mirror of
https://github.com/wassname/scikit-image.git
synced 2026-06-29 16:00:12 +08:00
Johannes Schönberger
73 lines
2.2 KiB
Python
73 lines
2.2 KiB
Python
from numpy.testing import assert_equal, assert_almost_equal
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import numpy as np
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from skimage.measure import (moments, moments_central, moments_normalized,
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moments_hu)
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def test_moments():
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image = np.zeros((20, 20), dtype=np.double)
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image[14, 14] = 1
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image[15, 15] = 1
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image[14, 15] = 0.5
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image[15, 14] = 0.5
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m = moments(image)
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assert_equal(m[0, 0], 3)
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assert_almost_equal(m[0, 1] / m[0, 0], 14.5)
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assert_almost_equal(m[1, 0] / m[0, 0], 14.5)
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def test_moments_central():
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image = np.zeros((20, 20), dtype=np.double)
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image[14, 14] = 1
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image[15, 15] = 1
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image[14, 15] = 0.5
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image[15, 14] = 0.5
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mu = moments_central(image, 14.5, 14.5)
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# shift image by dx=2, dy=2
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image2 = np.zeros((20, 20), dtype=np.double)
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image2[16, 16] = 1
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image2[17, 17] = 1
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image2[16, 17] = 0.5
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image2[17, 16] = 0.5
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mu2 = moments_central(image2, 14.5 + 2, 14.5 + 2)
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# central moments must be translation invariant
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assert_equal(mu, mu2)
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def test_moments_normalized():
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image = np.zeros((20, 20), dtype=np.double)
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image[13:17, 13:17] = 1
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mu = moments_central(image, 14.5, 14.5)
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nu = moments_normalized(mu)
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# shift image by dx=-3, dy=-3 and scale by 0.5
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image2 = np.zeros((20, 20), dtype=np.double)
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image2[11:13, 11:13] = 1
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mu2 = moments_central(image2, 11.5, 11.5)
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nu2 = moments_normalized(mu2)
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# central moments must be translation and scale invariant
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assert_almost_equal(nu, nu2, decimal=1)
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def test_moments_hu():
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image = np.zeros((20, 20), dtype=np.double)
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image[13:15, 13:17] = 1
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mu = moments_central(image, 13.5, 14.5)
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nu = moments_normalized(mu)
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hu = moments_hu(nu)
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# shift image by dx=2, dy=3, scale by 0.5 and rotate by 90deg
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image2 = np.zeros((20, 20), dtype=np.double)
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image2[11, 11:13] = 1
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image2 = image2.T
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mu2 = moments_central(image2, 11.5, 11)
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nu2 = moments_normalized(mu2)
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hu2 = moments_hu(nu2)
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# central moments must be translation and scale invariant
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assert_almost_equal(hu, hu2, decimal=1)
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if __name__ == "__main__":
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from numpy.testing import run_module_suite
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run_module_suite()
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