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scikit-image/scikits/image/morphology/tests/test_skeletonize.py
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2011-10-17 08:32:19 +01:00

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Python

import numpy as np
from scikits.image.morphology import skeletonize
import numpy.testing
from scikits.image.draw import draw
from scipy.ndimage import correlate
from scikits.image.io import imread
from scikits.image import data_dir
import os.path
class TestSkeletonize():
def test_skeletonize_no_foreground(self):
im = np.zeros((5,5))
result = skeletonize(im)
numpy.testing.assert_array_equal(result, np.zeros((5,5)))
def test_skeletonize_wrong_dim1(self):
im = np.zeros((5))
numpy.testing.assert_raises(ValueError, skeletonize, im)
def test_skeletonize_wrong_dim2(self):
im = np.zeros((5, 5, 5))
numpy.testing.assert_raises(ValueError, skeletonize, im)
def test_skeletonize_not_binary(self):
im = np.zeros((5, 5))
im[0, 0] = 1
im[0, 1] = 2
numpy.testing.assert_raises(ValueError, skeletonize, im)
def test_skeletonize_unexpected_value(self):
im = np.zeros((5, 5))
im[0, 0] = 2
numpy.testing.assert_raises(ValueError, skeletonize, im)
def test_skeletonize_all_foreground(self):
im = np.ones((3,4))
result = skeletonize(im)
def test_skeletonize_single_point(self):
im = np.zeros((5, 5), np.uint8)
im[3, 3] = 1
result = skeletonize(im)
numpy.testing.assert_array_equal(result, im)
def test_skeletonize_already_thinned(self):
im = np.zeros((5, 5), np.uint8)
im[3,1:-1] = 1
im[2, -1] = 1
im[4, 0] = 1
result = skeletonize(im)
numpy.testing.assert_array_equal(result, im)
def test_skeletonize_output(self):
im = imread(os.path.join(data_dir, "bw_text.png"), as_grey=True)
# make black the foreground
im = (im==0)
result = skeletonize(im)
expected = np.load(os.path.join(data_dir, "bw_text_skeleton.npy"))
numpy.testing.assert_array_equal(result, expected)
def test_skeletonize_num_neighbours(self):
# an empty image
image = np.zeros((300, 300))
# foreground object 1
image[10:-10, 10:100] = 1
image[-100:-10, 10:-10] = 1
image[10:-10, -100:-10] = 1
# foreground object 2
rs, cs = draw.bresenham(250, 150, 10, 280)
for i in range(10): image[rs+i, cs] = 1
rs, cs = draw.bresenham(10, 150, 250, 280)
for i in range(20): image[rs+i, cs] = 1
# foreground object 3
ir, ic = np.indices(image.shape)
circle1 = (ic - 135)**2 + (ir - 150)**2 < 30**2
circle2 = (ic - 135)**2 + (ir - 150)**2 < 20**2
image[circle1] = 1
image[circle2] = 0
result = skeletonize(image)
# there should never be a 2x2 block of foreground pixels in a skeleton
mask = np.array([[1, 1],
[1, 1]], np.uint8)
blocks = correlate(result, mask, mode='constant')
assert not numpy.any(blocks == 4)
if __name__ == '__main__':
np.testing.run_module_suite()