Adaptive Median Filtering
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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?

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

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

    <p>To remove only impulse noise from the image</p> Signup and view all the answers

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

    <p>To output the final filtered pixel value</p> Signup and view all the answers

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

    <p>Pepper noise</p> Signup and view all the answers

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

    <p>It adapts to local image characteristics</p> Signup and view all the answers

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

    <p>To remove multiple types of noise from an image</p> Signup and view all the answers

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

    <p>The median filter is more resistant to outliers</p> Signup and view all the answers

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

    <p>The noise is reduced</p> Signup and view all the answers

    What is the primary application of a median filter?

    <p>Noise reduction</p> Signup and view all the answers

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

    <p>To remove different kinds of noise</p> Signup and view all the answers

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

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

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

    <p>Median filter</p> Signup and view all the answers

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

    <p>It can adapt to the local noise characteristics</p> Signup and view all the answers

    What is the formula for the arithmetic mean filter?

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

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

    <p>The arithmetic mean filter is more suitable for image smoothing</p> 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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    Quiz Team

    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.

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