2.6.8.14. Measurements from images

This examples shows how to measure quantities from various images.

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

rng = np.random.default_rng(27446968)
n = 10
l = 256
im = np.zeros((l, l))
points = l * rng.random((2, n**2))
im[(points[0]).astype(int), (points[1]).astype(int)] = 1
im = sp.ndimage.gaussian_filter(im, sigma=l / (4.0 * n))

mask = im > im.mean()

label_im, nb_labels = sp.ndimage.label(mask)

sizes = sp.ndimage.sum(mask, label_im, range(nb_labels + 1))
mask_size = sizes < 1000
remove_pixel = mask_size[label_im]
label_im[remove_pixel] = 0
labels = np.unique(label_im)
label_clean = np.searchsorted(labels, label_im)


plt.figure(figsize=(6, 3))

plt.subplot(121)
plt.imshow(label_im, cmap="nipy_spectral")
plt.axis("off")
plt.subplot(122)
plt.imshow(label_clean, vmax=nb_labels, cmap="nipy_spectral")
plt.axis("off")

plt.subplots_adjust(wspace=0.01, hspace=0.01, top=1, bottom=0, left=0, right=1)
plt.show()