2.6.8.3. Plot the block mean of an image

An example showing how to use broad-casting to plot the mean of blocks of an image.

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

f = sp.datasets.face(gray=True)
sx, sy = f.shape
X, Y = np.ogrid[0:sx, 0:sy]

regions = sy // 6 * (X // 4) + Y // 6
block_mean = sp.ndimage.mean(f, labels=regions, index=np.arange(1, regions.max() + 1))
block_mean.shape = (sx // 4, sy // 6)

plt.figure(figsize=(5, 5))
plt.imshow(block_mean, cmap=plt.cm.gray)
plt.axis("off")

plt.show()