寻找局部最大值

这个 peak_local_max 函数返回图像中局部峰值(最大值)的坐标。在内部，使用最大值滤波来寻找局部最大值。此操作将扩展原始图像，并合并比扩展大小更接近的相邻局部最大值。将原始图像与放大图像相等的位置作为局部最大值返回。

from scipy import ndimage as ndi
import matplotlib.pyplot as plt
from skimage.feature import peak_local_max
from skimage import data, img_as_float

im = img_as_float(data.coins())

# image_max is the dilation of im with a 20*20 structuring element
# It is used within peak_local_max function
image_max = ndi.maximum_filter(im, size=20, mode='constant')

# Comparison between image_max and im to find the coordinates of local maxima
coordinates = peak_local_max(im, min_distance=20)

# display results
fig, axes = plt.subplots(1, 3, figsize=(8, 3), sharex=True, sharey=True)
ax = axes.ravel()
ax[0].imshow(im, cmap=plt.cm.gray)
ax[0].axis('off')
ax[0].set_title('Original')

ax[1].imshow(image_max, cmap=plt.cm.gray)
ax[1].axis('off')
ax[1].set_title('Maximum filter')

ax[2].imshow(im, cmap=plt.cm.gray)
ax[2].autoscale(False)
ax[2].plot(coordinates[:, 1], coordinates[:, 0], 'r.')
ax[2].axis('off')
ax[2].set_title('Peak local max')

fig.tight_layout()

plt.show()