*Noise Removal* - ANS-*Noise removal for images*
- At local neighborhood
*Median filter*
- Good for salt-and-pepper noise
- Preserves edges
- Not separable
*Average filter*
- smooth image
- separable filter
*Gaussian filter*
- Weight influence of pixels by their distance to their center pixel
- Normal distribution
- Spread parameters
- Separable filter**
*Edge Detection* - ANS-*Interesting things happen at an edge*
- Object boundaries
*Look for derivatives/gradients in image*
- First and second derivatives/gradients
*Classic gradient operators*
- Sobel, Prewitt
- Gaussian derivatives
*Primary problem in edge detection is dealing with image noise*
- Smoothing and hysteresis thresholding
**Canny edge detector** (IMPORTANT!)
*Image Pyramids* - ANS-*Image pyramids as multi-resolution image representation*
- Gaussian pyramid
- Laplacian pyramid
*Two fundamental operations for pyramids*
- First operation blurs and samples the input
, - Second operation *interpolates* the blurred and sampled image to estimate the original
*Laplacian Error Pyramid*
- Error is difference between interpolated estimate and original
- Original signal can be recovered exactly by interpolating, then summing all the levels of the
error pyramid
- Can be represented very efficiently
*Useful for image coding/compression and progressive transmission*
*Gaussian pyramid useful for other tasks*
*2D Shape* - ANS-*Given a 2-D binary shape, use representations/properties to characterize
the region*
- Recognition or matching
*Methods*
- Chain code
- Quadtree
- Medial axis
- Bounding box, extremal points
- Area, centroid
- Perimenter, compactness, circularity
- Signatures
- Moments
Hough Transform
- Used to identify/represent shapes in images by searching all possible parameters
*PCA and Face Recognition* - ANS-*Reduce high-dimensional input to lowerdimensional
"sub-space"*
- Beneficial for recognition
*PCA offers linear approximation to the sub-space
which can be reduced to only the major sub-space
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller Hkane. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for £6.57. You're not tied to anything after your purchase.
