In [32]: 
import numpy as np
import matplotlib.pyplot as pt
In [33]: 
from PIL import Image

with Image.open("andreas.jpeg").resize((500,500)) as img:
    rgb_img = np.array(img)
rgb_img.shape
Out[33]:
(500, 500, 3)
In [34]: 
img = np.sum(rgb_img, axis=-1)
In [35]: 
pt.imshow(img, cmap="gray")
Out[35]:
<matplotlib.image.AxesImage at 0x7f17031adcc0>
In [36]: 
u, sigma, vt = np.linalg.svd(img)
sigma

pt.plot(sigma)
Out[36]:
[<matplotlib.lines.Line2D at 0x7f1703182da0>]
In [45]: 
compressed_img = (
    sigma[0] * np.outer(u[:, 0], vt[0])
    )

pt.imshow(compressed_img, cmap="gray")
Out[45]:
<matplotlib.image.AxesImage at 0x7f1701e73e80>
In [37]: