Adaptive Median Filter Quiz and Flashcards: Expression for Image Processing

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Questions and Answers

What is the primary advantage of adaptive median filtering over median filtering?

It can handle less spatially dense impulse noise

It can handle more spatially dense impulse noise and performs some smoothing (correct)

It is a simpler algorithm to implement

It removes all types of noise from the image

What are the three main purposes of the adaptive median filter?

Remove all types of noise, provide smoothing, and reduce distortion

Remove impulse noise, provide smoothing, and reduce distortion (correct)

Remove Gaussian noise, provide smoothing, and reduce distortion

Remove salt and pepper noise, remove Gaussian noise, and reduce distortion

What is the key insight in the adaptive median filter?

The filter size is always minimum

The filter size remains constant

The filter size changes depending on the characteristics of the image (correct)

The filter size is always maximum

What is the difference between the median filter and the average filter?

Median filter is used for impulse noise, while average filter is used for Gaussian noise Signup and view all the answers

What is the primary goal of the adaptive median filter in terms of noise reduction?

To remove only impulse noise from the image Signup and view all the answers

What is the purpose of the level B in the adaptive median filter algorithm?

To output the final filtered pixel value Signup and view all the answers

What type of noise is typically removed by a max filter?

Pepper noise Signup and view all the answers

What is the primary advantage of an adaptive filter over a fixed filter?

It adapts to local image characteristics Signup and view all the answers

What is the purpose of the alpha-trimmed mean filter?

To remove multiple types of noise from an image Signup and view all the answers

What is the main difference between a median filter and an average filter?

The median filter is more resistant to outliers Signup and view all the answers

What is the effect of applying a 3x3 max filter to an image corrupted by pepper noise?

The noise is reduced Signup and view all the answers

What is the primary application of a median filter?

Noise reduction Signup and view all the answers

What is the purpose of using spatial filters in image processing?

To remove different kinds of noise Signup and view all the answers

What is the main difference between the arithmetic mean filter and the geometric mean filter?

The arithmetic mean filter uses a sum, while the geometric mean filter uses a product Signup and view all the answers

Which type of filter is suitable for removing impulse noise in an image?

Median filter Signup and view all the answers

What is the advantage of using an adaptive median filter over a non-adaptive median filter?

It can adapt to the local noise characteristics Signup and view all the answers

What is the formula for the arithmetic mean filter?

fˆ(x, y) = 1/mn * ∑g(s, t)∈Sxy Signup and view all the answers

Which type of filter is more suitable for image smoothing, the median filter or the arithmetic mean filter?

The arithmetic mean filter is more suitable for image smoothing Signup and view all the answers

Study Notes

Adaptive Median Filtering

The adaptive median filter can handle spatially dense impulse noise and performs some smoothing for non-impulse noise.
The filter size changes depending on the characteristics of the image.
The algorithm has three purposes: remove impulse noise, provide smoothing of other noise, and reduce distortion.

Notation

zmin: minimum grey level in Sxy
zmax: maximum grey level in Sxy
zmed: median of grey levels in Sxy
zxy: grey level at coordinates (x, y)
Smax: maximum allowed size of Sxy

Level A

A1 = zmed - zmin
A2 = zmed - zmax
If A1 > 0 and A2 < 0, Go to level B
Else increase the window size
If window size ≤ Smax, repeat Level A
Else output zmed

Level B

B1 = zxy - zmin
B2 = zxy - zmax
If B1 > 0 and B2 < 0, output zxy
Else output zmed

Median Filter and Adaptive Median Filter

Examples: Salt and pepper noise, MRI brain images
Median filter results: remove impulse noise
Adaptive median filter results: handle spatially dense impulse noise and provide smoothing

Other Filters

Max and Min Filters: example, Image corrupted by pepper noise with prob.= 0.1
Alpha-trimmed Mean Filter: formula, example, Image corrupted by additive uniform noise and salt-and-pepper noise
Adaptive Filter: general concept, more complex, superior performance, adaptive, local noise reduction filter

Mean Filters

Degradation model: g(x, y) = f(x, y) * h(x, y) + η(x, y)
Arithmetic mean filter or moving average filter
Geometric mean filter: formula
Harmonic mean filter, Contraharmonic mean filter

Order-Statistic Filters

Median filter
Max and min filters
Midpoint filter
Alpha-trimmed mean filter

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Description

Learn about the adaptive median filter and its ability to handle spatially dense impulse noise. Discover how the filter size changes depending on image characteristics.