python+opencv轮廓检测代码解析

import cv2 
 
#读入图片 
img = cv2.imread("1.png") 
 
# 必须先转化成灰度图 
gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY) 
 
# 二值化 
ret, thresh = cv2.threshold(gray, 127, 255, cv2.THRESH_BINAEY) 
 
# 寻找轮廓 
contours, hierarchy = cv2.findContours(thresh, cv2.RETR_TREE, cv2.CHAIN_APPROX_SIMPLE) 
 
# 画出轮廓，-1,表示所有轮廓，画笔颜色为(0, 255, 0)，即Green，粗细为3 
cv2.drawContours(img, contours, -1, (0, 255, 0), 3) 
 
# 显示图片 
cv2.namedWindow("Contours", cv2.NORMAL_WINDOW) 
cv2.imshow("Contours", img) 
 
# 等待键盘输入 
cv2.waitKey(0) 
cv2.destroyAllWindows()