img = rgb2gray(imread('image.png')); 

import matplotlib.image as mpimg
img = mpimg.imread('image.png') 

lum_img = img[:,:,0] 

import numpy as np
 
def rgb2gray(rgb):
 
 r, g, b = rgb[:,:,0], rgb[:,:,1], rgb[:,:,2]
 gray = 0.2989 * r + 0.5870 * g + 0.1140 * b
 
 return gray

from PIL import Image
img = Image.open('image.png').convert('LA')
img.save('greyscale.png') 

Y' = 0.299 R + 0.587 G + 0.114 B 

import numpy as np
import matplotlib.pyplot as plt
import matplotlib.image as mpimg
 
def rgb2gray(rgb):
 return np.dot(rgb[...,:3], [0.299, 0.587, 0.114])
 
img = mpimg.imread('image.png') 
gray = rgb2gray(img) 
plt.imshow(gray, cmap = plt.get_cmap('gray'))
plt.show()