python+opencv识别图片中的圆形

# -*- coding: utf-8 -*- 
""" 
Created on Tue Sep 26 23:15:39 2017 
 
@author: tina 
""" 
import cv2 
import numpy as np 
import matplotlib.pyplot as plt 
 
img = cv2.imread('C:\\Users\\tina\\Pictures\\ahh\\ball.jpg') 
gray = cv2.cvtColor(img,cv2.COLOR_BGR2GRAY) 
 
plt.subplot(121),plt.imshow(gray,'gray') 
plt.xticks([]),plt.yticks([]) 
 
circles1 = cv2.HoughCircles(gray,cv2.HOUGH_GRADIENT,1, 
600,param1=100,param2=30,minRadius=80,maxRadius=97) 
circles = circles1[0,:,:] 
circles = np.uint16(np.around(circles)) 
for i in circles[:]: 
 cv2.circle(img,(i[0],i[1]),i[2],(255,0,0),5) 
 cv2.circle(img,(i[0],i[1]),2,(255,0,255),10) 
 cv2.rectangle(img,(i[0]-i[2],i[1]+i[2]),(i[0]+i[2],i[1]-i[2]),(255,255,0),5) 
 
print("圆心坐标",i[0],i[1]) 
plt.subplot(122),plt.imshow(img) 
plt.xticks([]),plt.yticks([])