Virtual Labs

Affine Transformation

1. Which transformation should be used when the position of an image needs to be changed without changing its size or orientation?

a: Translation Explanation

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b: Rotation Explanation

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c: Scaling Explanation

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d: Bicubic interpolation Explanation

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2. If

s_x=s_y

during scaling, what happens to the proportions of the image?

a: They are always distorted. Explanation

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b: They are preserved. Explanation

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c: The image is rotated. Explanation

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d: The image is translated. Explanation

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3. Which statement about an affine transformation is correct?

a: It can only perform rotation. Explanation

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b: It can only change pixel intensity values. Explanation

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c: It can represent transformations such as translation, rotation, and scaling. Explanation

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d: It is an interpolation method. Explanation

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4. A transformed output location is calculated as

(3.89,17.26)

. Why is an interpolation method needed to obtain its pixel value from the original image?

a: The location is outside the image by definition. Explanation

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b: The transformation has removed the pixel. Explanation

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c: The image must always be converted to a binary image. Explanation

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d: The location does not correspond exactly to an integer pixel location on the original grid. Explanation

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5. Which interpolation method generally provides smoother results than nearest-neighbor interpolation by using the four surrounding pixels?

a: Bilinear interpolation Explanation

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b: Nearest-neighbor interpolation Explanation

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c: Inverse mapping Explanation

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d: Translation Explanation

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6. In inverse mapping, what is calculated for a pixel location in the transformed image?

a: Only the size of the original image. Explanation

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b: The corresponding location in the original image. Explanation

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c: Only the rotation angle. Explanation

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d: The number of interpolation methods available. Explanation

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7. A point

(4,0)

is rotated by

30^\circ

about the origin. Which transformed point is obtained approximately?

(3.46,2)

Explanation

(2,3.46)

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(-3.46,2)

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(4,2)

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8. An image is first translated and then rotated. If the order is changed so that the image is first rotated and then translated, what can happen?

a: The image must remain exactly the same. Explanation

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b: Both transformations are cancelled. Explanation

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c: The final transformed image may be different. Explanation

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d: Only the pixel intensity range changes. Explanation

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9. Which statement best compares nearest-neighbor, bilinear, and bicubic interpolation?

a: All three methods use exactly one neighbouring pixel. Explanation

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b: Nearest-neighbor uses the closest pixel, bilinear uses four surrounding pixels, and bicubic commonly uses a

4\times4

neighbourhood. Explanation

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c: Bilinear and bicubic interpolation do not require neighbouring pixels. Explanation

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d: Bicubic interpolation is always computationally simpler than nearest-neighbor interpolation. Explanation

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