how do i label objects in an image which is quite unclear? When i make it bw, objects overlapping get labelled as a single object. I want to be able to call each object seperately.

It's a snapshot of a microchannel part of an experiment that I am working on. I want to find the number of bubbles and surface area of each bubble. Please Help

Answer 1

[Ahmet Cecen]

Look up circular Hough transform.

https://en.wikipedia.org/wiki/Circle_Hough_Transform

http://www.mathworks.com/help/images/ref/imfindcircles.html

Answer 2

[Image Analyst]

Do you mean like this:

If so, then see the attached m-file, which will produce the image above.

You can also get the equivalent circular diameter as well as the area if you ask regionprops for 'EquivDiameter'.

If you want the filled area of the black rings, then that will require a slight modification. Let me know if you need that.

[KG Srinidhi]

Yes i need the filled area with the black rings. Thanks a lot

[Image Analyst]

Sorry - I don't have time now to do it. But you need to change the threshold to instead of >50. Then you need to split apart the bubbles because many of the rings are melded together quite a bit. So you can see this: <http://blogs.mathworks.com/steve/2013/11/19/watershed-transform-question-from-tech-support/ for instructions on how to separate them. imfindcircles might be easier but I don't know how well it copes with touching circles and how accurate the diameter is with respect to the actual area - you'd just have to try it and see. Check out the video on Brett's tutorial: http://www.mathworks.com/matlabcentral/fileexchange/34365-circle-finder

[KG Srinidhi]

imfindcircles was my first approach. It gave me correct values for number of bubbles. But the radii were of the smaller circle excluding the dark ring.Anyways thanks for the help!

[Image Analyst]

Then you'll have to do it like I suggested by changing the threshold to <50, then using the steps detailed in Steve's blog to split apart bubbles that are touching.