新建文件_multiotsu.pyx
#cython: cdivision=True
#cython: boundscheck=False
#cython: nonecheck=False
#cython: wraparound=False
import numpy as np
cimport numpy as cnp
cimport cython
def _get_multiotsu_thresh_indices_lut(float [::1] prob,
Py_ssize_t thresh_count):
cdef Py_ssize_t nbins = prob.shape[0]
py_thresh_indices = np.empty(thresh_count, dtype=np.intp)
cdef Py_ssize_t[::1] thresh_indices = py_thresh_indices
cdef Py_ssize_t[::1] current_indices = np.empty(thresh_count, dtype=np.intp)
cdef float [::1] var_btwcls = np.zeros((nbins * (nbins + 1)) / 2,
dtype=np.float32)
cdef float [::1] zeroth_moment = np.empty(nbins, dtype=np.float32)
cdef float [::1] first_moment = np.empty(nbins, dtype=np.float32)
with nogil:
_set_var_btwcls_lut(prob, nbins, var_btwcls, zeroth_moment,
first_moment)
_set_thresh_indices_lut(var_btwcls, hist_idx=0,
thresh_idx=0, nbins=nbins,
thresh_count=thresh_count, sigma_max=0,
current_indices=current_indices,
thresh_indices=thresh_indices)
return py_thresh_indices
cdef void _set_var_btwcls_lut(float [::1] prob,
Py_ssize_t nbins,
float [::1] var_btwcls,
float [::1] zeroth_moment,
float [::1] first_moment) nogil:
cdef cnp.intp_t i, j, idx
cdef float zeroth_moment_ij, first_moment_ij
zeroth_moment[0] = prob[0]
first_moment[0] = prob[0]
for i in range(1, nbins):
zeroth_moment[i] = zeroth_moment[i - 1] + prob[i]
first_moment[i] = first_moment[i - 1] + i * prob[i]
if zeroth_moment[i] > 0:
var_btwcls[i] = (first_moment[i]**2) / zeroth_moment[i]
idx = nbins
for i in range(1, nbins):
for j in range(i, nbins):
zeroth_moment_ij = zeroth_moment[j] - zeroth_moment[i - 1]
if zeroth_moment_ij > 0:
first_moment_ij = first_moment[j] - first_moment[i - 1]
var_btwcls[idx] = (first_moment_ij**2) / zeroth_moment_ij
idx += 1
cdef float _get_var_btwclas_lut(float [::1] var_btwcls, Py_ssize_t i,
Py_ssize_t j, Py_ssize_t nbins) nogil:
cdef cnp.intp_t idx = (i * (2 * nbins - i + 1)) / 2 + j - i
return var_btwcls[idx]
cdef float _set_thresh_indices_lut(float[::1] var_btwcls, Py_ssize_t hist_idx,
Py_ssize_t thresh_idx, Py_ssize_t nbins,
Py_ssize_t thresh_count, float sigma_max,
Py_ssize_t[::1] current_indices,
Py_ssize_t[::1] thresh_indices) nogil:
cdef cnp.intp_t idx
cdef float sigma
if thresh_idx < thresh_count:
for idx in range(hist_idx, nbins - thresh_count + thresh_idx):
current_indices[thresh_idx] = idx
sigma_max = _set_thresh_indices_lut(var_btwcls, hist_idx=idx + 1,
thresh_idx=thresh_idx + 1,
nbins=nbins,
thresh_count=thresh_count,
sigma_max=sigma_max,
current_indices=current_indices,
thresh_indices=thresh_indices)
else:
sigma = (_get_var_btwclas_lut(var_btwcls, 0, current_indices[0], nbins)
+ _get_var_btwclas_lut(var_btwcls,
current_indices[thresh_count - 1] + 1,
nbins - 1, nbins))
for idx in range(thresh_count - 1):
sigma += _get_var_btwclas_lut(var_btwcls, current_indices[idx] + 1,
current_indices[idx + 1], nbins)
if sigma > sigma_max:
sigma_max = sigma
thresh_indices[:] = current_indices[:]
return sigma_max
def _get_multiotsu_thresh_indices(float [::1] prob, Py_ssize_t thresh_count):
cdef Py_ssize_t nbins = prob.shape[0]
py_thresh_indices = np.empty(thresh_count, dtype=np.intp)
cdef Py_ssize_t[::1] thresh_indices = py_thresh_indices
cdef Py_ssize_t[::1] current_indices = np.empty(thresh_count, dtype=np.intp)
cdef float [::1] zeroth_moment = np.empty(nbins, dtype=np.float32)
cdef float [::1] first_moment = np.empty(nbins, dtype=np.float32)
with nogil:
_set_moments_lut_first_row(prob, nbins, zeroth_moment, first_moment)
_set_thresh_indices(zeroth_moment, first_moment, hist_idx=0,
thresh_idx=0, nbins=nbins,
thresh_count=thresh_count, sigma_max=0,
current_indices=current_indices,
thresh_indices=thresh_indices)
return py_thresh_indices
cdef void _set_moments_lut_first_row(float [::1] prob,
Py_ssize_t nbins,
float [::1] zeroth_moment,
float [::1] first_moment) nogil:
cdef cnp.intp_t i
zeroth_moment[0] = prob[0]
first_moment[0] = prob[0]
for i in range(1, nbins):
zeroth_moment[i] = zeroth_moment[i - 1] + prob[i]
first_moment[i] = first_moment[i - 1] + i * prob[i]
cdef float _get_var_btwclas(float [::1] zeroth_moment,
float [::1] first_moment,
Py_ssize_t i, Py_ssize_t j) nogil:
cdef float zeroth_moment_ij, first_moment_ij
if i == 0:
if zeroth_moment[i] > 0:
return (first_moment[j]**2) / zeroth_moment[j]
else:
zeroth_moment_ij = zeroth_moment[j] - zeroth_moment[i - 1]
if zeroth_moment_ij > 0:
first_moment_ij = first_moment[j] - first_moment[i - 1]
return (first_moment_ij**2) / zeroth_moment_ij
return 0
cdef float _set_thresh_indices(float[::1] zeroth_moment,
float[::1] first_moment,
Py_ssize_t hist_idx,
Py_ssize_t thresh_idx, Py_ssize_t nbins,
Py_ssize_t thresh_count, float sigma_max,
Py_ssize_t[::1] current_indices,
Py_ssize_t[::1] thresh_indices) nogil:
cdef cnp.intp_t idx
cdef float sigma
if thresh_idx < thresh_count:
for idx in range(hist_idx, nbins - thresh_count + thresh_idx):
current_indices[thresh_idx] = idx
sigma_max = _set_thresh_indices(zeroth_moment,
first_moment,
hist_idx=idx + 1,
thresh_idx=thresh_idx + 1,
nbins=nbins,
thresh_count=thresh_count,
sigma_max=sigma_max,
current_indices=current_indices,
thresh_indices=thresh_indices)
else:
sigma = (_get_var_btwclas(zeroth_moment, first_moment, 0,
current_indices[0])
+ _get_var_btwclas(zeroth_moment, first_moment,
current_indices[thresh_count - 1] + 1,
nbins - 1))
for idx in range(thresh_count - 1):
sigma += _get_var_btwclas(zeroth_moment, first_moment,
current_indices[idx] + 1,
current_indices[idx + 1])
if sigma > sigma_max:
sigma_max = sigma
thresh_indices[:] = current_indices[:]
return sigma_max
在同一文件夹下新建setup.py
from distutils.core import setup
from distutils.extension import Extension
from Cython.Build import cythonize
from Cython.Distutils import build_ext
import numpy as np
# ext_module = cythonize("TestOMP.pyx")
ext_module = Extension(
"_multiotsu",
["_multiotsu.pyx"],
)
setup(
cmdclass={'build_ext': build_ext},
ext_modules=[ext_module],
include_dirs=[np.get_include()]
)
cmd到setup.py文件夹下，然后使用命令
python setup.py build_ext --inplace
将_multiotsu.cp35-win_amd64.pyd复制到与_multiotsu.pyx同一文件夹下，然后重命名为_multiotsu.pyd。
具体如何使用请参考：https://blog.csdn.net/u013066730/article/details/103462952
来源：CSDN
作者：mjiansun
链接：https://blog.csdn.net/u013066730/article/details/103462829