cv2/numpy

[d8a988]

I am trying to obtain x,y coordinates by clicking on a graph in png format.
The following code works properly but it looks like that
x and y have a strange range, for instance y decreases its value the further you go up.
What exactly should I implement in the following code in order to pre-establish
the x and y range?
I have tried with numpy, but it does not work.

import cv2
import numpy as np

def click_event(event, x, y, flags, param):
    #x=np.linspace(0,10,1) when enabled they
    #y=np.linspace(0,5,1)  just print [0.] [0.] for every mouse click
    if event == cv2.EVENT_LBUTTONDOWN:
        print (x, y)

file_name= (r"\Users\Desktop\pic.png")

img = cv2.imread(file_name)
print(img.shape)
cv2.imshow('original', img)
cv2.setMouseCallback("original", click_event)
cv2.waitKey(0)
cv2.destroyAllWindows