mirror of
https://github.com/wassname/scikit-image.git
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emmanuelle
55f5103dd8
Modified travis_script.sh to account for the new structure of the gallery Added README.txt files in directories of gallery examples Fixed references to gallery images in user guide pages Fixed broken links
48 lines
1.5 KiB
Python
48 lines
1.5 KiB
Python
"""
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====================
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Finding local maxima
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====================
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The ``peak_local_max`` function returns the coordinates of local peaks (maxima)
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in an image. A maximum filter is used for finding local maxima. This operation
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dilates the original image and merges neighboring local maxima closer than the
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size of the dilation. Locations where the original image is equal to the
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dilated image are returned as local maxima.
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"""
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from scipy import ndimage as ndi
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import matplotlib.pyplot as plt
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from skimage.feature import peak_local_max
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from skimage import data, img_as_float
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im = img_as_float(data.coins())
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# image_max is the dilation of im with a 20*20 structuring element
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# It is used within peak_local_max function
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image_max = ndi.maximum_filter(im, size=20, mode='constant')
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# Comparison between image_max and im to find the coordinates of local maxima
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coordinates = peak_local_max(im, min_distance=20)
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# display results
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fig, ax = plt.subplots(1, 3, figsize=(8, 3), sharex=True, sharey=True, subplot_kw={'adjustable':'box-forced'})
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ax1, ax2, ax3 = ax.ravel()
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ax1.imshow(im, cmap=plt.cm.gray)
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ax1.axis('off')
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ax1.set_title('Original')
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ax2.imshow(image_max, cmap=plt.cm.gray)
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ax2.axis('off')
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ax2.set_title('Maximum filter')
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ax3.imshow(im, cmap=plt.cm.gray)
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ax3.autoscale(False)
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ax3.plot(coordinates[:, 1], coordinates[:, 0], 'r.')
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ax3.axis('off')
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ax3.set_title('Peak local max')
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fig.subplots_adjust(wspace=0.02, hspace=0.02, top=0.9,
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bottom=0.02, left=0.02, right=0.98)
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plt.show()
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