HoughLine.py

#HIGH PASS FILTERS can perform these actions:
# edge detection --> using Hough Line Transform

import cv2
import numpy as np
import matplotlib.pyplot as plt


def main():

	windowName = 'Hough Line Transform Method'

	cap = cv2.VideoCapture(0)

	if cap.isOpened():
		ret, frame = cap.read()
	else:
		ret = False	

	while ret:
		
		ret, frame = cap.read()
		
		gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)
		edges = cv2.Canny(gray, 50, 250, apertureSize=3, L2gradient=True)

		lines = cv2.HoughLines(edges, 1, np.pi/180, 150)
		
		if lines is not None:
			for rho, theta in lines[0]:
				a = np.cos(theta)
				b = np.sin(theta)
				x0 = a*rho
				y0 = b*rho
				pts1 = (int(x0 + 1000*(-b)), int(y0 + 1000*(a)))
				pts2 = (int(x0 - 1000*(-b)), int(y0 - 1000*(a)))
				cv2.line(frame, pts1, pts2, (0, 255, 0), 3)

		cv2.imshow(windowName, frame)

		if cv2.waitKey(1)==27:  # Exit on ESC
			break

	cap.release()	
	cv2.destroyAllWindows()
		

if __name__ == '__main__':
	main()