凸包

二值图像的凸包是指包含输入中所有白色像素的最小凸多边形中包含的像素集。

算法的良好概述在 Steve Eddin 的博客 中给出。

import matplotlib.pyplot as plt

from skimage.morphology import convex_hull_image
from skimage import data, img_as_float
from skimage.util import invert

# The original image is inverted as the object must be white.
image = invert(data.horse())

chull = convex_hull_image(image)

fig, axes = plt.subplots(1, 2, figsize=(8, 4))
ax = axes.ravel()

ax[0].set_title('Original picture')
ax[0].imshow(image, cmap=plt.cm.gray)
ax[0].set_axis_off()

ax[1].set_title('Transformed picture')
ax[1].imshow(chull, cmap=plt.cm.gray)
ax[1].set_axis_off()

plt.tight_layout()
plt.show()

我们准备第二个绘图以显示差异。

chull_diff = img_as_float(chull.copy())
chull_diff[image] = 2

fig, ax = plt.subplots()
ax.imshow(chull_diff, cmap=plt.cm.gray)
ax.set_title('Difference')
plt.show()