MATLAB: How to delete the area around a circle in an image

Question

I have an image which has many circles in it, I've used viscircles to identify and draw a circle around the circles in the image. My next step is to delete the area around the circles, do you guys know how I could go about this???

Thank you so much

Answer 1

Yes. viscircles() does not find circles though - perhaps you meant imfindcircles().

I don't have your code so I can't extend it so I'll just give you the steps.

1. Use strel() to construct a disc structuring element
2. Use imdilate() to dilate your binary image (circles mask) to enlarge the circles
3. Use ringMask = xor(mask, dilatedMask) to get the annular mask.
4. Use the annular mask to set the gray scale image to 0 there: grayImage(ringMask) = 0;

Attach your image and code to produce the circles if you can't do it.