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

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Ashkan Javadzadegan 2015-4-15

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评论： Ashkan Javadzadegan 2015-4-16

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

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pfb 2015-4-15

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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);

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pfb 2015-4-15

编辑：pfb 2015-4-16

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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