Digital Image Processing Mcqs

Q:

Which of the following fact is true for the masks that includes diagonal neighbors than the masks that doesn’t?

A) Mask that excludes diagonal neighbors has more sharpness than the masks that doesn’t B) Mask that includes diagonal neighbors has more sharpness than the masks that doesn’t
C) Both masks have same sharpness result D) None of the mentioned
 
Answer & Explanation Answer: B) Mask that includes diagonal neighbors has more sharpness than the masks that doesn’t

Explanation: Including diagonal neighbor pixels enhances sharpness of the image. So, Mask that includes diagonal neighbors has more sharpness than the masks that doesn’t.

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Q:

Why is scaling of Laplacian filtered images necessary?

A) Because it contain high positive values B) Because it contain high negative value
C) Because it contain both positive and negative values D) None of the mentioned
 
Answer & Explanation Answer: C) Because it contain both positive and negative values

Explanation: A Laplacian filtered image contain both positive and negative values of comparable magnitudes. So, scaling is necessary.

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10
Q:

An enhanced image can be obtained as: g(x,y)=f(x,y)-∇2 f(x,y), where Laplacian is being subtracted from f(x, y) the input image. What does this conclude?

A) That the center spike would be negative B) That the immediate neighbors of center spike would be positive.
C) All of the mentioned D) None of the mentioned
 
Answer & Explanation Answer: C) All of the mentioned

Explanation: For the above given enhanced image the Laplacian subtraction suggest that the center coefficient of Laplacian mask is negative and so the center spike is negative with its immediate neighbors being positive.

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7
Q:

Computing the Fourier transform of the Laplacian result in spatial domain is equivalent to multiplying the F(u, v), Fourier transformed function of f(x, y) an input image, and H(u, v), the filter used for implementing Laplacian in frequency domain. This dual relationship is expressed as _________

A) Fourier transform pair notation B) Laplacian
C) Gradient D) None of the mentioned
 
Answer & Explanation Answer: A) Fourier transform pair notation

Explanation: The Fourier transform of the Laplacian result in spatial domain is equivalent to multiplying the F(u, v) and H(u, v). This dual relationship is expressed as Fourier transform pair notation given by: ∇² f(x,y)-[(u – M/2)²+ (v – N/2)²]F(u,v), for an image of size M *N.

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10
Q:

Assuming that the origin of F(u, v), Fourier transformed function of f(x, y) an input image, has been correlated by performing the operation f(x, y)(-1)x+y prior to taking the transform of the image. If F and f are of same size M*N, then which of the following is an expression for H(u, v), the filter used for implementing Laplacian in frequency domain?

A) H(u, v)= -(u²+ v²) B) H(u, v)= -(u²– v²)
C) H(u, v)= -[(u – M/2)²+ (v – N/2)²]. D) H(u, v)= -[(u – M/2)²– (v – N/2)²].
 
Answer & Explanation Answer: C) H(u, v)= -[(u – M/2)²+ (v – N/2)²].

Explanation: The given operation f(x, y)(-1)x+y shifts the center transform so that (u, v)=(0, 0) is at point (M/2, N/2) and hence the filter is: H(u, v)= -[(u – M/2)²+ (v – N/2)²].

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11
Q:

Assuming that the origin of F(u, v), Fourier transformed function of f(x, y) an input image, has been correlated by performing the operation f(x, y)(-1)x+y prior to taking the transform of the image. If F and f are of same size M*N, where does the point (u, v) =(0,0) shifts?

A) (M -1, N -1) B) (M/2, N/2)
C) (M+1, N+1) D) (0, 0)
 
Answer & Explanation Answer: B) (M/2, N/2)

Explanation: The given operation f(x, y)(-1)x+y shifts the center transform so that (u, v)=(0, 0) is at point (M/2, N/2) for F and f of same size M*N.

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10
Q:

Assuming that the origin of F(u, v), Fourier transformed function of f(x, y) an input image, has been correlated by performing the operation f(x, y)(-1)x+y prior to taking the transform of the image. If F and f are of same size, then what does the given operation is/are supposed to do?

A) Resize the transform B) Rotate the transform
C) Shifts the center transform D) All of the mentioned
 
Answer & Explanation Answer: C) Shifts the center transform

Explanation: The given operation f(x, y)(-1)x+y shifts the center transform so that (u, v)=(0,0) is at point (M/2, N/2) for F and f of same size M*N.

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9
Q:

The Laplacian in frequency domain is simply implemented by using filter __________

A) H(u, v)= -(u²– v²) B) H(u, v)= -(1)
C) H(u, v)= -(u²+ v²) D) none of the mentioned
 
Answer & Explanation Answer: C) H(u, v)= -(u²+ v²)

Explanation: Laplacian in frequency domain is: I[(∂² f(x,y))/∂x² +(∂² f(x,y))/∂y² ]= -(u²+v²)F(u,v), where ℑ is the Fourier transform operator and F(u, v) is Fourier transformed function of f(x, y) and -(u²+ v²) is the filter.

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