In this tutorial, we will create a harris corner detector to detect an image using cv2.cornerHarris() in python opencv.

1.Import library

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

2.Open an image as grayscale

image_bgr = cv2.imread('images/plane_256x256.jpg')
image_gray = cv2.cvtColor(image_bgr, cv2.COLOR_BGR2GRAY)
image_gray = np.float32(image_gray)

3.Set corner detector parameters

block_size = 2
aperture = 29
free_parameter = 0.04

4.Create  harris corner detector using cv2.cornerHarris()

detector_responses = cv2.cornerHarris(image_gray, block_size, aperture, free_parameter)

5.Mark corners

# Large corner markers
detector_responses = cv2.dilate(detector_responses, None)

# Only keep detector responses greater than threshold, mark as white
threshold = 0.02
image_bgr[detector_responses > threshold * detector_responses.max()] = [255,255,255]

7.Display image

image_gray = cv2.cvtColor(image_bgr, cv2.COLOR_BGR2GRAY)

# Show image
plt.imshow(image_gray, cmap='gray'), plt.axis("off")
plt.show()

Run this code, you may see this image: