def test_moments_central_coords():
image = cp.zeros((20, 20), dtype=cp.double)
image[13:17, 13:17] = 1
mu_image = moments_central(image, (14.5, 14.5))
coords = cp.asarray(
np.array(
[[r, c] for r in range(13, 17) for c in range(13, 17)],
dtype=cp.double,
)
)
mu_coords = moments_coords_central(coords, (14.5, 14.5))
assert_array_almost_equal(mu_coords, mu_image)
# ensure that center is being calculated normally
mu_coords_calc_centroid = moments_coords_central(coords)
assert_array_almost_equal(mu_coords_calc_centroid, mu_coords)
# shift image by dx=3 dy=3
image = cp.zeros((20, 20), dtype=cp.double)
image[16:20, 16:20] = 1
mu_image = moments_central(image, (14.5, 14.5))
coords = cp.asarray(
np.array(
[[r, c] for r in range(16, 20) for c in range(16, 20)],
dtype=cp.double,
)
)
mu_coords = moments_coords_central(coords, (14.5, 14.5))
assert_array_almost_equal(mu_coords, mu_image)
def test_moments_normalized():
image = cp.zeros((20, 20), dtype=cp.double)
image[13:17, 13:17] = 1
mu = moments_central(image, (14.5, 14.5))
nu = moments_normalized(mu)
# shift image by dx=-3, dy=-3 and scale by 0.5
image2 = cp.zeros((20, 20), dtype=cp.double)
image2[11:13, 11:13] = 1
mu2 = moments_central(image2, (11.5, 11.5))
nu2 = moments_normalized(mu2)
# central moments must be translation and scale invariant
assert_array_almost_equal(nu, nu2, decimal=1)
def test_moments_hu():
moments_hu = pytest.importorskip("skimage.measure.moments_hu")
image = cp.zeros((20, 20), dtype=cp.double)
image[13:15, 13:17] = 1
mu = moments_central(image, (13.5, 14.5))
nu = moments_normalized(mu)
hu = moments_hu(nu)
# shift image by dx=2, dy=3, scale by 0.5 and rotate by 90deg
image2 = cp.zeros((20, 20), dtype=cp.double)
image2[11, 11:13] = 1
image2 = image2.T
mu2 = moments_central(image2, (11.5, 11))
nu2 = moments_normalized(mu2)
hu2 = moments_hu(nu2)
# central moments must be translation and scale invariant
assert_array_almost_equal(hu, hu2, decimal=1)
def test_moments_normalized_3d():
image = cp.asarray(draw.ellipsoid(1, 1, 10))
mu_image = moments_central(image)
nu = moments_normalized(mu_image)
assert nu[0, 0, 2] > nu[0, 2, 0]
assert_almost_equal(nu[0, 2, 0], nu[2, 0, 0])
coords = cp.where(image)
mu_coords = moments_coords_central(coords)
assert_array_almost_equal(mu_coords, mu_image)
def test_moments_central():
image = cp.zeros((20, 20), dtype=cp.double)
image[14, 14] = 1
image[15, 15] = 1
image[14, 15] = 0.5
image[15, 14] = 0.5
mu = moments_central(image, (14.5, 14.5))
# check for proper centroid computation
mu_calc_centroid = moments_central(image)
assert_array_equal(mu, mu_calc_centroid)
# shift image by dx=2, dy=2
image2 = cp.zeros((20, 20), dtype=cp.double)
image2[16, 16] = 1
image2[17, 17] = 1
image2[16, 17] = 0.5
image2[17, 16] = 0.5
mu2 = moments_central(image2, (14.5 + 2, 14.5 + 2))
# central moments must be translation invariant
assert_array_equal(mu, mu2)