# What are (r min) & (r max) in "imfindcircles"?

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댓글: Shahin Safazadeh 2018년 4월 13일
To count some cells in an image, I set the radii range [20 80] in "imfindcircles" and around 70 circles were found with the largest radius < 60. After changing the radii range to [20 2000], more than 120 circle were found with the largest radius < 80! I don't understand if the largest radius is <80, why is it not found by setting the first range [20 80]?
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편집: Shahin Safazadeh 2018년 4월 2일
subplot(2,2,3),imshow(img),title('Found cells')
hold on
img_gray = rgb2gray(img);
subplot(2,2,1),imshow(img_gray), title('RGB to gray conversion')
edges_gray = edge(img_gray,'Canny');
subplot(2,2,2),imshow(edges_gray), title('Edges by Canny')
Image Analyst 2018년 4월 2일
You forgot to attach 'D:\KUL\CV\assignment\assignment_2\circles_on_original_img.png' and 'D:\KUL\CV\assignment\assignment_2\normal.jpg'.

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### 답변 (2개)

Abhishek Ballaney 2018년 4월 2일
https://in.mathworks.com/help/images/ref/imfindcircles.html
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Suraj Mankulangara 2018년 4월 13일
Hello Shahin,
I suspect that this is an accuracy issue. The recommendation from MathWorks is that for best results, the conditions rmax < 3*rmin and (rmax-rmin) < 100 should hold:
https://in.mathworks.com/help/images/ref/imfindcircles.html#Tips
It could very well be that "imfindcircles" fails since these conditions are not met when the radius range is specified as [20, 2000]
- Suraj Mankulangara
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Hi Suraj,
Seeing the warning in MATLAB, I already realized that I should respect those 2 conditions. Although, MATLAB can't find all the circles within the interval, when I set the interval, [20 80]! On the other hand, increasing the interval takes too long to get the result. So, I believe, this syntax is not that useful for counting cells.

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