![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/179808/image.bmp)
How to find the circle in image?
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Hello,
I have an image and I am unable to extract the circle in it. I have used all the methods including regionprops, imfindcircles and much more.
Can you kindly tell how I can make the whole circular region white and the rest of the image black?
Best Regards.
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/170617/image.png)
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回答(1 个)
KSSV
2017-12-5
YOu can try the below code. I have attached the result image and the function used. YOu can reduce the Radius the radius of circle, if you want.
I = imread('image.png') ;
I = rgb2gray(I) ;
figure(1)
imshow(I)
%%GEt the white regions
[y,x] = find(I) ;
%%Fit a circle
[xc,yc,R,a] = circfit(x,y) ;
%%If you want reduce the Radius by some fraction
% R = R-15 ;
th = linspace(0,2*pi) ;
xi = xc+R*cos(th) ; yi = yc+R*sin(th) ;
%%Get indices lying inside the circle
[ny,nx] = size(I) ;
[X,Y] = meshgrid(1:nx,1:ny) ;
idx = inpolygon(X(:),Y(:),xi,yi) ;
I(idx) = 255 ;
figure(2)
imshow(I)
Result:
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/179808/image.bmp)
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