python update memory snippet

gistfile1.txt

import myLib 
import cv2 
import numpy as np imgPtr = myLib.GetImgBuffer(img1, cols1, rows1) 
numpy_array = np.frombuffer(imgPtr, dtype=np.uint8) 
numpy_array.shape = (rows1, cols1)
//assume: rows1 = cols1 = 1024
//change the image in python
dst = np.ones((1024,1024), dtype=np.uint8)

//update data in the buffer
np.copyto(numpy_array, dst) //IS THIS CORRECT FOR UPDATING THE MEMORY IN THE BUFFER??
numpy_array.shape = dst.shape

 //create another numpy array from the updated buffer
numpy_array2 = np.frombuffer(imgPtr, dtype=np.uint8)
numpy_array2.shape = numpy_array.shape // this array display the correct change but when we pick up 
//the change in c++, only ~ quarter of the image is changed)
cv2.imshow('img - retrieve image from updated buffer & display in Python', numpy_array2)
cv2.waitKey(0)