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Alexandre Fioravante de Siqueira
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Solving white space + Correcting code Solving white spaces Solving white spaces Solving white spaces Answering comments Correcting silly mistakes Solving white spaces Trying again... now with Travis enabled
60 lines
1.6 KiB
Python
60 lines
1.6 KiB
Python
"""
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====================
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Local Otsu Threshold
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====================
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This example shows how Otsu's threshold [1]_ method can be applied locally. For
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each pixel, an "optimal" threshold is determined by maximizing the variance
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between two classes of pixels of the local neighborhood defined by a
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structuring element.
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The example compares the local threshold with the global threshold.
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.. Note: local is much slower than global thresholding
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.. [1] http://en.wikipedia.org/wiki/Otsu's_method
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"""
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from skimage import data
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from skimage.morphology import disk
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from skimage.filters import threshold_otsu, rank
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from skimage.util import img_as_ubyte
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import matplotlib
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import matplotlib.pyplot as plt
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matplotlib.rcParams['font.size'] = 9
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img = img_as_ubyte(data.page())
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radius = 15
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selem = disk(radius)
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local_otsu = rank.otsu(img, selem)
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threshold_global_otsu = threshold_otsu(img)
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global_otsu = img >= threshold_global_otsu
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fig, ax = plt.subplots(2, 2, figsize=(8, 5), sharex=True, sharey=True,
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subplot_kw={'adjustable': 'box-forced'})
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ax0, ax1, ax2, ax3 = ax.ravel()
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fig.colorbar(ax0.imshow(img, cmap=plt.cm.gray),
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ax=ax0, orientation='horizontal')
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ax0.set_title('Original')
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ax0.axis('off')
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fig.colorbar(ax1.imshow(local_otsu, cmap=plt.cm.gray),
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ax=ax1, orientation='horizontal')
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ax1.set_title('Local Otsu (radius=%d)' % radius)
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ax1.axis('off')
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ax2.imshow(img >= local_otsu, cmap=plt.cm.gray)
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ax2.set_title('Original >= Local Otsu' % threshold_global_otsu)
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ax2.axis('off')
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ax3.imshow(global_otsu, cmap=plt.cm.gray)
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ax3.set_title('Global Otsu (threshold = %d)' % threshold_global_otsu)
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ax3.axis('off')
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plt.show()
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