Define a curve in terms of (X,Y) values

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Ashkan Javadzadegan
Ashkan Javadzadegan am 15 Apr. 2015
Dear all,
I detected an artery borderline (Image B) on a grayscale image (image A). Now I would like to define the detected borderline in terms of (X,Y) values.
Would be much appreciated if any body could give me a hint. Ashkan

Antworten (1)

pfb
pfb am 15 Apr. 2015
I assume that B is in a single matrix. The light point should then correspond to matrix elements above some threshold. If this is the case, it should be sufficient to do this
[y x] = find(B>t);
  5 Kommentare
pfb
pfb am 15 Apr. 2015
Bearbeitet: pfb am 16 Apr. 2015
Well, that should not be that hard.
[Y,X] = size(B);
Gives you the size of the image in the vertical and horizontal direction (in pixels). You should know what that is in mm.
The "origin" is then
o = [X/2 Y/2];
Use round() if your matrix has odd dimensions and you want integer numbers.
Then
x = x-o;
y = y-o;
Again, these coordinates are "in pixels", but if you know the scale of the image it is easy to get the correct values. If Sx and Sy are the dimensions of the image in mms then
x = Sx/X*x;
y = Sy/Y*y;
Why your 3D model design software should care about where the origin of the axes is?
Ashkan Javadzadegan
Ashkan Javadzadegan am 16 Apr. 2015
Thanks, I will try this and will let you know ...

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