I’m trying to get the coordinate of every end point on every line, but i couldn’t come up with a solution, this is what I’ve currently got but its finding the outline of the lines not the lines itself
import cv2 import numpy as np img = cv2.imread('out copy.png') gray = cv2.cvtColor(img,cv2.COLOR_BGR2GRAY) kernel_size = 5 blur_gray = cv2.GaussianBlur(gray,(kernel_size, kernel_size),0) low_threshold = 50 high_threshold = 150 edges = cv2.Canny(blur_gray, low_threshold, high_threshold) rho = 1 # distance resolution in pixels of the Hough grid theta = np.pi / 180 # angular resolution in radians of the Hough grid threshold = 15 # minimum number of votes (intersections in Hough grid cell) min_line_length = 50 # minimum number of pixels making up a line max_line_gap = 20 # maximum gap in pixels between connectable line segments line_image = np.copy(img) * 0 # creating a blank to draw lines on # Run Hough on edge detected image # Output "lines" is an array containing endpoints of detected line segments lines = cv2.HoughLinesP(edges, rho, theta, threshold, np.array([]), min_line_length, max_line_gap) for line in lines: for x1,y1,x2,y2 in line: cv2.line(line_image,(x1,y1),(x2,y2),(0,255,0),5) lines_edges = cv2.addWeighted(img, 0.8, line_image, 1, 0) cv2.imshow('out copy.png', lines_edges) cv2.waitKey(0) ```
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Answer
The hit-or-miss transform can be used to find end points of a line after skeletonization.
Code:
img = cv2.imread('image.png') img2 = img.copy() gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY) # inverse binary image, to make the lines in white th = cv2.threshold(gray, 0, 255, cv2.THRESH_BINARY_INV + cv2.THRESH_OTSU)[1]
# obtain binary skeleton sk = cv2.ximgproc.thinning(th, None, 1)
# kernels to find endpoints in all 4 directions k1 = np.array(([0, 0, 0], [-1, 1, -1], [-1, -1, -1]), dtype="int") k2 = np.array(([0, -1, -1], [0, 1, -1], [0, -1, -1]), dtype="int") k3 = np.array(([-1, -1, 0], [-1, 1, 0], [-1, -1, 0]), dtype="int") k4 = np.array(([-1, -1, -1], [-1, 1, -1], [0, 0, 0]), dtype="int") # perform hit-miss transform for every kernel o1 = cv2.morphologyEx(sk, cv2.MORPH_HITMISS, k1) o2 = cv2.morphologyEx(sk, cv2.MORPH_HITMISS, k2) o3 = cv2.morphologyEx(sk, cv2.MORPH_HITMISS, k3) o4 = cv2.morphologyEx(sk, cv2.MORPH_HITMISS, k4) # add results of all the above 4 out = o1 + o2 + o3 + o4 # find points in white (255) and draw them on original image pts = np.argwhere(out == 255) for pt in pts: img2 = cv2.circle(img2, (pt[1], pt[0]), 15, (0,255,0), -1)