What are exactly the "r min" and "r max" in "imfindcircles"?

When I use the range [20 80], the maximum found radius is around 50. But, when I increase the range to [20 20000], the maximum found radius is around 80? So, why the circles with the radius around 80 are not found by the first range?

[EDITED] This is the code: [centers1,radii1] = imfindcircles(edges_gray,[20 80]);

The maximum radius for [20 80] is 50.45 The maximum radius for [20 100] is 50.46 The maximum radius for [20 20000] is 98.48

These are the results from the last run.

I guess the elements in this range are not the minimum and the maximum radius. Because, when I set the range [60 100], no circle is found, while I set the range [20 20000], the there are a lot of radii between 60 and 100. I attached the input image.

Answer 1

[Image Analyst]

I think I remember that this was a known bug in some prior version. I believe I notified Jeff on the Image Processing tea of it.

[Shahin Safazadeh]

I'm using MATLAB 2017!