Eigenvalue based blob detector

In summary, the principle of centrality involves looking at how people or entities are connected to each other in a network, represented by an NxN matrix. The Adjacency Matrix is a specific type of matrix that can show the strength of relationships between individuals. Higher eigenvector centrality indicates stronger connections. This concept may not translate well to image analysis as it does not take into account spatial relationships. Other methods may be more suitable for feature detection in images.
  • #1
NotASmurf
150
2
Hey all, I just read up on the principle of centrality, where

"Think of a "network" as an NxN matrix, which has information about how N people (or N pages or N countries..) are connected to each other.

Adjacency Matrix is an NxN matrix, let's say it looks something like this. People who aren't connected to each other have A[j] = 0, people with weak relationships have A[j] = 0.1, people with medium ties have A[j]=0.4,
people with strong ties have A[j] = 0.6
1---2----3----4
1---0.0 0.1 0.4 0.6
2---0.1 0.0 0.4 0.0
3---0.4 0.4 0.0 0.1
4---0.6 0.0 0.1 0.0

1 and 2 are weakly connected, 1 and 3 have medium ties, 1 and 4 have strong ties. This is just a quick example to give you a quick idea. These matrices may not always be symmetric either.

People with "higher eigenvector centrality" are people who are better connected to each other. This takes into account, not just how many people the person knows, but also whom the person knows.'

Is it feasible to use this to locate blobs in images using their color relations to each other? I need a feature detector/ blob extractor that doesn't use corners so I saw this. Any advice appreciated.
 
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  • #2
How do you plan to use it? The eigenvectors don't care about order, so the concept of "being next to each other" (which is relevant if you look for features) doesn't translate well to the matrix problem.
 
  • #3
What is the final goal ? Send a picture, i will see if there is no simpler method.
The method you are explaining need to compute eigen vector of a sparse matrix of size PixelNumber * PixelNumber. You can use préconjugate gradient but it's not easy.
 

Related to Eigenvalue based blob detector

1. What is an eigenvalue based blob detector?

An eigenvalue based blob detector is a computer algorithm that is used to detect and locate circular and elliptical objects in an image. It works by analyzing the eigenvalues of the Hessian matrix at different points in the image, which can indicate the presence of a blob-like structure.

2. How does an eigenvalue based blob detector work?

The algorithm first calculates the Hessian matrix for the image, which is a matrix of second-order derivatives. Then, the eigenvalues of this matrix are calculated at different points in the image. Locations with high positive values of the eigenvalues are considered as potential blob centers, and the size and shape of the blob can be estimated based on the scale and orientation of the eigenvectors.

3. What are the advantages of using an eigenvalue based blob detector?

One major advantage is that it is relatively fast and efficient, making it suitable for real-time applications. It is also robust to noise and variations in lighting conditions. Additionally, it can detect blobs of different sizes and shapes, making it versatile for various image analysis tasks.

4. What are the limitations of an eigenvalue based blob detector?

One limitation is that it may struggle with detecting blobs of similar sizes that are close together or overlapping. It also requires a predefined scale and orientation, which may not always be known or easy to determine. Additionally, it may not work well on images with complex backgrounds or with a high number of blobs.

5. What are some applications of an eigenvalue based blob detector?

Eigenvalue based blob detectors are commonly used in computer vision and image processing tasks, such as object detection and recognition, feature extraction, and medical imaging. They can also be used in industrial applications, such as quality control and inspection, as well as in satellite and aerial imagery analysis.

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