mirror of
https://github.com/wassname/scikit-image.git
synced 2026-06-28 01:46:21 +08:00
Siva Prasad Varma
45 lines
1016 B
Python
45 lines
1016 B
Python
"""
|
|
============
|
|
Thresholding
|
|
============
|
|
|
|
Thresholding is used to create a binary image. This example uses Otsu's method
|
|
to calculate the threshold value.
|
|
|
|
Otsu's method calculates an "optimal" threshold (marked by a red line in the
|
|
histogram below) by maximizing the variance between two classes of pixels,
|
|
which are separated by the threshold. Equivalently, this threshold minimizes
|
|
the intra-class variance.
|
|
|
|
.. [1] http://en.wikipedia.org/wiki/Otsu's_method
|
|
|
|
"""
|
|
import matplotlib
|
|
import matplotlib.pyplot as plt
|
|
|
|
from skimage.data import camera
|
|
from skimage.filter import threshold_otsu
|
|
|
|
|
|
matplotlib.rcParams['font.size'] = 9
|
|
|
|
|
|
image = camera()
|
|
thresh = threshold_otsu(image)
|
|
binary = image > thresh
|
|
|
|
fig, (ax1, ax2, ax3) = plt.subplots(1, 3, figsize=(8, 2.5))
|
|
ax1.imshow(image, cmap=plt.cm.gray)
|
|
ax1.set_title('Original')
|
|
ax1.axis('off')
|
|
|
|
ax2.hist(image)
|
|
ax2.set_title('Histogram')
|
|
ax2.axvline(thresh, color='r')
|
|
|
|
ax3.imshow(binary, cmap=plt.cm.gray)
|
|
ax3.set_title('Thresholded')
|
|
ax3.axis('off')
|
|
|
|
plt.show()
|