import cv2
import numpy as np 

img1 = cv2.imread('3D-Matplotlib.png')
img2 = cv2.imread('mainlogo.png')

rows, cols, channels = img2.shape
roi = img1[0:rows, 0:cols]

img2gray = cv2.cvtColor(img2, cv2.COLOR_BGR2GRAY)

ret,mask = cv2.threshold(img2gray, 220,255,cv2.THRESH_BINARY_INV)

mask_inv =cv2.bitwise_not(mask)

img1_bg = cv2.bitwise_and(roi,roi,mask = mask_inv)
img2_fg = cv2.bitwise_and(img2,img2, mask = mask)

dst = cv2.add(img1_bg,img2_fg)
img1[0:rows, 0:cols] = dst





cv2.imshow('add',dst)
cv2.waitKey()
cv2.destroyAllWindows()