15、OpenCV Python 轮廓发现

 __author__ = "WSX"
 import cv2 as cv
 import numpy as np
 # 基于拓扑结构来发现和绘制（边缘提取）
 # cv.findContours() 发现轮廓
 # cv.drawContours()  绘制轮廓
 # 使用梯度 ，不需要阈值了就

 def edge_demo(image):
     blurred = cv.GaussianBlur(image, (3, 3), 0)
     gray = cv.cvtColor(blurred, cv.COLOR_BGR2GRAY)
     # X Gradient
     xgrad = cv.Sobel(gray, cv.CV_16SC1, 1, 0)
     # Y Gradient
     ygrad = cv.Sobel(gray, cv.CV_16SC1, 0, 1)
     #edge
     #edge_output = cv.Canny(xgrad, ygrad, 50, 150)
     edge_output = cv.Canny(gray, 30, 100)
     cv.imshow("Canny Edge", edge_output)
     return edge_output

 def contours_demo(image):
     """dst = cv.GaussianBlur(image, (3, 3), 0)
     gray = cv.cvtColor(dst, cv.COLOR_BGR2GRAY)
     ret, binary = cv.threshold(gray, 0, 255, cv.THRESH_BINARY | cv.THRESH_OTSU)
     cv.imshow("binary image", binary)"""
     binary = edge_demo(image)

     cloneImage, contours, heriachy = cv.findContours(binary, cv.RETR_EXTERNAL, cv.CHAIN_APPROX_SIMPLE)
     # cv.RETR_EXTERNAL最大轮廓  CHAIN_APPROX_SIMPLE简单的
     #contours 放轮廓          heriachy层次信息
     for i, contour in enumerate(contours):
         cv.drawContours(image, contours, i, (0, 0, 255), 2)
         #绘制(0, 0, 255)颜色   2 为宽度       若为-1 则填充轮廓
         approxCurve = cv.approxPolyDP(contour, 4, True)
         if approxCurve.shape[0] > 6:
             cv.drawContours(image, contours, i, (0, 255, 255), 2)
         if approxCurve.shape[0] == 4:
             cv.drawContours(image, contours, i, (255, 255, 0), 2)
         print(approxCurve.shape[0])
         print(i)
     cv.imshow("detect contours", image)

 def main():
     img = cv.imread("1.JPG")
     cv.namedWindow("Show", cv.WINDOW_AUTOSIZE)
     cv.imshow("Show", img)

     contours_demo(img)
     cv.waitKey(0)
     cv.destroyAllWindows()

 main()