How to isolate the circle from the shaded area?

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Mahmoud 2015-2-1

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/174282-how-to-isolate-the-circle-from-the-shaded-area

编辑： Matt J 2015-2-1

I would like to have only a shaded area from the picture. I want to remove the circle from the binary image. Any idea?

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Answer 1

Matt J 2015-2-1

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https://ww2.mathworks.cn/matlabcentral/answers/174282-how-to-isolate-the-circle-from-the-shaded-area#answer_166648

在 MATLAB Online 中打开

How about

       A=imread('http://www.mathworks.com/matlabcentral/answers/uploaded_files/24735/D1.png');
       A=rgb2gray(A);
       outer=~imfill(A,'holes'); 
       outerd=imdilate(outer,ones(5));
      newImage = A&~outerd;

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Mahmoud 2015-2-1

Amazing!! That worked perfectly! Now, if I want to fill the isolated area to find the area in pixel using regionprops, how can I fill that region?

Matt J 2015-2-1

编辑：Matt J 2015-2-1

在 MATLAB Online 中打开

    B=imerode(~A,ones(3));
    S=regionprops(B,'PixelIdxList','Area');
    [ar,idx]=sort([S.Area],'descend');
    tofill=vertcat(S(idx(1:2)).PixelIdxList);
     C=false(size(A));
     C(tofill)=1; 
     result=~imdilate(C,ones(5));