title: Emgu CV:using HoughCircles detect many nonexistent circles,and waiting for long time
body: <p>original picture<br>
  <a href="https://i.stack.imgur.com/yzSCL.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/yzSCL.png" alt="original picture"></a>
  result picture
  <a href="https://i.stack.imgur.com/OH936.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/OH936.png" alt="result picture"></a></p>
  
  <p>Here is my code:</p>
  
  <pre><code>private void button3_Click(object sender, EventArgs e)
  {
      string strFileName = string.Empty;
      OpenFileDialog ofd = new OpenFileDialog();
      if (ofd.ShowDialog() == DialogResult.OK)
      {
          Image&lt;Bgr, byte&gt; img1 = new Image&lt;Bgr, byte&gt;(ofd.FileName);
          pictureBox1.Image = img1.ToBitmap();
          Image&lt;Gray, Byte&gt; gray1 = img1.Convert&lt;Gray, Byte&gt;().PyrUp().PyrDown();
  
          CircleF[] circles = gray1.HoughCircles(
          new Gray(150),
          new Gray(100),
          2,
          10,
          0,
          0)[0];
          Image&lt;Bgr, byte&gt; imageCircles = img1.CopyBlank();
          foreach (CircleF circle in circles)
          {
              imageCircles.Draw(circle, new Bgr(Color.Yellow), 5);
          }
          pictureBox4.Image = imageCircles.ToBitmap();
      }
  }
  </code></pre>
  
  <p>Are my parameters set correctly? Is there something I'm not understanding correctly?
  Thank you!</p>