Virtual Labs

Neighbourhood Operations

1. What is the main difference between a point operation and a neighbourhood operation?

a: A neighbourhood operation uses information from surrounding pixels Explanation

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b: A neighbourhood operation can be applied only to colour images Explanation

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c: A point operation always changes the image dimensions Explanation

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d: A point operation requires a filter matrix Explanation

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2. Which of the following is a linear neighbourhood operation discussed in the experiment?

a: Median filtering Explanation

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b: Gaussian filtering Explanation

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c: Image file conversion Explanation

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d: Pixel threshold selection Explanation

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3. Which filter is described as a nonlinear neighbourhood operation in the experiment?

a: Straight averaging filter Explanation

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b: Triangular filter Explanation

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c: Gaussian filter Explanation

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d: Median filter Explanation

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4. For a

3 \times 3

averaging filter, each coefficient is equal and the coefficients sum to

1

. What is the value of each coefficient?

\frac{1}{3}

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\frac{1}{6}

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\frac{1}{9}

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1

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5. An image contains isolated black and white pixels caused by salt-and-pepper noise. Which operation described in the experiment is particularly useful for removing this type of noise?

a: Median filtering Explanation

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b: Triangular filtering only Explanation

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c: Increasing the image dimensions Explanation

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d: Changing the file format Explanation

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6. In a linear neighbourhood operation, what is the role of the centre coefficient

w(0,0)

a: It specifies the image width Explanation

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b: It is the coefficient applied at the position of the current pixel Explanation

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c: It specifies the number of image channels Explanation

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d: It determines the border size automatically Explanation

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7. A

3 \times 3

neighbourhood window is applied to a pixel at the border of an image. What problem occurs if no border-handling method is used?

a: Some pixels required by the window are outside the image Explanation

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b: All filter coefficients become negative Explanation

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c: The centre pixel is removed from the image Explanation

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d: The filter automatically becomes nonlinear Explanation

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8. Suppose a neighbourhood filter has positive coefficients whose sum is

1

. Which effect is most consistent with the low pass filters described in the experiment?

a: Local smoothing of the image Explanation

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b: Guaranteed conversion to a binary image Explanation

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c: Removal of all image information Explanation

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d: Dependence only on the centre pixel Explanation

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9. Which statement best distinguishes the Gaussian filter from the median filter as presented in the experiment?

a: The Gaussian filter is nonlinear, while the median filter is linear Explanation

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b: Both filters use exactly the same type of operation Explanation

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c: The Gaussian filter uses weighted linear filtering, while the median filter uses a nonlinear ranking operation Explanation

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d: The Gaussian filter uses only the centre pixel, while the median filter uses the whole image Explanation

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