image_compression.py

import numpy as np
import matplotlib.pyplot as plt
from PIL import Image

fname = 'daniel-plan-u1WcrpHk6Pg-unsplash.jpg'
image = Image.open(fname).convert("L")
img_mat = np.asarray(image)
plt.imshow(img_mat, cmap='gray', vmin=0, vmax=255)
plt.show()

U, s, V = np.linalg.svd(img_mat, full_matrices=False)
s = np.diag(s)

for k in range(50):
  approx=U[:, :k] @ s[0:k, :k] @ V[:k, :]
  img = plt.imshow(approx, cmap='gray')
  plt.title(f'SVD approximation with degree of {str(k)}')
  plt.plot()
  plt.draw()
  plt.pause(0.0001)
  plt.clf()

approx=U[:, :50] @ s[0:50, :50] @ V[:50, :]
img = plt.imshow(approx, cmap='gray')
plt.title(f'SVD approximation with degree of {str(50)}')
plt.plot()
plt.pause(5)