title: Detect circular segment in the image
body: <p>I am trying to determine the circle parameters, using its slice, visible in the image. I want to know the radius, coordinates of center and draw the full circle (on the bigger picture of course). I've tried to use <strong>imfindcircles</strong> with Hough Transformation. Unfortunately, it looks like the slice of the circle is not big enough, and the algorithm does not recognize it as the full circle.</p>
  <p><a href="https://i.stack.imgur.com/hIxWq.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/hIxWq.jpg" alt="The fragment of white circle on black background" /></a></p>
  <pre><code>clear all;
  close all;
  
  figure();
  image = imread('circle3.jpg');
  imshow(image);
  
  Rmin = 10;
  Rmax = 10000;
  
  [centersBright, radiiBright] = imfindcircles(image,[Rmin 
  Rmax],'ObjectPolarity','bright','Method','TwoStage','Sensitivity',0.98,'EdgeThreshold',0.9);
  
  viscircles(centersBright, radiiBright,'Color','b');
  </code></pre>
  <p>I have changed the sensivity, threshold, Rmin, Rmax, even the method, but still, nothing happens. How can I detect this circle, if not in Matlab, then maybe in Python?</p>