Vein Detection in Angiogram image

There are veins in above image. I need to find out the location of pixels at which veins are present.

I tried to do this:

img=imread('segmented plus orignal image 1\aa00001.jpg');
bi=im2bw(img); imshow(bi)

But still, it is not clear.

[Matthew Eicholtz]

What do you mean by "it is not clear"? Is this the result you get?

[Explorer]

Yes, I am getting this result. I want to remove other things. Only veins should be there.

Answer 1

[Matthew Eicholtz]

You may want to try edge detection followed by some image morphological operations (e.g. dilation, erosion) and region flood-filling.

Also, if your results from im2bw are as depicted in the comment above, the bwareaopen function may be helpful.

Answer 2

[Image Analyst]

Has that image already been through a Hessian or Frangi filter?

[Explorer]

Don't know.

[Image Analyst]

You should be able to find plenty of vessel tracking papers here: http://www.visionbib.com/bibliography/contentsmedical.html#Medical%20Applications,%20CAT,%20MRI,%20Ultrasound,%20Heart%20Models,%20Brain%20Models