Finding lines in frames in OpenCV

find_lines_opencv.py

def find_lines(frame):
    gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)
    gray = cv2.GaussianBlur(gray,(5,5),0)
    # ret, gray = cv2.threshold(gray,190,255,cv2.THRESH_BINARY_INV)
    
    edges = cv2.Canny(gray, 30, 150, apertureSize = 3)
    # edges = cv2.Canny(gray, 50, 200, apertureSize = 3)
    
    lines = cv2.HoughLines(edges, 1, np.pi/180, 200)
    if lines is not None:
        for line in lines:
            # for rho,theta in lines[1]:
            for rho,theta in line:
                a = np.cos(theta)
                b = np.sin(theta)
                x0 = a*rho
                y0 = b*rho
                x1 = int(x0 + 1000*(-b))
                y1 = int(y0 + 1000*(a))
                x2 = int(x0 - 1000*(-b))
                y2 = int(y0 - 1000*(a))
            
                cv2.line(frame, (x1,y1), (x2,y2), (0,0,255), 2)   
     
    # lines = cv2.HoughLinesP(edges, 1, np.pi/180, 100, minLineLength=100, maxLineGap=10)    
    # if lines is not None:
    #   for line in lines:
    #         x1, y1, x2, y2 = line[0]
    #         cv2.line(frame, (x1, y1), (x2, y2), (255, 0, 0), 3)       
            
    frame = cv2.flip(frame, 1)            
    return frame