局部处理的边缘连接（python+opencv）

import cv2
import numpy as np

path = "_lo.png"
img = cv2.imread(path)
gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
gray = gray / 255.0 #像素值0-1之间

#sobel算子分别求出gx，gy
gx = cv2.Sobel(gray, cv2.CV_64F, 1, 0, ksize=3)
gy = cv2.Sobel(gray, cv2.CV_64F, 0, 1, ksize=3)
mag, ang = cv2.cartToPolar(gx, gy, angleInDegrees=1) #得到梯度幅度和梯度角度阵列
g = np.zeros(gray.shape) #g与图片大小相同

#行扫描，间隔k时，进行填充，填充值为1
def edge_connection(img, size, k):
    for i in range(size):
        Yi = np.where(img[i, :] > 0)
        if len(Yi[0]) >= 10: #可调整
            for j in range(0, len(Yi[0])-1):
                if Yi[0][j+1] - Yi[0][j] <= k:
                    img[i, Yi[0][j]:Yi[0][j+1]] = 1
    return img

#选取边缘，提取边缘坐标，将g中相应坐标像素值设为1
X, Y = np.where((mag > np.max(mag) * 0.3)&(ang >= 0)&(ang <= 90))
g[X, Y] = 1

#边缘连接，此过程只涉及水平，垂直边缘连接，不同角度边缘只需旋转相应角度即可
g = edge_connection(g, gray.shape[0], k=20)
g = cv2.rotate(g, 0)
g = edge_connection(g, gray.shape[1], k=20)
g = cv2.rotate(g, 2)

cv2.imshow("img", img)
cv2.imshow("g", g)
cv2.waitKey(0)