SMI Tomasi corner detection - Python(OpenCV)

import numpy as np
import cv2 as cv

img = cv.imread('pic1.png')
gray = cv.cvtColor(img, cv.COLOR_BGR2GRAY)
corners = cv.goodFeaturesToTrack(gray, 25, 0.01, 10)
corners = np.int0(corners)

for i in corners:
    x, y = i.ravel()
    cv.circle(img, (x,y), 3, 255, -1)

cv.imshow('dat', img)

if cv.waitKey(0) & 0xff == 27:
    cv.destroyAllWindows()