imfindcircles doesn't work
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The image looks normal with range from 0 to 4096:
[x,y] = size(AA1); % output x and y both 512
Obviously radius range is [x/4 x/2].
However, both of below:
[centers, radii, metric] = imfindcircles(AA1,[fix(x/4) fix(x/2)],'ObjectPolarity','bright')
[centers, radii, metric] = imfindcircles(AA1,[fix(x/4) fix(x/2)])
output:
centers = []
radii = []
metric = []
changed to [x/6 x/2] doesn't help.
Thank you for finding the issue!
3 个评论
Image Analyst
2025-6-29
Are you trying to find the mask, which would be the overall circle, or circles inside the circular area? Please indicate what circles you expect to find. Obviously the overall mask could be found by thresholding:
maskBoundary = bwboundaries(AA1 > 0);
If you want circles within that, your data is too blurry and indistinct to find with imfindcircles. You'll have to use a different method to find whatever it is you expect to find in that blurry image.
Also, size() returns [rows, columns] and it's convention to have x be horizontal - the opposite of what you have. You have x as rows (vertical) and y as columns (horizontal dimension) which is the opposite of convention though in this case since they're both 512 it doesn't make any different. Nonetheless, to be less confusing, you should choose descriptive variable names, like
[rows, columns, numberOfColorChannels] = size(grayImage);
John
2025-6-29
Even made it binary:
AAB = zeros(size(AA1));
AAB(AA1>max(AA1(:))/2) = 1;
figure;imshow(AAB,[])
it showed a great binary circle:
[centers, radii, metric] = imfindcircles(AAB,[for all ranges])
Output still is:
centers = []
radii = []
mtric = []
Image Analyst
2025-6-30
If you have any more questions, then attach your image and code to read it in with the paperclip icon after you read this:
采纳的回答
hello
let's try with your image
AA = imread('circle.png');
AA = rgb2gray(AA);
BW = imbinarize(AA);
[B,L,N] = bwboundaries(BW);
whos
figure;imshow(BW)
hold on
%Display object boundaries in red and hole boundaries in green.
N
for k=1:length(B),
boundary = B{k};
if(k > N)
plot(boundary(:,2), boundary(:,1), 'g','LineWidth',2);
else
plot(boundary(:,2), boundary(:,1), 'r','LineWidth',2);
end
end
[m,n] =size(BW);
[centers,radii]=imfindcircles(BW,round([n/4,n/2]))
3 个评论
Mathieu NOE
2025-7-4
hello again @John
problem solved ?
help visboundaries
Mathieu NOE
2025-7-6
hello @Image Analyst
tx for the info, I'll try to remember
as you already know , I am not truly an image expert , that's not my every day job
I'm sometimes trying to improve my basic skills in that field
don't be surprised if my answers are still a bit "basic"
更多回答（1 个）
I can't reproduce the problem you claim to have with a binarized disk. That case is pretty well-handled by imfindcircles:
n=300;
[x,y]=deal(1:n);
mask=hypot(x-mean(x),y'-mean(y))<=n/3;
[centers,radii]=imfindcircles(mask,[n/4,n/2])
imshow(mask,[])
viscircles(centers,radii);
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