Python rank.mean函数代码示例

def test_random_sizes():
    # make sure the size is not a problem

    niter = 10
    elem = np.array([[1, 1, 1], [1, 1, 1], [1, 1, 1]], dtype=np.uint8)
    for m, n in np.random.random_integers(1, 100, size=(10, 2)):
        mask = np.ones((m, n), dtype=np.uint8)

        image8 = np.ones((m, n), dtype=np.uint8)
        out8 = np.empty_like(image8)
        rank.mean(image=image8, selem=elem, mask=mask, out=out8,
                  shift_x=0, shift_y=0)
        assert_array_equal(image8.shape, out8.shape)
        rank.mean(image=image8, selem=elem, mask=mask, out=out8,
                  shift_x=+1, shift_y=+1)
        assert_array_equal(image8.shape, out8.shape)

        image16 = np.ones((m, n), dtype=np.uint16)
        out16 = np.empty_like(image8, dtype=np.uint16)
        rank.mean(image=image16, selem=elem, mask=mask, out=out16,
                  shift_x=0, shift_y=0)
        assert_array_equal(image16.shape, out16.shape)
        rank.mean(image=image16, selem=elem, mask=mask, out=out16,
                  shift_x=+1, shift_y=+1)
        assert_array_equal(image16.shape, out16.shape)

        rank.percentile_mean(image=image16, mask=mask, out=out16,
                             selem=elem, shift_x=0, shift_y=0, p0=.1, p1=.9)
        assert_array_equal(image16.shape, out16.shape)
        rank.percentile_mean(image=image16, mask=mask, out=out16,
                             selem=elem, shift_x=+1, shift_y=+1, p0=.1, p1=.9)
        assert_array_equal(image16.shape, out16.shape)

    def split_object(self, labeled_image):
        """ split object when it's necessary
        """
        
        labeled_image = labeled_image.astype(np.uint16)

        labeled_mask = np.zeros_like(labeled_image, dtype=np.uint16)
        labeled_mask[labeled_image != 0] = 1

        #ift structuring element about center point. This only affects eccentric structuring elements (i.e. selem with even num===============================
       
        labeled_image = skr.median(labeled_image, skm.disk(4))
        labeled_mask = np.zeros_like(labeled_image, dtype=np.uint16)
        labeled_mask[labeled_image != 0] = 1
        distance = scipym.distance_transform_edt(labeled_image).astype(np.uint16)
        #=======================================================================
        # binary = np.zeros(np.shape(labeled_image))
        # binary[labeled_image > 0] = 1
        #=======================================================================
        distance = skr.mean(distance, skm.disk(15))
         
        l_max = skr.maximum(distance, skm.disk(5))
        #l_max = skf.peak_local_max(distance, indices=False,labels=labeled_image, footprint=np.ones((3,3)))
        l_max = l_max - distance <= 0
        
        l_max = skr.maximum(l_max.astype(np.uint8), skm.disk(6))
        
       
        
        marker = ndimage.label(l_max)[0]
        split_image = skm.watershed(-distance, marker)
        
        split_image[split_image[0,0] == split_image] = 0
        
        return split_image

def test_selem_dtypes():

    image = np.zeros((5, 5), dtype=np.uint8)
    out = np.zeros_like(image)
    mask = np.ones_like(image, dtype=np.uint8)
    image[2, 2] = 255
    image[2, 3] = 128
    image[1, 2] = 16

    for dtype in (np.uint8, np.uint16, np.int32, np.int64,
                  np.float32, np.float64):
        elem = np.array([[0, 0, 0], [0, 1, 0], [0, 0, 0]], dtype=dtype)
        rank.mean(image=image, selem=elem, out=out, mask=mask,
                  shift_x=0, shift_y=0)
        assert_array_equal(image, out)
        rank.percentile_mean(image=image, selem=elem, out=out, mask=mask,
                             shift_x=0, shift_y=0)
        assert_array_equal(image, out)

def test_16bit():
    image = np.zeros((21, 21), dtype=np.uint16)
    selem = np.ones((3, 3), dtype=np.uint8)

    for bitdepth in range(17):
        value = 2 ** bitdepth - 1
        image[10, 10] = value
        assert rank.minimum(image, selem)[10, 10] == 0
        assert rank.maximum(image, selem)[10, 10] == value
        assert rank.mean(image, selem)[10, 10] == int(value / selem.size)

def test_smallest_selem16():
    # check that min, max and mean returns identity if structuring element
    # contains only central pixel

    image = np.zeros((5, 5), dtype=np.uint16)
    out = np.zeros_like(image)
    mask = np.ones_like(image, dtype=np.uint8)
    image[2, 2] = 255
    image[2, 3] = 128
    image[1, 2] = 16

    elem = np.array([[1]], dtype=np.uint8)
    rank.mean(image=image, selem=elem, out=out, mask=mask,
              shift_x=0, shift_y=0)
    assert_array_equal(image, out)
    rank.minimum(image=image, selem=elem, out=out, mask=mask,
                 shift_x=0, shift_y=0)
    assert_array_equal(image, out)
    rank.maximum(image=image, selem=elem, out=out, mask=mask,
                 shift_x=0, shift_y=0)
    assert_array_equal(image, out)

def test_empty_selem():
    # check that min, max and mean returns zeros if structuring element is empty

    image = np.zeros((5, 5), dtype=np.uint16)
    out = np.zeros_like(image)
    mask = np.ones_like(image, dtype=np.uint8)
    res = np.zeros_like(image)
    image[2, 2] = 255
    image[2, 3] = 128
    image[1, 2] = 16

    elem = np.array([[0, 0, 0], [0, 0, 0]], dtype=np.uint8)

    rank.mean(image=image, selem=elem, out=out, mask=mask,
              shift_x=0, shift_y=0)
    assert_array_equal(res, out)
    rank.minimum(image=image, selem=elem, out=out, mask=mask,
                 shift_x=0, shift_y=0)
    assert_array_equal(res, out)
    rank.maximum(image=image, selem=elem, out=out, mask=mask,
                 shift_x=0, shift_y=0)
    assert_array_equal(res, out)

wide), a small filter radius is sufficient. As the radius is increasing, objects
with a bigger size are filtered as well, such as the camera tripod. The median
filter is commonly used for noise removal because borders are preserved.

Image smoothing
================

The example hereunder shows how a local **mean** smoothes the camera man image.

"""

from skimage.filter.rank import mean

fig = plt.figure(figsize=[10, 7])

loc_mean = mean(nima, disk(10))
plt.subplot(1, 2, 1)
plt.imshow(ima, cmap=plt.cm.gray, vmin=0, vmax=255)
plt.xlabel('original')
plt.subplot(1, 2, 2)
plt.imshow(loc_mean, cmap=plt.cm.gray, vmin=0, vmax=255)
plt.xlabel('local mean $r=10$')

"""

.. image:: PLOT2RST.current_figure

One may be interested in smoothing an image while preserving important borders
(median filters already achieved this), here we use the **bilateral** filter
that restricts the local neighborhood to pixel having a greylevel similar to
the central one.

median filter is often used for noise removal because borders are preserved and
e.g. salt and pepper noise typically does not distort the gray-level.

Image smoothing
================

The example hereunder shows how a local **mean** filter smooths the camera man
image.

"""

from skimage.filter.rank import mean

fig = plt.figure(figsize=[10, 7])

loc_mean = mean(noisy_image, disk(10))

plt.subplot(1, 2, 1)
plt.imshow(noisy_image, vmin=0, vmax=255)
plt.title('Original')
plt.axis('off')

plt.subplot(1, 2, 2)
plt.imshow(loc_mean, vmin=0, vmax=255)
plt.title('Local mean $r=10$')
plt.axis('off')

"""

.. image:: PLOT2RST.current_figure

"""
import numpy as np
import matplotlib.pyplot as plt

from skimage import data
from skimage.morphology import disk
from skimage.filter import rank


image = (data.coins()).astype(np.uint16) * 16
selem = disk(20)

percentile_result = rank.mean_percentile(image, selem=selem, p0=.1, p1=.9)
bilateral_result = rank.mean_bilateral(image, selem=selem, s0=500, s1=500)
normal_result = rank.mean(image, selem=selem)


fig, axes = plt.subplots(nrows=3, figsize=(8, 10))
ax0, ax1, ax2 = axes

ax0.imshow(np.hstack((image, percentile_result)))
ax0.set_title('Percentile mean')
ax0.axis('off')

ax1.imshow(np.hstack((image, bilateral_result)))
ax1.set_title('Bilateral mean')
ax1.axis('off')

ax2.imshow(np.hstack((image, normal_result)))
ax2.set_title('Local mean')

complete image (background and details). Bilateral mean exhibits a high
filtering rate for continuous area (i.e. background) while higher image
frequencies remain untouched.

"""
import numpy as np
import matplotlib.pyplot as plt

from skimage import data
from skimage.morphology import disk
import skimage.filter.rank as rank

a16 = (data.coins()).astype(np.uint16) * 16
selem = disk(20)

f1 = rank.percentile_mean(a16, selem=selem, p0=.1, p1=.9)
f2 = rank.bilateral_mean(a16, selem=selem, s0=500, s1=500)
f3 = rank.mean(a16, selem=selem)

# display results
fig, axes = plt.subplots(nrows=3, figsize=(15, 10))
ax0, ax1, ax2 = axes

ax0.imshow(np.hstack((a16, f1)))
ax0.set_title('percentile mean')
ax1.imshow(np.hstack((a16, f2)))
ax1.set_title('bilateral mean')
ax2.imshow(np.hstack((a16, f3)))
ax2.set_title('local mean')
plt.show()