# how to calculate the diameter of a vessel

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bil bbil on 17 Apr 2014
Commented: bil bbil on 20 Apr 2014
hello everyone
I really need help as soon as possible
I want a solution to calculate the diameter of each white line in the image(Vessel Diameter Measurement)

#### 1 Comment

John D'Errico on 17 Apr 2014
Compute the radius. Multiply by 2.
Really, we are not here to do your homework as soon as possible. IF you could not start it in a timely way, then why should we rush?
Make an effort, as that is the way to learn. Or don't make an effort. In that case, learn to say the phrase "Do ya want fries with that order?"

Sean de Wolski on 17 Apr 2014
You might find the second part of this webinar helpful:

Nitin on 17 Apr 2014
I would start by first experimenting with regionprops function in matlab

#### 1 Comment

bil bbil on 17 Apr 2014
you have an idea how to fit in my case??

Image Analyst on 17 Apr 2014
Edited: Image Analyst on 17 Apr 2014
It's pretty easy - maybe 3 lines of code. First call bwdist to get the distance from the white pixels to the nearest black pixel. Then call bwmorph to skeletonize that so you get the distances along the centerlines. That's the radius so multiply by two to get the diameter. It will be an image looking like a skeleton and to find the diameter you simply look at the value of the pixel at the location you want the diameter of. Basically it's this (untested):
edtImage = 2 * bwdist(~binaryImage);
skeletonImage = bwmorph(binaryImage, 'skel', inf);
diameterImage = edtImage * double(skeletonImage);
Can't get much simpler, though you may want to add a utility where you let the user call ginput() to report back the diameter at the closest pixel to where they clicked. It's pretty easy, though clever and not obvious (until you know about it), so most novices might embark on some complicated looping process to get cross sections (what a nightmare that would be).