FAQ Database Discussion Community


Doing topological sort using strongly connected components to find cycles (digraph)

algorithm,topological-sort,connected-components
From the little I understand, one way of doing topological sorting if you have a readymade efficient black-box method for strongly connected components would be: (assumption - no self loops) run strongly connected components if you have one or more components of size > 1 then this graph has cycles....

Error while calculating the edge of an image

matlab,image-processing,edge-detection,mathematical-morphology,connected-components
I'm trying to extract edge from an image. I used the following algorithm.Input image(e11) which is a 512 * 512 grayscale image is also given. Find the morphological gradient of input image(gradientim) Find the negative image of the gradient image(negativeim) Subtract original image from the closed image using bottom-hat transformations(bottomhatim)....

get connected components using igraph in R

r,graph,igraph,connected-components
I would like to find all the connected components of a graph where the components have more than one element. using the clusters gives the membership to different clusters and using cliques does not give connected components. This is a follow up from multiple intersection of lists in R My...

Split image containing multiple, irregularly shaped images in Python

python,image,image-processing,connected-components
Given an image that contains several irregularly sized and shaped images (shown here as circles for the sake of simplicity): ...how can I: Detect sub-images Split and save sub-images as separate files? Ideally I'm looking for a python solution. I've tried "connected component analysis" algorithms, and centroid measurement but the...

R / SQL /Python : Extracting connected components from node-edge pairs

python,sql,r,graph,connected-components
I struggle to come up with a title that describes what I'm trying to solve, so please comment if you have a better title! The solution can be in R, Python, or SQL (Aster TeraData SQL to be exact, though a solution any SQL language is very helpful for learning...

connected component analysis error

matlab,image-processing,connected-components
I'm trying to do connected component analysis.but I'm getting error. I need the vertebral body ;but I'm getting some other objects. Image is: http://i58.tinypic.com/s4yu00.jpg. Result is: http://i62.tinypic.com/2ujld74.jpg im= imread('im.bmp'); figure,imshow(im); K1=imadjust(im); figure, imshow(K1), title('After Adjustment Image') threshold = graythresh(K1); originalImage = im2bw(K1, threshold); originalImage = bwareaopen(originalImage,100); se = strel('disk', 2);...

Error in using detectMSERFeatures

matlab,image-processing,matlab-cvst,connected-components
I was trying to do some morphological operation and then tried detectMSERFeatures. I'm getting error.can you suggest any alternative/correction in the code.The error I had in the matlab is also quoted Img= imread('sub.png'); figure,imshow(Img);title('Original Image') Img=double(Img); m1=Img>40; sd = stdfilt(Img, ones(3,3)); Img = Img.*m1; figure,imshow(Img); Img = bwareaopen(Img,50); figure,imshow(Img); %...