2.6.8.4. Image manipulation and NumPy arrays

This example shows how to do image manipulation using common NumPy arrays tricks.

import numpy as np
import scipy as sp
import matplotlib.pyplot as plt

face = sp.datasets.face(gray=True)
face[10:13, 20:23]
face[100:120] = 255

lx, ly = face.shape
X, Y = np.ogrid[0:lx, 0:ly]
mask = (X - lx / 2) ** 2 + (Y - ly / 2) ** 2 > lx * ly / 4
face[mask] = 0
face[range(400), range(400)] = 255

plt.figure(figsize=(3, 3))
plt.axes([0, 0, 1, 1])
plt.imshow(face, cmap=plt.cm.gray)
plt.axis("off")

plt.show()