How to detect the circular object in the middle of this image?

I have a binary image. I want to keep the circular object in the middle of the image and remove all other components. How can I do that?

Answer 1

[Image Analyst]

Simply mask the image. See attached m-file.

[Rafi Ahmed]

Hi,

How can you measure the pixels of the masked portion? It is variable. It could be located in upper or lower portion or right side of the image. Is there any way to measure the pixels according to the position of the circular object? I have attached two different image with different positions.

[Image Analyst]

I suggest using normxcorr2() to find the pattern. I attach an example.

[Rafi Ahmed]

Thanks for your help.