Virtual Labs

Point Operations

1. What is the main characteristic of a point operation in image processing?

a: The output pixel value depends only on the corresponding input pixel value Explanation

Explanation

b: The output pixel value depends only on neighbouring pixels Explanation

Explanation

c: The image must first be converted into a binary image Explanation

Explanation

d: The operation can be applied only to colour images Explanation

Explanation

2. For an 8-bit grayscale image, what is the usual valid range of a pixel value

p

1 \leq p \leq 256

Explanation

0 \leq p \leq 255

Explanation

0 \leq p \leq 256

Explanation

-255 \leq p \leq 255

Explanation

3. In the linear point transformation

q = sp + o

, which parameter determines the slope of the transformation?

o

Explanation

q

Explanation

s

Explanation

p

Explanation

4. A linear point transformation is given by

q = 4p + 160

. For an input pixel with

p = 20

, what is the transformed value before any range adjustment?

80

Explanation

180

Explanation

220

Explanation

240

Explanation

5. Which transformation is particularly useful for expanding a narrow range of low-intensity values while compressing higher-intensity values?

a: Logarithmic transformation Explanation

Explanation

b: Window function Explanation

Explanation

c: Clipping transformation Explanation

Explanation

d: Constant-value transformation Explanation

Explanation

6. In the clipping transformation, what happens to an input pixel value

p

that is greater than the upper limit

b

a: It is mapped to

0

Explanation

b: It is mapped to

255

for the 8-bit grayscale case Explanation

Explanation

c: It is multiplied by

s

Explanation

d: It is left unchanged in every case Explanation

Explanation

7. Consider a window function that preserves the input range

a \leq p \leq b

and maps values outside this range to

0

. What is the main purpose of this operation?

a: To preserve all gray levels without modification Explanation

Explanation

b: To make every pixel equal to

255

Explanation

c: To select a desired range of gray levels for the output Explanation

Explanation

d: To make the output depend on neighbouring pixels Explanation

Explanation

8. Two point transformations are applied to the same input image. Transformation A is linear, while Transformation B is logarithmic. Which statement best describes their difference?

a: Both transformations must produce identical output values Explanation

Explanation

b: Transformation A uses neighbouring pixels, while Transformation B uses one pixel Explanation

Explanation

c: Transformation A can only decrease pixel values, while Transformation B can only increase them Explanation

Explanation

d: The relationship between input and output pixel values is linear for A and nonlinear for B Explanation

Explanation

9. Suppose a point operation produces an output value

q

outside the valid range

0 \leq q \leq 255

. What is required before the value can be represented as a valid 8-bit grayscale pixel?

a: The value must be adjusted or mapped so that it lies within the valid grayscale range Explanation

Explanation

b: The value must always be replaced by the input pixel value Explanation

Explanation

c: The value must always be converted into a negative number Explanation

Explanation

d: The value must be made dependent on neighbouring pixels Explanation

Explanation