cv.py

import cv2
  
# Import the image
file_name = "gfg_black.png"
  
# Read the image
src = cv2.imread(file_name, 1)
  
# Convert image to image gray
tmp = cv2.cvtColor(src, cv2.COLOR_BGR2GRAY)
  
# Applying thresholding technique
_, alpha = cv2.threshold(tmp, 0, 255, cv2.THRESH_BINARY)
  
# Using cv2.split() to split channels 
# of coloured image
b, g, r = cv2.split(src)
  
# Making list of Red, Green, Blue
# Channels and alpha
rgba = [b, g, r, alpha]
  
# Using cv2.merge() to merge rgba
# into a coloured/multi-channeled image
dst = cv2.merge(rgba, 4)
  
# Writing and saving to a new image
cv2.imwrite("gfg_white.png", dst)