How to find if a binary image has some black areas with white holes?

Hi. I have a binary image with a black circle. Inside black circle there is a white cicle. How to find if this my binary image has black elements with a hole inside an element?

I used bwlabel, but don't know what to do with it next

[Image Analyst]

What is that? A black "element" with a hole in it would be a black region with a white blob in it. Generally black is considered background and white is considered foreground. If you have a white background and black blobs in it and some of the black blobs have white "holes" in them then you'd need to invert your image before doing what Walter says. Otherwise you can just call imclearborder (to get rid of the white background your black circle is sitting on) and see if the sum of the remaining image is greater than zero.

Answer 1

[Walter Roberson]

regionprops() the Euler Number

[Michael Shapira]

Thank you. I did as you suggested and extracted the black object

But I have now a new problem, how do I now that it actually has a hole inside. Because , white object can be a line that actually crosses the black object

[Image Analyst]

So you have like two half circles? That would be a black disc with a line cutting across it. How is that a hole? You should post your image somewhere. See http://www.mathworks.com/matlabcentral/answers/7924-where-can-i-upload-images-and-files-for-use-on-matlab-answers