title: HoughCircles circle detection using opencv and python-
body: <p>I am trying to use OpenCV's (Hough)Circle detection to.. detect circles. I created a solid circle on a black background, tried to play with the parameters, used blur and everything, but I am just not able to make it find anything. </p>
  
  <p>Any ideas, suggestions etc. would be great, thank you!</p>
  
  <p>my current code is something like this:</p>
  
  <pre><code>import cv2
  import numpy as np
  
  """
  params = dict(dp=1,
                minDist=1,
                circles=None,
                param1=300,
                param2=290,
                minRadius=1,
                maxRadius=100)
  """
  
  img = np.ones((200,250,3), dtype=np.uint8)
  for i in range(50, 80, 1):
      for j in range(40, 70, 1):
          img[i][j]*=200
  
  cv2.circle(img, (120,120), 20, (100,200,80), -1)
  
  
  gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
  canny = cv2.Canny(gray, 200, 300)
  
  cv2.imshow('shjkgdh', canny)
  gray = cv2.medianBlur(gray, 5)
  circles = cv2.HoughCircles(gray, cv2.cv.CV_HOUGH_GRADIENT, 1, 20,
                param1=100,
                param2=30,
                minRadius=0,
                maxRadius=0)
  
  print circles
  circles = np.uint16(np.around(circles))
  for i in circles[0,:]:
      cv2.circle(img,(i[0],i[1]),i[2],(0,255,0),2)
      cv2.circle(img,(i[0],i[1]),2,(0,0,255),3)
  
  cv2.imshow('circles', img)
  k = cv2.waitKey(0)
  if k == 27:
      cv2.destroyAllWindows()
  </code></pre>