Background subtraction
19 important questions on Background subtraction
What two properties do we expect/assume a background to have?
Four challenges of background subtraction based on reference model (background image)
- Movement
- Shadows
- Color variations/overlap
- Aliasing
How is color variations a challenge in background subtraction?
The model cannot distinguish foreground from background
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How is color overlap a challenge in background separation?
The model cannot distinguish side-effects from foreground
Name a challenge of outdoor background separation
Model incorrectly assumes foreground appears yet it is just that light is changed
What is a challenge of background separation of a sailing boat?
What is image aliasing?
How can image aliasing be a problem for background subtraction?
These changes might be slight, yet as well large near edges of highly discrepanzing pixels.
This inconsistently resolves in incorrect separation with naïve separation.
What is the reference image in a background subtraction task?
How does the naïve background subtraction technique work?
Label the pixel foreground in case a threshold delta is succeeded/surpassed?
What are the two basic techniques for noise reduction in background subtraction?
How does erosion work?
If the number of active neighbors is heigher than a threshold, the pixel is maintained active.
When to apply erosion in a background subtraction task?
How does dilation work?
If a certain threshold of active neighbors is surpassed, activate that pixel
How to adapt (improve) for slightly changing background colors?
Use a Gaussian (normal) distribution with larger standard deviation.
In background subtraction, why do pixels of the reference image near edges have a higher deviation?
In background subtraction, why do pixels of the reference image that are brighter have a larger standard deviation?
(Yet I assume in consideration of Hue for HSV, or CIElab this will not be the case, rather inverse???...)
What is a Gaussian Mixture Model?
Why use a mixture of Gaussian models for background subtraction?
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