Конвертация цветного изображения в черно-белое

#!/usr/bin/env python3
import numpy as np
from PIL import Image
 
img = Image.open('image.jpg')
arr = np.asarray(img, dtype='uint8')
 
k = np.array([[[0.2989, 0.587, 0.114]]])
sums = np.round(np.sum(arr*k, axis=2)).astype(np.uint8)
arr2 = np.repeat(sums, 3).reshape(arr.shape)
 
img2 = Image.fromarray(arr2)
img2.save('result_bw.png')

#!/usr/bin/env python3
import numpy as np
from PIL import Image
 
img = Image.open('image.jpg')
arr = np.asarray(img, dtype='uint8')
x, y, _ = arr.shape
 
k = np.array([[[0.2989, 0.587, 0.114]]])
arr2 = np.round(np.sum(arr*k, axis=2)).astype(np.uint8).reshape((x, y))
 
img2 = Image.fromarray(arr2)
img2.save('result_bw.png')

import numpy as np
from PIL import Image
 
img = Image.open('image.jpg')
arr = np.asarray(img, dtype='uint8')
k = np.array([0.2989, 0.587, 0.114])
w, h, _ = arr.shape
arr.reshape(w*h,3)
out=np.matmul(arr, k)
out.reshape(w,h)
img2 = Image.fromarray(out.astype(np.uint8))
img2.save('result_bw.png')

import numpy as np
from PIL import Image
 
img = Image.open('image.jpg')
arr = np.asarray(img, dtype='uint8')
x, y, _ = arr.shape
 
k = np.array([[[0.2989, 0.587, 0.114]]])
arr2 = np.round(np.sum(arr*k, axis=2)).astype(np.uint8).reshape((x, y))
 
img2 = Image.fromarray(arr2)
img2.save('result_bw.png')

from PIL import Image
import numpy as np
 
 
def bw_convert():
    img = Image.open('image.jpg')
    image = np.asarray(img)
    # узнаем размерность массива
    x, y, _ = image.shape
    k = np.array([0.2989, 0.587, 0.114])
    arr = np.round(np.sum(image * k, axis=2)).astype(np.uint8).reshape((x, y))
    image2 = Image.fromarray(arr)
    image2.save('res.jpg')

import numpy as np
from PIL import Image
 
 
def bw_convert():
    img = Image.open('image.jpg')
    arr = np.asarray(img, dtype='uint8')
    x, y, _ = arr.shape
 
    k = np.array([[[0.2989, 0.587, 0.114]]])
    arr2 = np.round(np.sum(arr * k, axis=2)).astype(np.uint8).reshape((x, y))
 
    img2 = Image.fromarray(arr2)
    img2.save('res.jpg')