python - How to draw a line on an image in OpenCV?

Question

If I have the polar coordinates of a line, how can I draw it on an image in OpenCV & python?

Line function takes 2 points, but draws only the segment. I want to draw a line from one edge of the image to other.

question from:https://stackoverflow.com/questions/18632276/how-to-draw-a-line-on-an-image-in-opencv

Answer 1

Just calculate for 2 points outside. opencv's Line is fine with e.g. (-10,-10) for a point.

import cv2  # python-opencv
import numpy as np

width, height = 800, 600
x1, y1 = 0, 0
x2, y2 = 200, 400
image = np.ones((height, width)) * 255

line_thickness = 2
cv2.line(image, (x1, y1), (x2, y2), (0, 255, 0), thickness=line_thickness)

http://docs.opencv.org/2.4/modules/core/doc/drawing_functions.html#cv2.line