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What is the meaning of a junction point in image skeleton ? I am using opencv and c++ to develop a code source to detect the main local junction point in the image .Many thanks in advace .

user138957
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2 Answers2

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A junction point is usually the intersection of two lines. See this image:

https://docs.google.com/file/d/0ByS6Z5WRz-h2U3NBWWZ6V3FqeUk/edit?pli=1

Skeleton refers (usually) to the skeletonization of an image. this article is useful:

http://en.wikipedia.org/wiki/Topological_skeleton.

So I think what they are asking you do is, to take the image find its skeleton then figure out which pixel contain the intersection of the lines of the skeleton.

Skeletonization in opencv

Community
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Matt Johnson
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  • Thank you for your fast answer .Please , have you any idea how can I find the junction point if it is the intersection between two curve edge in the skeleton ? – user138957 May 08 '13 at 19:06
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isn't it as simple as:

a junction has 2 or more neighbour pixels of the same color

?

berak
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  • Thank you for your answer . Please could you provide me with an example or algorithm ?I am currently working with binary image – user138957 May 08 '13 at 19:19
  • Consider a matrix N= [p9 p2 p3; p8 p1 p4; p7 p6 p5] Array A= [p9 p8 p7 p6 p5 p4 p3 p2] Array B=[p8 p7 p6 p5 p4 p3 p2 p9] S=sum(abs(A-B)) Condition on the pixel to be - A junction point : (p1==1)&&(S>=6)///My problem is how to detect the main junction - An free point : (p1==1)&&(S==2) – user138957 May 08 '13 at 19:29
  • int same = (p9==p1); same += (p8==p1); same += (p7==p1); .... bool junction = same >=2; – berak May 08 '13 at 19:37