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_morphology.py
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_morphology.py
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# Copyright (C) 2003-2005 Peter J. Verveer
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions
# are met:
#
# 1. Redistributions of source code must retain the above copyright
# notice, this list of conditions and the following disclaimer.
#
# 2. Redistributions in binary form must reproduce the above
# copyright notice, this list of conditions and the following
# disclaimer in the documentation and/or other materials provided
# with the distribution.
#
# 3. The name of the author may not be used to endorse or promote
# products derived from this software without specific prior
# written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS
# OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
# WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
# ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
# DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
# GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
# INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
# WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
# NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
# SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
import warnings
import operator
import numpy
from . import _ni_support
from . import _nd_image
from . import _filters
__all__ = ['iterate_structure', 'generate_binary_structure', 'binary_erosion',
'binary_dilation', 'binary_opening', 'binary_closing',
'binary_hit_or_miss', 'binary_propagation', 'binary_fill_holes',
'grey_erosion', 'grey_dilation', 'grey_opening', 'grey_closing',
'morphological_gradient', 'morphological_laplace', 'white_tophat',
'black_tophat', 'distance_transform_bf', 'distance_transform_cdt',
'distance_transform_edt']
def _center_is_true(structure, origin):
structure = numpy.array(structure)
coor = tuple([oo + ss // 2 for ss, oo in zip(structure.shape,
origin)])
return bool(structure[coor])
def iterate_structure(structure, iterations, origin=None):
"""
Iterate a structure by dilating it with itself.
Parameters
----------
structure : array_like
Structuring element (an array of bools, for example), to be dilated with
itself.
iterations : int
number of dilations performed on the structure with itself
origin : optional
If origin is None, only the iterated structure is returned. If
not, a tuple of the iterated structure and the modified origin is
returned.
Returns
-------
iterate_structure : ndarray of bools
A new structuring element obtained by dilating `structure`
(`iterations` - 1) times with itself.
See also
--------
generate_binary_structure
Examples
--------
>>> from scipy import ndimage
>>> struct = ndimage.generate_binary_structure(2, 1)
>>> struct.astype(int)
array([[0, 1, 0],
[1, 1, 1],
[0, 1, 0]])
>>> ndimage.iterate_structure(struct, 2).astype(int)
array([[0, 0, 1, 0, 0],
[0, 1, 1, 1, 0],
[1, 1, 1, 1, 1],
[0, 1, 1, 1, 0],
[0, 0, 1, 0, 0]])
>>> ndimage.iterate_structure(struct, 3).astype(int)
array([[0, 0, 0, 1, 0, 0, 0],
[0, 0, 1, 1, 1, 0, 0],
[0, 1, 1, 1, 1, 1, 0],
[1, 1, 1, 1, 1, 1, 1],
[0, 1, 1, 1, 1, 1, 0],
[0, 0, 1, 1, 1, 0, 0],
[0, 0, 0, 1, 0, 0, 0]])
"""
structure = numpy.asarray(structure)
if iterations < 2:
return structure.copy()
ni = iterations - 1
shape = [ii + ni * (ii - 1) for ii in structure.shape]
pos = [ni * (structure.shape[ii] // 2) for ii in range(len(shape))]
slc = tuple(slice(pos[ii], pos[ii] + structure.shape[ii], None)
for ii in range(len(shape)))
out = numpy.zeros(shape, bool)
out[slc] = structure != 0
out = binary_dilation(out, structure, iterations=ni)
if origin is None:
return out
else:
origin = _ni_support._normalize_sequence(origin, structure.ndim)
origin = [iterations * o for o in origin]
return out, origin
def generate_binary_structure(rank, connectivity):
"""
Generate a binary structure for binary morphological operations.
Parameters
----------
rank : int
Number of dimensions of the array to which the structuring element
will be applied, as returned by `np.ndim`.
connectivity : int
`connectivity` determines which elements of the output array belong
to the structure, i.e., are considered as neighbors of the central
element. Elements up to a squared distance of `connectivity` from
the center are considered neighbors. `connectivity` may range from 1
(no diagonal elements are neighbors) to `rank` (all elements are
neighbors).
Returns
-------
output : ndarray of bools
Structuring element which may be used for binary morphological
operations, with `rank` dimensions and all dimensions equal to 3.
See also
--------
iterate_structure, binary_dilation, binary_erosion
Notes
-----
`generate_binary_structure` can only create structuring elements with
dimensions equal to 3, i.e., minimal dimensions. For larger structuring
elements, that are useful e.g., for eroding large objects, one may either
use `iterate_structure`, or create directly custom arrays with
numpy functions such as `numpy.ones`.
Examples
--------
>>> from scipy import ndimage
>>> import numpy as np
>>> struct = ndimage.generate_binary_structure(2, 1)
>>> struct
array([[False, True, False],
[ True, True, True],
[False, True, False]], dtype=bool)
>>> a = np.zeros((5,5))
>>> a[2, 2] = 1
>>> a
array([[ 0., 0., 0., 0., 0.],
[ 0., 0., 0., 0., 0.],
[ 0., 0., 1., 0., 0.],
[ 0., 0., 0., 0., 0.],
[ 0., 0., 0., 0., 0.]])
>>> b = ndimage.binary_dilation(a, structure=struct).astype(a.dtype)
>>> b
array([[ 0., 0., 0., 0., 0.],
[ 0., 0., 1., 0., 0.],
[ 0., 1., 1., 1., 0.],
[ 0., 0., 1., 0., 0.],
[ 0., 0., 0., 0., 0.]])
>>> ndimage.binary_dilation(b, structure=struct).astype(a.dtype)
array([[ 0., 0., 1., 0., 0.],
[ 0., 1., 1., 1., 0.],
[ 1., 1., 1., 1., 1.],
[ 0., 1., 1., 1., 0.],
[ 0., 0., 1., 0., 0.]])
>>> struct = ndimage.generate_binary_structure(2, 2)
>>> struct
array([[ True, True, True],
[ True, True, True],
[ True, True, True]], dtype=bool)
>>> struct = ndimage.generate_binary_structure(3, 1)
>>> struct # no diagonal elements
array([[[False, False, False],
[False, True, False],
[False, False, False]],
[[False, True, False],
[ True, True, True],
[False, True, False]],
[[False, False, False],
[False, True, False],
[False, False, False]]], dtype=bool)
"""
if connectivity < 1:
connectivity = 1
if rank < 1:
return numpy.array(True, dtype=bool)
output = numpy.fabs(numpy.indices([3] * rank) - 1)
output = numpy.add.reduce(output, 0)
return output <= connectivity
def _binary_erosion(input, structure, iterations, mask, output,
border_value, origin, invert, brute_force):
try:
iterations = operator.index(iterations)
except TypeError as e:
raise TypeError('iterations parameter should be an integer') from e
input = numpy.asarray(input)
if numpy.iscomplexobj(input):
raise TypeError('Complex type not supported')
if structure is None:
structure = generate_binary_structure(input.ndim, 1)
else:
structure = numpy.asarray(structure, dtype=bool)
if structure.ndim != input.ndim:
raise RuntimeError('structure and input must have same dimensionality')
if not structure.flags.contiguous:
structure = structure.copy()
if numpy.prod(structure.shape, axis=0) < 1:
raise RuntimeError('structure must not be empty')
if mask is not None:
mask = numpy.asarray(mask)
if mask.shape != input.shape:
raise RuntimeError('mask and input must have equal sizes')
origin = _ni_support._normalize_sequence(origin, input.ndim)
cit = _center_is_true(structure, origin)
if isinstance(output, numpy.ndarray):
if numpy.iscomplexobj(output):
raise TypeError('Complex output type not supported')
else:
output = bool
output = _ni_support._get_output(output, input)
temp_needed = numpy.may_share_memory(input, output)
if temp_needed:
# input and output arrays cannot share memory
temp = output
output = _ni_support._get_output(output.dtype, input)
if iterations == 1:
_nd_image.binary_erosion(input, structure, mask, output,
border_value, origin, invert, cit, 0)
elif cit and not brute_force:
changed, coordinate_list = _nd_image.binary_erosion(
input, structure, mask, output,
border_value, origin, invert, cit, 1)
structure = structure[tuple([slice(None, None, -1)] *
structure.ndim)]
for ii in range(len(origin)):
origin[ii] = -origin[ii]
if not structure.shape[ii] & 1:
origin[ii] -= 1
if mask is not None:
mask = numpy.asarray(mask, dtype=numpy.int8)
if not structure.flags.contiguous:
structure = structure.copy()
_nd_image.binary_erosion2(output, structure, mask, iterations - 1,
origin, invert, coordinate_list)
else:
tmp_in = numpy.empty_like(input, dtype=bool)
tmp_out = output
if iterations >= 1 and not iterations & 1:
tmp_in, tmp_out = tmp_out, tmp_in
changed = _nd_image.binary_erosion(
input, structure, mask, tmp_out,
border_value, origin, invert, cit, 0)
ii = 1
while ii < iterations or (iterations < 1 and changed):
tmp_in, tmp_out = tmp_out, tmp_in
changed = _nd_image.binary_erosion(
tmp_in, structure, mask, tmp_out,
border_value, origin, invert, cit, 0)
ii += 1
if temp_needed:
temp[...] = output
output = temp
return output
def binary_erosion(input, structure=None, iterations=1, mask=None, output=None,
border_value=0, origin=0, brute_force=False):
"""
Multidimensional binary erosion with a given structuring element.
Binary erosion is a mathematical morphology operation used for image
processing.
Parameters
----------
input : array_like
Binary image to be eroded. Non-zero (True) elements form
the subset to be eroded.
structure : array_like, optional
Structuring element used for the erosion. Non-zero elements are
considered True. If no structuring element is provided, an element
is generated with a square connectivity equal to one.
iterations : int, optional
The erosion is repeated `iterations` times (one, by default).
If iterations is less than 1, the erosion is repeated until the
result does not change anymore.
mask : array_like, optional
If a mask is given, only those elements with a True value at
the corresponding mask element are modified at each iteration.
output : ndarray, optional
Array of the same shape as input, into which the output is placed.
By default, a new array is created.
border_value : int (cast to 0 or 1), optional
Value at the border in the output array.
origin : int or tuple of ints, optional
Placement of the filter, by default 0.
brute_force : boolean, optional
Memory condition: if False, only the pixels whose value was changed in
the last iteration are tracked as candidates to be updated (eroded) in
the current iteration; if True all pixels are considered as candidates
for erosion, regardless of what happened in the previous iteration.
False by default.
Returns
-------
binary_erosion : ndarray of bools
Erosion of the input by the structuring element.
See also
--------
grey_erosion, binary_dilation, binary_closing, binary_opening,
generate_binary_structure
Notes
-----
Erosion [1]_ is a mathematical morphology operation [2]_ that uses a
structuring element for shrinking the shapes in an image. The binary
erosion of an image by a structuring element is the locus of the points
where a superimposition of the structuring element centered on the point
is entirely contained in the set of non-zero elements of the image.
References
----------
.. [1] https://en.wikipedia.org/wiki/Erosion_%28morphology%29
.. [2] https://en.wikipedia.org/wiki/Mathematical_morphology
Examples
--------
>>> from scipy import ndimage
>>> import numpy as np
>>> a = np.zeros((7,7), dtype=int)
>>> a[1:6, 2:5] = 1
>>> a
array([[0, 0, 0, 0, 0, 0, 0],
[0, 0, 1, 1, 1, 0, 0],
[0, 0, 1, 1, 1, 0, 0],
[0, 0, 1, 1, 1, 0, 0],
[0, 0, 1, 1, 1, 0, 0],
[0, 0, 1, 1, 1, 0, 0],
[0, 0, 0, 0, 0, 0, 0]])
>>> ndimage.binary_erosion(a).astype(a.dtype)
array([[0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 1, 0, 0, 0],
[0, 0, 0, 1, 0, 0, 0],
[0, 0, 0, 1, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0]])
>>> #Erosion removes objects smaller than the structure
>>> ndimage.binary_erosion(a, structure=np.ones((5,5))).astype(a.dtype)
array([[0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0]])
"""
return _binary_erosion(input, structure, iterations, mask,
output, border_value, origin, 0, brute_force)
def binary_dilation(input, structure=None, iterations=1, mask=None,
output=None, border_value=0, origin=0,
brute_force=False):
"""
Multidimensional binary dilation with the given structuring element.
Parameters
----------
input : array_like
Binary array_like to be dilated. Non-zero (True) elements form
the subset to be dilated.
structure : array_like, optional
Structuring element used for the dilation. Non-zero elements are
considered True. If no structuring element is provided an element
is generated with a square connectivity equal to one.
iterations : int, optional
The dilation is repeated `iterations` times (one, by default).
If iterations is less than 1, the dilation is repeated until the
result does not change anymore. Only an integer of iterations is
accepted.
mask : array_like, optional
If a mask is given, only those elements with a True value at
the corresponding mask element are modified at each iteration.
output : ndarray, optional
Array of the same shape as input, into which the output is placed.
By default, a new array is created.
border_value : int (cast to 0 or 1), optional
Value at the border in the output array.
origin : int or tuple of ints, optional
Placement of the filter, by default 0.
brute_force : boolean, optional
Memory condition: if False, only the pixels whose value was changed in
the last iteration are tracked as candidates to be updated (dilated)
in the current iteration; if True all pixels are considered as
candidates for dilation, regardless of what happened in the previous
iteration. False by default.
Returns
-------
binary_dilation : ndarray of bools
Dilation of the input by the structuring element.
See also
--------
grey_dilation, binary_erosion, binary_closing, binary_opening,
generate_binary_structure
Notes
-----
Dilation [1]_ is a mathematical morphology operation [2]_ that uses a
structuring element for expanding the shapes in an image. The binary
dilation of an image by a structuring element is the locus of the points
covered by the structuring element, when its center lies within the
non-zero points of the image.
References
----------
.. [1] https://en.wikipedia.org/wiki/Dilation_%28morphology%29
.. [2] https://en.wikipedia.org/wiki/Mathematical_morphology
Examples
--------
>>> from scipy import ndimage
>>> import numpy as np
>>> a = np.zeros((5, 5))
>>> a[2, 2] = 1
>>> a
array([[ 0., 0., 0., 0., 0.],
[ 0., 0., 0., 0., 0.],
[ 0., 0., 1., 0., 0.],
[ 0., 0., 0., 0., 0.],
[ 0., 0., 0., 0., 0.]])
>>> ndimage.binary_dilation(a)
array([[False, False, False, False, False],
[False, False, True, False, False],
[False, True, True, True, False],
[False, False, True, False, False],
[False, False, False, False, False]], dtype=bool)
>>> ndimage.binary_dilation(a).astype(a.dtype)
array([[ 0., 0., 0., 0., 0.],
[ 0., 0., 1., 0., 0.],
[ 0., 1., 1., 1., 0.],
[ 0., 0., 1., 0., 0.],
[ 0., 0., 0., 0., 0.]])
>>> # 3x3 structuring element with connectivity 1, used by default
>>> struct1 = ndimage.generate_binary_structure(2, 1)
>>> struct1
array([[False, True, False],
[ True, True, True],
[False, True, False]], dtype=bool)
>>> # 3x3 structuring element with connectivity 2
>>> struct2 = ndimage.generate_binary_structure(2, 2)
>>> struct2
array([[ True, True, True],
[ True, True, True],
[ True, True, True]], dtype=bool)
>>> ndimage.binary_dilation(a, structure=struct1).astype(a.dtype)
array([[ 0., 0., 0., 0., 0.],
[ 0., 0., 1., 0., 0.],
[ 0., 1., 1., 1., 0.],
[ 0., 0., 1., 0., 0.],
[ 0., 0., 0., 0., 0.]])
>>> ndimage.binary_dilation(a, structure=struct2).astype(a.dtype)
array([[ 0., 0., 0., 0., 0.],
[ 0., 1., 1., 1., 0.],
[ 0., 1., 1., 1., 0.],
[ 0., 1., 1., 1., 0.],
[ 0., 0., 0., 0., 0.]])
>>> ndimage.binary_dilation(a, structure=struct1,\\
... iterations=2).astype(a.dtype)
array([[ 0., 0., 1., 0., 0.],
[ 0., 1., 1., 1., 0.],
[ 1., 1., 1., 1., 1.],
[ 0., 1., 1., 1., 0.],
[ 0., 0., 1., 0., 0.]])
"""
input = numpy.asarray(input)
if structure is None:
structure = generate_binary_structure(input.ndim, 1)
origin = _ni_support._normalize_sequence(origin, input.ndim)
structure = numpy.asarray(structure)
structure = structure[tuple([slice(None, None, -1)] *
structure.ndim)]
for ii in range(len(origin)):
origin[ii] = -origin[ii]
if not structure.shape[ii] & 1:
origin[ii] -= 1
return _binary_erosion(input, structure, iterations, mask,
output, border_value, origin, 1, brute_force)
def binary_opening(input, structure=None, iterations=1, output=None,
origin=0, mask=None, border_value=0, brute_force=False):
"""
Multidimensional binary opening with the given structuring element.
The *opening* of an input image by a structuring element is the
*dilation* of the *erosion* of the image by the structuring element.
Parameters
----------
input : array_like
Binary array_like to be opened. Non-zero (True) elements form
the subset to be opened.
structure : array_like, optional
Structuring element used for the opening. Non-zero elements are
considered True. If no structuring element is provided an element
is generated with a square connectivity equal to one (i.e., only
nearest neighbors are connected to the center, diagonally-connected
elements are not considered neighbors).
iterations : int, optional
The erosion step of the opening, then the dilation step are each
repeated `iterations` times (one, by default). If `iterations` is
less than 1, each operation is repeated until the result does
not change anymore. Only an integer of iterations is accepted.
output : ndarray, optional
Array of the same shape as input, into which the output is placed.
By default, a new array is created.
origin : int or tuple of ints, optional
Placement of the filter, by default 0.
mask : array_like, optional
If a mask is given, only those elements with a True value at
the corresponding mask element are modified at each iteration.
.. versionadded:: 1.1.0
border_value : int (cast to 0 or 1), optional
Value at the border in the output array.
.. versionadded:: 1.1.0
brute_force : boolean, optional
Memory condition: if False, only the pixels whose value was changed in
the last iteration are tracked as candidates to be updated in the
current iteration; if true all pixels are considered as candidates for
update, regardless of what happened in the previous iteration.
False by default.
.. versionadded:: 1.1.0
Returns
-------
binary_opening : ndarray of bools
Opening of the input by the structuring element.
See also
--------
grey_opening, binary_closing, binary_erosion, binary_dilation,
generate_binary_structure
Notes
-----
*Opening* [1]_ is a mathematical morphology operation [2]_ that
consists in the succession of an erosion and a dilation of the
input with the same structuring element. Opening, therefore, removes
objects smaller than the structuring element.
Together with *closing* (`binary_closing`), opening can be used for
noise removal.
References
----------
.. [1] https://en.wikipedia.org/wiki/Opening_%28morphology%29
.. [2] https://en.wikipedia.org/wiki/Mathematical_morphology
Examples
--------
>>> from scipy import ndimage
>>> import numpy as np
>>> a = np.zeros((5,5), dtype=int)
>>> a[1:4, 1:4] = 1; a[4, 4] = 1
>>> a
array([[0, 0, 0, 0, 0],
[0, 1, 1, 1, 0],
[0, 1, 1, 1, 0],
[0, 1, 1, 1, 0],
[0, 0, 0, 0, 1]])
>>> # Opening removes small objects
>>> ndimage.binary_opening(a, structure=np.ones((3,3))).astype(int)
array([[0, 0, 0, 0, 0],
[0, 1, 1, 1, 0],
[0, 1, 1, 1, 0],
[0, 1, 1, 1, 0],
[0, 0, 0, 0, 0]])
>>> # Opening can also smooth corners
>>> ndimage.binary_opening(a).astype(int)
array([[0, 0, 0, 0, 0],
[0, 0, 1, 0, 0],
[0, 1, 1, 1, 0],
[0, 0, 1, 0, 0],
[0, 0, 0, 0, 0]])
>>> # Opening is the dilation of the erosion of the input
>>> ndimage.binary_erosion(a).astype(int)
array([[0, 0, 0, 0, 0],
[0, 0, 0, 0, 0],
[0, 0, 1, 0, 0],
[0, 0, 0, 0, 0],
[0, 0, 0, 0, 0]])
>>> ndimage.binary_dilation(ndimage.binary_erosion(a)).astype(int)
array([[0, 0, 0, 0, 0],
[0, 0, 1, 0, 0],
[0, 1, 1, 1, 0],
[0, 0, 1, 0, 0],
[0, 0, 0, 0, 0]])
"""
input = numpy.asarray(input)
if structure is None:
rank = input.ndim
structure = generate_binary_structure(rank, 1)
tmp = binary_erosion(input, structure, iterations, mask, None,
border_value, origin, brute_force)
return binary_dilation(tmp, structure, iterations, mask, output,
border_value, origin, brute_force)
def binary_closing(input, structure=None, iterations=1, output=None,
origin=0, mask=None, border_value=0, brute_force=False):
"""
Multidimensional binary closing with the given structuring element.
The *closing* of an input image by a structuring element is the
*erosion* of the *dilation* of the image by the structuring element.
Parameters
----------
input : array_like
Binary array_like to be closed. Non-zero (True) elements form
the subset to be closed.
structure : array_like, optional
Structuring element used for the closing. Non-zero elements are
considered True. If no structuring element is provided an element
is generated with a square connectivity equal to one (i.e., only
nearest neighbors are connected to the center, diagonally-connected
elements are not considered neighbors).
iterations : int, optional
The dilation step of the closing, then the erosion step are each
repeated `iterations` times (one, by default). If iterations is
less than 1, each operations is repeated until the result does
not change anymore. Only an integer of iterations is accepted.
output : ndarray, optional
Array of the same shape as input, into which the output is placed.
By default, a new array is created.
origin : int or tuple of ints, optional
Placement of the filter, by default 0.
mask : array_like, optional
If a mask is given, only those elements with a True value at
the corresponding mask element are modified at each iteration.
.. versionadded:: 1.1.0
border_value : int (cast to 0 or 1), optional
Value at the border in the output array.
.. versionadded:: 1.1.0
brute_force : boolean, optional
Memory condition: if False, only the pixels whose value was changed in
the last iteration are tracked as candidates to be updated in the
current iteration; if true al pixels are considered as candidates for
update, regardless of what happened in the previous iteration.
False by default.
.. versionadded:: 1.1.0
Returns
-------
binary_closing : ndarray of bools
Closing of the input by the structuring element.
See also
--------
grey_closing, binary_opening, binary_dilation, binary_erosion,
generate_binary_structure
Notes
-----
*Closing* [1]_ is a mathematical morphology operation [2]_ that
consists in the succession of a dilation and an erosion of the
input with the same structuring element. Closing therefore fills
holes smaller than the structuring element.
Together with *opening* (`binary_opening`), closing can be used for
noise removal.
References
----------
.. [1] https://en.wikipedia.org/wiki/Closing_%28morphology%29
.. [2] https://en.wikipedia.org/wiki/Mathematical_morphology
Examples
--------
>>> from scipy import ndimage
>>> import numpy as np
>>> a = np.zeros((5,5), dtype=int)
>>> a[1:-1, 1:-1] = 1; a[2,2] = 0
>>> a
array([[0, 0, 0, 0, 0],
[0, 1, 1, 1, 0],
[0, 1, 0, 1, 0],
[0, 1, 1, 1, 0],
[0, 0, 0, 0, 0]])
>>> # Closing removes small holes
>>> ndimage.binary_closing(a).astype(int)
array([[0, 0, 0, 0, 0],
[0, 1, 1, 1, 0],
[0, 1, 1, 1, 0],
[0, 1, 1, 1, 0],
[0, 0, 0, 0, 0]])
>>> # Closing is the erosion of the dilation of the input
>>> ndimage.binary_dilation(a).astype(int)
array([[0, 1, 1, 1, 0],
[1, 1, 1, 1, 1],
[1, 1, 1, 1, 1],
[1, 1, 1, 1, 1],
[0, 1, 1, 1, 0]])
>>> ndimage.binary_erosion(ndimage.binary_dilation(a)).astype(int)
array([[0, 0, 0, 0, 0],
[0, 1, 1, 1, 0],
[0, 1, 1, 1, 0],
[0, 1, 1, 1, 0],
[0, 0, 0, 0, 0]])
>>> a = np.zeros((7,7), dtype=int)
>>> a[1:6, 2:5] = 1; a[1:3,3] = 0
>>> a
array([[0, 0, 0, 0, 0, 0, 0],
[0, 0, 1, 0, 1, 0, 0],
[0, 0, 1, 0, 1, 0, 0],
[0, 0, 1, 1, 1, 0, 0],
[0, 0, 1, 1, 1, 0, 0],
[0, 0, 1, 1, 1, 0, 0],
[0, 0, 0, 0, 0, 0, 0]])
>>> # In addition to removing holes, closing can also
>>> # coarsen boundaries with fine hollows.
>>> ndimage.binary_closing(a).astype(int)
array([[0, 0, 0, 0, 0, 0, 0],
[0, 0, 1, 0, 1, 0, 0],
[0, 0, 1, 1, 1, 0, 0],
[0, 0, 1, 1, 1, 0, 0],
[0, 0, 1, 1, 1, 0, 0],
[0, 0, 1, 1, 1, 0, 0],
[0, 0, 0, 0, 0, 0, 0]])
>>> ndimage.binary_closing(a, structure=np.ones((2,2))).astype(int)
array([[0, 0, 0, 0, 0, 0, 0],
[0, 0, 1, 1, 1, 0, 0],
[0, 0, 1, 1, 1, 0, 0],
[0, 0, 1, 1, 1, 0, 0],
[0, 0, 1, 1, 1, 0, 0],
[0, 0, 1, 1, 1, 0, 0],
[0, 0, 0, 0, 0, 0, 0]])
"""
input = numpy.asarray(input)
if structure is None:
rank = input.ndim
structure = generate_binary_structure(rank, 1)
tmp = binary_dilation(input, structure, iterations, mask, None,
border_value, origin, brute_force)
return binary_erosion(tmp, structure, iterations, mask, output,
border_value, origin, brute_force)
def binary_hit_or_miss(input, structure1=None, structure2=None,
output=None, origin1=0, origin2=None):
"""
Multidimensional binary hit-or-miss transform.
The hit-or-miss transform finds the locations of a given pattern
inside the input image.
Parameters
----------
input : array_like (cast to booleans)
Binary image where a pattern is to be detected.
structure1 : array_like (cast to booleans), optional
Part of the structuring element to be fitted to the foreground
(non-zero elements) of `input`. If no value is provided, a
structure of square connectivity 1 is chosen.
structure2 : array_like (cast to booleans), optional
Second part of the structuring element that has to miss completely
the foreground. If no value is provided, the complementary of
`structure1` is taken.
output : ndarray, optional
Array of the same shape as input, into which the output is placed.
By default, a new array is created.
origin1 : int or tuple of ints, optional
Placement of the first part of the structuring element `structure1`,
by default 0 for a centered structure.
origin2 : int or tuple of ints, optional
Placement of the second part of the structuring element `structure2`,
by default 0 for a centered structure. If a value is provided for
`origin1` and not for `origin2`, then `origin2` is set to `origin1`.
Returns
-------
binary_hit_or_miss : ndarray
Hit-or-miss transform of `input` with the given structuring
element (`structure1`, `structure2`).
See also
--------
binary_erosion
References
----------
.. [1] https://en.wikipedia.org/wiki/Hit-or-miss_transform
Examples
--------
>>> from scipy import ndimage
>>> import numpy as np
>>> a = np.zeros((7,7), dtype=int)
>>> a[1, 1] = 1; a[2:4, 2:4] = 1; a[4:6, 4:6] = 1
>>> a
array([[0, 0, 0, 0, 0, 0, 0],
[0, 1, 0, 0, 0, 0, 0],
[0, 0, 1, 1, 0, 0, 0],
[0, 0, 1, 1, 0, 0, 0],
[0, 0, 0, 0, 1, 1, 0],
[0, 0, 0, 0, 1, 1, 0],
[0, 0, 0, 0, 0, 0, 0]])
>>> structure1 = np.array([[1, 0, 0], [0, 1, 1], [0, 1, 1]])
>>> structure1
array([[1, 0, 0],
[0, 1, 1],
[0, 1, 1]])
>>> # Find the matches of structure1 in the array a
>>> ndimage.binary_hit_or_miss(a, structure1=structure1).astype(int)
array([[0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0],
[0, 0, 1, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 1, 0, 0],
[0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0]])
>>> # Change the origin of the filter
>>> # origin1=1 is equivalent to origin1=(1,1) here
>>> ndimage.binary_hit_or_miss(a, structure1=structure1,\\
... origin1=1).astype(int)
array([[0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 1, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 1, 0],
[0, 0, 0, 0, 0, 0, 0]])
"""
input = numpy.asarray(input)
if structure1 is None:
structure1 = generate_binary_structure(input.ndim, 1)
if structure2 is None:
structure2 = numpy.logical_not(structure1)
origin1 = _ni_support._normalize_sequence(origin1, input.ndim)
if origin2 is None:
origin2 = origin1
else:
origin2 = _ni_support._normalize_sequence(origin2, input.ndim)
tmp1 = _binary_erosion(input, structure1, 1, None, None, 0, origin1,
0, False)
inplace = isinstance(output, numpy.ndarray)
result = _binary_erosion(input, structure2, 1, None, output, 0,
origin2, 1, False)
if inplace:
numpy.logical_not(output, output)
numpy.logical_and(tmp1, output, output)
else:
numpy.logical_not(result, result)
return numpy.logical_and(tmp1, result)
def binary_propagation(input, structure=None, mask=None,
output=None, border_value=0, origin=0):
"""
Multidimensional binary propagation with the given structuring element.
Parameters
----------
input : array_like
Binary image to be propagated inside `mask`.
structure : array_like, optional
Structuring element used in the successive dilations. The output
may depend on the structuring element, especially if `mask` has
several connex components. If no structuring element is
provided, an element is generated with a squared connectivity equal
to one.
mask : array_like, optional
Binary mask defining the region into which `input` is allowed to
propagate.
output : ndarray, optional
Array of the same shape as input, into which the output is placed.
By default, a new array is created.
border_value : int (cast to 0 or 1), optional
Value at the border in the output array.
origin : int or tuple of ints, optional
Placement of the filter, by default 0.
Returns
-------
binary_propagation : ndarray
Binary propagation of `input` inside `mask`.
Notes
-----
This function is functionally equivalent to calling binary_dilation
with the number of iterations less than one: iterative dilation until
the result does not change anymore.
The succession of an erosion and propagation inside the original image
can be used instead of an *opening* for deleting small objects while
keeping the contours of larger objects untouched.
References
----------
.. [1] http://cmm.ensmp.fr/~serra/cours/pdf/en/ch6en.pdf, slide 15.
.. [2] I.T. Young, J.J. Gerbrands, and L.J. van Vliet, "Fundamentals of
image processing", 1998
ftp://qiftp.tudelft.nl/DIPimage/docs/FIP2.3.pdf
Examples
--------
>>> from scipy import ndimage
>>> import numpy as np
>>> input = np.zeros((8, 8), dtype=int)
>>> input[2, 2] = 1
>>> mask = np.zeros((8, 8), dtype=int)
>>> mask[1:4, 1:4] = mask[4, 4] = mask[6:8, 6:8] = 1
>>> input
array([[0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 1, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0]])
>>> mask
array([[0, 0, 0, 0, 0, 0, 0, 0],
[0, 1, 1, 1, 0, 0, 0, 0],
[0, 1, 1, 1, 0, 0, 0, 0],
[0, 1, 1, 1, 0, 0, 0, 0],
[0, 0, 0, 0, 1, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 1, 1],
[0, 0, 0, 0, 0, 0, 1, 1]])
>>> ndimage.binary_propagation(input, mask=mask).astype(int)
array([[0, 0, 0, 0, 0, 0, 0, 0],
[0, 1, 1, 1, 0, 0, 0, 0],
[0, 1, 1, 1, 0, 0, 0, 0],
[0, 1, 1, 1, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0]])
>>> ndimage.binary_propagation(input, mask=mask,\\
... structure=np.ones((3,3))).astype(int)
array([[0, 0, 0, 0, 0, 0, 0, 0],
[0, 1, 1, 1, 0, 0, 0, 0],
[0, 1, 1, 1, 0, 0, 0, 0],
[0, 1, 1, 1, 0, 0, 0, 0],
[0, 0, 0, 0, 1, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0]])
>>> # Comparison between opening and erosion+propagation
>>> a = np.zeros((6,6), dtype=int)