mirror of
https://github.com/wassname/scikit-image.git
synced 2026-06-28 03:03:07 +08:00
Tony S Yu
51 lines
1.5 KiB
Python
51 lines
1.5 KiB
Python
"""
|
|
===============================================================================
|
|
Finding local maxima
|
|
===============================================================================
|
|
|
|
The ``peak_local_max`` function returns the coordinates of local peaks (maxima)
|
|
in an image. A maximum filter is used for finding local maxima. This operation
|
|
dilates the original image and merges neighboring local maxima closer than the
|
|
size of the dilation. Locations where the original image is equal to the
|
|
dilated image are returned as local maxima.
|
|
|
|
"""
|
|
from scipy import ndimage
|
|
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 = ndimage.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
|
|
plt.figure(figsize=(8, 3))
|
|
plt.subplot(131)
|
|
plt.imshow(im, cmap=plt.cm.gray)
|
|
plt.axis('off')
|
|
plt.title('Original')
|
|
|
|
plt.subplot(132)
|
|
plt.imshow(image_max, cmap=plt.cm.gray)
|
|
plt.axis('off')
|
|
plt.title('Maximum filter')
|
|
|
|
plt.subplot(133)
|
|
plt.imshow(im, cmap=plt.cm.gray)
|
|
plt.autoscale(False)
|
|
plt.plot([p[1] for p in coordinates], [p[0] for p in coordinates], 'r.')
|
|
plt.axis('off')
|
|
plt.title('Peak local max')
|
|
|
|
plt.subplots_adjust(wspace=0.02, hspace=0.02, top=0.9,
|
|
bottom=0.02, left=0.02, right=0.98)
|
|
|
|
plt.show()
|
|
|