def greyscale_erode(image, selem, out=None, shift_x=False, shift_y=False):
"""Return greyscale morphological erosion of an image.
Morphological erosion sets a pixel at (i,j) to the minimum over all pixels
in the neighborhood centered at (i,j). Erosion shrinks bright regions and
enlarges dark regions.
Parameters
----------
image : ndarray
The image as a uint8 ndarray.
selem : ndarray
The neighborhood expressed as a 2-D array of 1's and 0's.
out : ndarray
The array to store the result of the morphology. If None is
passed, a new array will be allocated.
shift_x, shift_y : bool
shift structuring element about center point. This only affects
eccentric structuring elements (i.e. selem with even numbered sides).
Returns
-------
eroded : ndarray
The result of the morphological erosion.
Examples
--------
>>> # Erosion shrinks bright regions
>>> from skimage.morphology import square
>>> bright_square = np.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]], dtype=np.uint8)
>>> greyscale_erode(bright_square, square(3))
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]], dtype='uint8')
"""
if image is out:
raise NotImplementedError("In-place erosion not supported!")
try:
import skimage.morphology.cmorph as cmorph
out = cmorph.erode(image,
selem,
out=out,
shift_x=shift_x,
shift_y=shift_y)
return out
except ImportError:
raise ImportError("cmorph extension not available.")
def erosion(image, selem, out=None, shift_x=False, shift_y=False):
"""Return greyscale morphological erosion of an image.
Morphological erosion sets a pixel at (i,j) to the minimum over all pixels
in the neighborhood centered at (i,j). Erosion shrinks bright regions and
enlarges dark regions.
Parameters
----------
image : ndarray
Image array.
selem : ndarray
The neighborhood expressed as a 2-D array of 1's and 0's.
out : ndarray
The array to store the result of the morphology. If None is
passed, a new array will be allocated.
shift_x, shift_y : bool
shift structuring element about center point. This only affects
eccentric structuring elements (i.e. selem with even numbered sides).
Returns
-------
eroded : uint8 array
The result of the morphological erosion.
Examples
--------
>>> # Erosion shrinks bright regions
>>> from skimage.morphology import square
>>> bright_square = np.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]], dtype=np.uint8)
>>> erosion(bright_square, square(3))
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]], dtype='uint8')
"""
if image is out:
raise NotImplementedError("In-place erosion not supported!")
image = skimage.img_as_ubyte(image)
try:
import skimage.morphology.cmorph as cmorph
out = cmorph.erode(image, selem, out=out,
shift_x=shift_x, shift_y=shift_y)
return out;
except ImportError:
raise ImportError("cmorph extension not available.")
def test_compare_with_cmorph_erode():
# compare the result of maximum filter with erode
image = (np.random.random((100, 100)) * 256).astype(np.uint8)
out = np.empty_like(image)
mask = np.ones(image.shape, dtype=np.uint8)
for r in range(1, 20, 1):
elem = np.ones((r, r), dtype=np.uint8)
rank.minimum(image=image, selem=elem, out=out, mask=mask)
cm = cmorph.erode(image=image, selem=elem)
assert_array_equal(out, cm)
def test_compare_with_cmorph_erode():
# compare the result of maximum filter with erode
image = (np.random.random((100, 100)) * 256).astype(np.uint8)
out = np.empty_like(image)
mask = np.ones(image.shape, dtype=np.uint8)
for r in range(1, 20, 1):
elem = np.ones((r, r), dtype=np.uint8)
rank.minimum(image=image, selem=elem, out=out, mask=mask)
cm = cmorph.erode(image=image, selem=elem)
assert_array_equal(out, cm)
