mirror of
https://github.com/wassname/scikit-image.git
synced 2026-07-13 17:45:20 +08:00
Johannes Schönberger
53 lines
1.7 KiB
Cython
53 lines
1.7 KiB
Cython
#cython: boundscheck=False
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#cython: wraparound=False
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#cython: cdivision=True
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import numpy as np
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cimport numpy as np
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def central_moments(np.ndarray[np.double_t, ndim=2] array, double cr, double cc,
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int order):
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cdef int p, q, r, c
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cdef np.ndarray[np.double_t, ndim=2] mu
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mu = np.zeros((order + 1, order + 1), 'double')
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for p in range(order + 1):
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for q in range(order + 1):
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for r in range(array.shape[0]):
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for c in range(array.shape[1]):
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mu[p,q] += array[r,c] * (r - cr) ** q * (c - cc) ** p
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return mu
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def normalized_moments(np.ndarray[np.double_t, ndim=2] mu, int order):
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cdef int p, q
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cdef np.ndarray[np.double_t, ndim=2] nu
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nu = np.zeros((order + 1, order + 1), 'double')
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for p in range(order + 1):
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for q in range(order + 1):
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if p + q >= 2:
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nu[p,q] = mu[p,q] / mu[0,0]**(<double>(p + q) / 2 + 1)
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else:
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nu[p,q] = np.nan
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return nu
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def hu_moments(np.ndarray[np.double_t, ndim=2] nu):
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cdef np.ndarray[np.double_t, ndim=1] hu = np.zeros((7,), 'double')
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cdef double t0 = nu[3,0] + nu[1,2]
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cdef double t1 = nu[2,1] + nu[0,3]
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cdef double q0 = t0 * t0
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cdef double q1 = t1 * t1
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cdef double n4 = 4 * nu[1,1]
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cdef double s = nu[2,0] + nu[0,2]
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cdef double d = nu[2,0] - nu[0,2]
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hu[0] = s
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hu[1] = d * d + n4 * nu[1,1]
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hu[3] = q0 + q1
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hu[5] = d * (q0 - q1) + n4 * t0 * t1
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t0 *= q0 - 3 * q1
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t1 *= 3 * q0 - q1
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q0 = nu[3,0]- 3 * nu[1,2]
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q1 = 3 * nu[2,1] - nu[0,3]
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hu[2] = q0 * q0 + q1 * q1
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hu[4] = q0 * t0 + q1 * t1
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hu[6] = q1 * t0 - q0 * t1
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return hu
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