pass filtering in image analysis?
(A) Smooth texture
(B) Enhanced contrast
(C) Extracted edges
(D) Reduced detail
16. The high-pass filtering operation in frequency domain involves:
(A) Multiplying by a low-pass mask
(B) Multiplying by a high-pass mask
(C) Subtracting the original from the blurred
(D) Applying a binary threshold
17. Which of the following would be a frequency domain representation of low-pass filtering?
(A) Passes high frequencies
(B) Attenuates low frequencies
(C) Attenuates high frequencies
(D) Amplifies all frequencies
18. Which function is used to create smooth low-pass filters?
(A) Laplacian function
(B) Butterworth function
(C) Delta function
(D) Impulse function
19. Which type of low-pass filter does not have a sharp cutoff?
(A) Ideal
(B) Gaussian
(C) Band-reject
(D) Notch filter
20. Why are high-pass filters sensitive to noise?
(A) They enhance low-frequency signals
(B) They ignore all variations
(C) They amplify sudden changes
(D) They use smoothing kernels
21. Which filter type is most likely to retain the original image structure while removing high-frequency noise?
(A) Median
(B) High-pass
(C) Ideal low-pass
(D) Gaussian low-pass
22. Which one is a drawback of ideal low-pass filtering?
(A) Slow processing
(B) Causes distortion in low frequencies
(C) Causes ringing artifacts
(D) Poor edge enhancement
23. What is the cutoff frequency in a low-pass filter?
(A) The highest frequency allowed to pass
(B) The lowest frequency blocked
(C) Frequency with maximum amplification
(D) The mean of high and low frequencies
24. What is the main difference between high-pass and low-pass filtering?
(A) One sharpens while the other smooths
(B) One uses color, the other grayscale
(C) One operates in time domain
(D) One increases resolution
25. Which of the following filters is suitable for edge detection in frequency domain?
(A) Gaussian low-pass
(B) Ideal low-pass
(C) Butterworth high-pass
(D) Mean filter
26. What is the shape of the transfer function in an ideal low-pass filter?
(A) Parabolic
(B) Rectangular
(C) Exponential
(D) Triangular
27. What kind of spatial domain filter corresponds to a low-pass filter in frequency domain?
(A) Sobel
(B) Prewitt
(C) Averaging
(D) Roberts
28. High-pass filters in the frequency domain are designed to:
(A) Remove edges
(B) Enhance flat regions
(C) Highlight high frequencies
(D) Suppress noise only
29. What is a common drawback of using high-pass filters on real images?
(A) Over-smoothing
(B) Over-sharpening and noise enhancement
(C) Brightness loss
(D) Color bleeding
30. Which filter can be used to smooth an image in frequency domain?
(A) Laplacian
(B) Ideal low-pass
(C) Sobel
(D) Roberts
31. What is a typical application of low-pass filtering in image processing?
(A) Edge enhancement
(B) Noise addition
(C) Blur creation
(D) Histogram equalization
32. Which high-pass filter has a smoother transition band?
(A) Ideal
(B) Gaussian
(C) Laplacian
(D) Median
33. What is the frequency domain equivalent of spatial domain blurring?
(A) High-pass filtering
(B) Sharpening
(C) Low-pass filtering
(D) Contrast enhancement
34. Which filter may cause aliasing if not used properly?
(A) Gaussian
(B) Ideal high-pass
(C) Ideal low-pass
(D) Median
35. What is the visual effect of applying a high-pass filter?
(A) Increased smoothness
(B) Edge enhancement
(C) Uniform color
(D) Increased noise
36. What is the primary concern while designing high-pass filters?
(A) Avoiding over-smoothing
(B) Preserving low-frequency content
(C) Amplifying background
(D) Reducing edge contrast
37. A perfect high-pass filter passes:
(A) Frequencies below the cutoff
(B) All frequencies
(C) Only frequencies above the cutoff
(D) No frequencies
38. A Gaussian low-pass filter is preferred over ideal due to:
(A) Simpler structure
(B) No ringing
(C) Higher sharpness
(D) Lower processing
39. What is the consequence of increasing cutoff frequency in a low-pass filter?
(A) More blurring
(B) More sharpening
(C) More detail preservation
(D) Edge loss
40. What is the response of a low-pass filter to a sudden intensity change?
(A) Enhancement
(B) Smoothing
(C) Amplification
(D) No effect
41. High-pass filters suppress which part of the image spectrum?
(A) High-frequency
(B) All-frequency
(C) Low-frequency
(D) No-frequency
42. In digital image processing, low-pass filters are implemented to reduce:
(A) Sharpness
(B) Brightness
(C) Noise
(D) Saturation
43. Which filter is not frequency-selective?
(A) Gaussian
(B) Median
(C) Ideal
(D) Butterworth
44. What type of transition is observed in a Butterworth filter?
(A) Abrupt
(B) Linear
(C) Gradual
(D) No transition
45. Which filter has a smooth frequency response and no sharp edges?
(A) Ideal
(B) Laplacian
(C) Gaussian
(D) Roberts
46. What is the unit of cutoff frequency in image filtering?
(A) Pixels
(B) Hertz
(C) Radians
(D) Cycles per unit distance
47. Which spatial operation is similar to high-pass filtering?
(A) Averaging
(B) Differentiation
(C) Integration
(D) Histogram equalization
48. Why is Gaussian filtering widely used in practice?
(A) Simple kernel
(B) Fast computation
(C) No ringing effect
(D) Easy to invert
49. A high-pass filter kernel often includes:
(A) Only positive weights
(B) All weights equal
(C) Both positive and negative weights
(D) No weights
50. Which one of the following is true about low-pass filters?
(A) They highlight noise
(B) They detect edges
(C) They blur images
(D) They use subtraction
