diff --git a/DEPENDS.txt b/DEPENDS.txt
index aa3cd021..02ee007f 100644
--- a/DEPENDS.txt
+++ b/DEPENDS.txt
@@ -2,7 +2,7 @@ Build Requirements
 ------------------
 * `Python >= 2.6 <http://python.org>`__
 * `Numpy >= 1.6 <http://numpy.scipy.org/>`__
-* `Cython >= 0.19.2 <http://www.cython.org/>`__
+* `Cython >= 0.21 <http://www.cython.org/>`__
 * `Six >=1.3 <https://pypi.python.org/pypi/six>`__
 
 You can use pip to automatically install the base dependencies as follows::
diff --git a/requirements.txt b/requirements.txt
index 189b627b..12ce5fc6 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,4 +1,4 @@
-cython>=0.19.2
+cython>=0.21
 matplotlib>=1.1.0
 numpy>=1.6.1
 scipy>=0.9
diff --git a/skimage/_shared/testing.py b/skimage/_shared/testing.py
index 0f556acf..1c41221b 100644
--- a/skimage/_shared/testing.py
+++ b/skimage/_shared/testing.py
@@ -5,13 +5,13 @@ import os
 import re
 from tempfile import NamedTemporaryFile
 
-from skimage import (
-    data, io, img_as_uint, img_as_float, img_as_int, img_as_ubyte)
 from numpy import testing
 import numpy as np
 from skimage._shared._warnings import expected_warnings
 import warnings
 
+from .. import data, io, img_as_uint, img_as_float, img_as_int, img_as_ubyte
+
 
 SKIP_RE = re.compile("(\s*>>>.*?)(\s*)#\s*skip\s+if\s+(.*)$")
 
diff --git a/skimage/color/adapt_rgb.py b/skimage/color/adapt_rgb.py
index d5966813..8dc02b34 100644
--- a/skimage/color/adapt_rgb.py
+++ b/skimage/color/adapt_rgb.py
@@ -2,8 +2,8 @@ import functools
 
 import numpy as np
 
-from skimage import color
-from skimage.util.dtype import convert
+from .. import color
+from ..util.dtype import convert
 
 
 __all__ = ['adapt_rgb', 'hsv_value', 'each_channel']
diff --git a/skimage/color/colorlabel.py b/skimage/color/colorlabel.py
index ecf56ed9..76cdd6f2 100644
--- a/skimage/color/colorlabel.py
+++ b/skimage/color/colorlabel.py
@@ -3,9 +3,9 @@ import itertools
 
 import numpy as np
 
-from skimage import img_as_float
-from .colorconv import rgb2gray, gray2rgb
+from .. import img_as_float
 from . import rgb_colors
+from .colorconv import rgb2gray, gray2rgb
 
 import six
 from six.moves import zip
diff --git a/skimage/color/delta_e.py b/skimage/color/delta_e.py
index cdd6571a..0511e7a9 100644
--- a/skimage/color/delta_e.py
+++ b/skimage/color/delta_e.py
@@ -21,7 +21,7 @@ from __future__ import division
 
 import numpy as np
 
-from skimage.color.colorconv import lab2lch, _cart2polar_2pi
+from ..color.colorconv import lab2lch, _cart2polar_2pi
 
 
 def deltaE_cie76(lab1, lab2):
diff --git a/skimage/data/__init__.py b/skimage/data/__init__.py
index 81514ce9..2be829ac 100644
--- a/skimage/data/__init__.py
+++ b/skimage/data/__init__.py
@@ -8,8 +8,8 @@ For more images, see
 
 import os as _os
 
+from .. import data_dir
 from ..io import imread, use_plugin
-from skimage import data_dir
 
 
 __all__ = ['load',
diff --git a/skimage/draw/_draw.pyx b/skimage/draw/_draw.pyx
index 649f69f2..d99c10ae 100644
--- a/skimage/draw/_draw.pyx
+++ b/skimage/draw/_draw.pyx
@@ -7,7 +7,7 @@ import numpy as np
 
 cimport numpy as cnp
 from libc.math cimport sqrt, sin, cos, floor, ceil
-from skimage._shared.geometry cimport point_in_polygon
+from .._shared.geometry cimport point_in_polygon
 
 
 def _coords_inside_image(rr, cc, shape, val=None):
diff --git a/skimage/exposure/_adapthist.py b/skimage/exposure/_adapthist.py
index 668d27a6..b71916f5 100644
--- a/skimage/exposure/_adapthist.py
+++ b/skimage/exposure/_adapthist.py
@@ -14,10 +14,10 @@ responsible.  Basically, don't be a jerk, and remember that anything free
 comes with no guarantee.
 """
 import numpy as np
-import skimage
-from skimage.color.adapt_rgb import adapt_rgb, hsv_value
-from skimage.exposure import rescale_intensity
-from skimage.util import view_as_blocks, pad
+from .. import img_as_float, img_as_uint
+from ..color.adapt_rgb import adapt_rgb, hsv_value
+from ..exposure import rescale_intensity
+from ..util import view_as_blocks, pad
 
 
 MAX_REG_X = 16  # max. # contextual regions in x-direction */
@@ -74,11 +74,11 @@ def equalize_adapthist(image, ntiles_x=8, ntiles_y=8, clip_limit=0.01,
     .. [1] http://tog.acm.org/resources/GraphicsGems/gems.html#gemsvi
     .. [2] https://en.wikipedia.org/wiki/CLAHE#CLAHE
     """
-    image = skimage.img_as_uint(image)
+    image = img_as_uint(image)
     image = rescale_intensity(image, out_range=(0, NR_OF_GREY - 1))
     out = _clahe(image, ntiles_x, ntiles_y, clip_limit * nbins, nbins)
     image[:out.shape[0], :out.shape[1]] = out
-    image = skimage.img_as_float(image)
+    image = img_as_float(image)
     return rescale_intensity(image)
 
 
diff --git a/skimage/exposure/exposure.py b/skimage/exposure/exposure.py
index 50f66245..8774cf9b 100644
--- a/skimage/exposure/exposure.py
+++ b/skimage/exposure/exposure.py
@@ -1,8 +1,8 @@
 import warnings
 import numpy as np
 
-from skimage import img_as_float
-from skimage.util.dtype import dtype_range, dtype_limits
+from .. import img_as_float
+from ..util.dtype import dtype_range, dtype_limits
 
 
 __all__ = ['histogram', 'cumulative_distribution', 'equalize_hist',
diff --git a/skimage/feature/_canny.py b/skimage/feature/_canny.py
index 4788b94d..73566d00 100644
--- a/skimage/feature/_canny.py
+++ b/skimage/feature/_canny.py
@@ -16,8 +16,8 @@ import numpy as np
 import scipy.ndimage as ndi
 from scipy.ndimage import (gaussian_filter,
                            generate_binary_structure, binary_erosion, label)
-from skimage import dtype_limits
-from skimage._shared.utils import assert_nD
+from .. import dtype_limits
+from .._shared.utils import assert_nD
 
 
 def smooth_with_function_and_mask(image, function, mask):
diff --git a/skimage/feature/_daisy.py b/skimage/feature/_daisy.py
index d2d03ec7..4ba42f25 100644
--- a/skimage/feature/_daisy.py
+++ b/skimage/feature/_daisy.py
@@ -1,9 +1,9 @@
 import numpy as np
 from scipy import sqrt, pi, arctan2, cos, sin, exp
 from scipy.ndimage import gaussian_filter
-import skimage.color
-from skimage import img_as_float, draw
-from skimage._shared.utils import assert_nD
+from .. import img_as_float, draw
+from ..color import gray2rgb
+from .._shared.utils import assert_nD
 
 
 def daisy(img, step=4, radius=15, rings=3, histograms=8, orientations=8,
@@ -177,7 +177,7 @@ def daisy(img, step=4, radius=15, rings=3, histograms=8, orientations=8,
                 descs[:, :, i:i + orientations] /= norms[:, :, np.newaxis]
 
     if visualize:
-        descs_img = skimage.color.gray2rgb(img)
+        descs_img = gray2rgb(img)
         for i in range(descs.shape[0]):
             for j in range(descs.shape[1]):
                 # Draw center histogram sigma
diff --git a/skimage/feature/_hog.py b/skimage/feature/_hog.py
index 425a0d1b..11f7099d 100644
--- a/skimage/feature/_hog.py
+++ b/skimage/feature/_hog.py
@@ -1,7 +1,7 @@
 import numpy as np
 from scipy import sqrt, pi, arctan2, cos, sin
 from scipy.ndimage import uniform_filter
-from skimage._shared.utils import assert_nD
+from .._shared.utils import assert_nD
 
 
 def hog(image, orientations=9, pixels_per_cell=(8, 8),
@@ -137,7 +137,7 @@ def hog(image, orientations=9, pixels_per_cell=(8, 8),
     hog_image = None
 
     if visualise:
-        from skimage import draw
+        from .. import draw
 
         radius = min(cx, cy) // 2 - 1
         hog_image = np.zeros((sy, sx), dtype=float)
diff --git a/skimage/feature/_texture.pyx b/skimage/feature/_texture.pyx
index 4ee23a7a..5eb91486 100644
--- a/skimage/feature/_texture.pyx
+++ b/skimage/feature/_texture.pyx
@@ -5,7 +5,7 @@
 import numpy as np
 cimport numpy as cnp
 from libc.math cimport sin, cos, abs
-from skimage._shared.interpolation cimport bilinear_interpolation, round
+from .._shared.interpolation cimport bilinear_interpolation, round
 
 
 def _glcm_loop(cnp.uint8_t[:, ::1] image, double[:] distances,
diff --git a/skimage/feature/blob.py b/skimage/feature/blob.py
index acc8f9c5..bc93d265 100644
--- a/skimage/feature/blob.py
+++ b/skimage/feature/blob.py
@@ -5,11 +5,11 @@ import itertools as itt
 import math
 from math import sqrt, hypot, log
 from numpy import arccos
-from skimage.util import img_as_float
+from ..util import img_as_float
 from .peak import peak_local_max
 from ._hessian_det_appx import _hessian_matrix_det
-from skimage.transform import integral_image
-from skimage._shared.utils import assert_nD
+from ..transform import integral_image
+from .._shared.utils import assert_nD
 
 
 # This basic blob detection algorithm is based on:
diff --git a/skimage/feature/brief.py b/skimage/feature/brief.py
index d7104051..783cdbd0 100644
--- a/skimage/feature/brief.py
+++ b/skimage/feature/brief.py
@@ -5,7 +5,7 @@ from .util import (DescriptorExtractor, _mask_border_keypoints,
                    _prepare_grayscale_input_2D)
 
 from .brief_cy import _brief_loop
-from skimage._shared.utils import assert_nD
+from .._shared.utils import assert_nD
 
 
 class BRIEF(DescriptorExtractor):
diff --git a/skimage/feature/censure.py b/skimage/feature/censure.py
index aff923c5..d75c03ca 100644
--- a/skimage/feature/censure.py
+++ b/skimage/feature/censure.py
@@ -1,15 +1,13 @@
 import numpy as np
 from scipy.ndimage.filters import maximum_filter, minimum_filter, convolve
 
-from skimage.feature.util import FeatureDetector, _prepare_grayscale_input_2D
-
-from skimage.transform import integral_image
-from skimage.feature import structure_tensor
-from skimage.morphology import octagon, star
-from skimage.feature.util import _mask_border_keypoints
-
-from skimage.feature.censure_cy import _censure_dob_loop
-from skimage._shared.utils import assert_nD
+from ..transform import integral_image
+from ..feature import structure_tensor
+from ..morphology import octagon, star
+from ..feature.censure_cy import _censure_dob_loop
+from ..feature.util import (FeatureDetector, _prepare_grayscale_input_2D,
+                            _mask_border_keypoints)
+from .._shared.utils import assert_nD
 
 # The paper(Reference [1]) mentions the sizes of the Octagon shaped filter
 # kernel for the first seven scales only. The sizes of the later scales
diff --git a/skimage/feature/corner.py b/skimage/feature/corner.py
index 630f3603..2253c0ec 100644
--- a/skimage/feature/corner.py
+++ b/skimage/feature/corner.py
@@ -2,10 +2,10 @@ import numpy as np
 from scipy import ndimage
 from scipy import stats
 
-from skimage.util import img_as_float, pad
-from skimage.feature import peak_local_max
-from skimage.feature.util import _prepare_grayscale_input_2D
-from skimage.feature.corner_cy import _corner_fast
+from ..util import img_as_float, pad
+from ..feature import peak_local_max
+from ..feature.util import _prepare_grayscale_input_2D
+from ..feature.corner_cy import _corner_fast
 from ._hessian_det_appx import _hessian_matrix_det
 from ..transform import integral_image
 from .._shared.utils import safe_as_int
diff --git a/skimage/feature/corner_cy.pyx b/skimage/feature/corner_cy.pyx
index 7aef99e9..cef104e0 100644
--- a/skimage/feature/corner_cy.pyx
+++ b/skimage/feature/corner_cy.pyx
@@ -7,8 +7,8 @@ cimport numpy as cnp
 from libc.float cimport DBL_MAX
 from libc.math cimport atan2
 
-from skimage.util import img_as_float, pad
-from skimage.color import rgb2grey
+from ..util import img_as_float, pad
+from ..color import rgb2grey
 
 from .util import _prepare_grayscale_input_2D
 
diff --git a/skimage/feature/orb.py b/skimage/feature/orb.py
index 25fa163f..b8f2a89e 100644
--- a/skimage/feature/orb.py
+++ b/skimage/feature/orb.py
@@ -1,13 +1,13 @@
 import numpy as np
 
-from skimage.feature.util import (FeatureDetector, DescriptorExtractor,
-                                  _mask_border_keypoints,
-                                  _prepare_grayscale_input_2D)
+from ..feature.util import (FeatureDetector, DescriptorExtractor,
+                            _mask_border_keypoints,
+                            _prepare_grayscale_input_2D)
 
-from skimage.feature import (corner_fast, corner_orientations, corner_peaks,
+from ..feature import (corner_fast, corner_orientations, corner_peaks,
                              corner_harris)
-from skimage.transform import pyramid_gaussian
-from skimage._shared.utils import assert_nD
+from ..transform import pyramid_gaussian
+from .._shared.utils import assert_nD
 
 from .orb_cy import _orb_loop
 
diff --git a/skimage/feature/orb_cy.pyx b/skimage/feature/orb_cy.pyx
index c5129e85..49c4e650 100644
--- a/skimage/feature/orb_cy.pyx
+++ b/skimage/feature/orb_cy.pyx
@@ -6,12 +6,12 @@
 import os
 import numpy as np
 
-from skimage import data_dir
+from .. import data_dir
 
 cimport numpy as cnp
 from libc.math cimport sin, cos
 
-from skimage._shared.interpolation cimport round
+from .._shared.interpolation cimport round
 
 POS = np.loadtxt(os.path.join(data_dir, "orb_descriptor_positions.txt"),
                  dtype=np.int8)
diff --git a/skimage/feature/template.py b/skimage/feature/template.py
index 9c1ed35e..7aad0dfb 100644
--- a/skimage/feature/template.py
+++ b/skimage/feature/template.py
@@ -1,8 +1,8 @@
 import numpy as np
 from scipy.signal import fftconvolve
 
-from skimage.util import pad
-from skimage._shared.utils import assert_nD
+from ..util import pad
+from .._shared.utils import assert_nD
 
 
 def _window_sum_2d(image, window_shape):
diff --git a/skimage/feature/texture.py b/skimage/feature/texture.py
index 45d97b97..7e23f0be 100644
--- a/skimage/feature/texture.py
+++ b/skimage/feature/texture.py
@@ -3,7 +3,7 @@ Methods to characterize image textures.
 """
 
 import numpy as np
-from skimage._shared.utils import assert_nD
+from .._shared.utils import assert_nD
 from ._texture import _glcm_loop, _local_binary_pattern
 
 
diff --git a/skimage/feature/util.py b/skimage/feature/util.py
index e70be719..b0c66986 100644
--- a/skimage/feature/util.py
+++ b/skimage/feature/util.py
@@ -1,7 +1,7 @@
 import numpy as np
 
-from skimage.util import img_as_float
-from skimage._shared.utils import assert_nD
+from ..util import img_as_float
+from .._shared.utils import assert_nD
 
 
 class FeatureDetector(object):
diff --git a/skimage/filter/__init__.py b/skimage/filter/__init__.py
index 93975a96..5d43f69d 100644
--- a/skimage/filter/__init__.py
+++ b/skimage/filter/__init__.py
@@ -1,4 +1,4 @@
-from skimage._shared.utils import skimage_deprecation
+from .._shared.utils import skimage_deprecation
 from warnings import warn
 
 global _import_warned
diff --git a/skimage/filters/__init__.py b/skimage/filters/__init__.py
index 169b4132..aeba00f7 100644
--- a/skimage/filters/__init__.py
+++ b/skimage/filters/__init__.py
@@ -13,8 +13,8 @@ from .thresholding import (threshold_adaptive, threshold_otsu, threshold_yen,
 from . import rank
 from .rank import median
 
-from skimage._shared.utils import deprecated
-from skimage import restoration
+from .._shared.utils import deprecated
+from .. import restoration
 denoise_bilateral = deprecated('skimage.restoration.denoise_bilateral')\
                         (restoration.denoise_bilateral)
 denoise_tv_bregman = deprecated('skimage.restoration.denoise_tv_bregman')\
@@ -26,7 +26,7 @@ denoise_tv_chambolle = deprecated('skimage.restoration.denoise_tv_chambolle')\
 @deprecated
 def canny(*args, **kwargs):
     # Hack to avoid circular import
-    from skimage.feature._canny import canny as canny_
+    from ..feature._canny import canny as canny_
     return canny_(*args, **kwargs)
 
 
diff --git a/skimage/filters/_gabor.py b/skimage/filters/_gabor.py
index 015d0566..862a593c 100644
--- a/skimage/filters/_gabor.py
+++ b/skimage/filters/_gabor.py
@@ -1,6 +1,6 @@
 import numpy as np
 from scipy import ndimage
-from skimage._shared.utils import assert_nD
+from .._shared.utils import assert_nD
 
 
 __all__ = ['gabor_kernel', 'gabor_filter']
diff --git a/skimage/filters/edges.py b/skimage/filters/edges.py
index e382bc95..1eeed4de 100644
--- a/skimage/filters/edges.py
+++ b/skimage/filters/edges.py
@@ -10,8 +10,8 @@ Original author: Lee Kamentsky
 
 """
 import numpy as np
-from skimage import img_as_float
-from skimage._shared.utils import assert_nD, deprecated
+from .. import img_as_float
+from .._shared.utils import assert_nD, deprecated
 from scipy.ndimage import convolve, binary_erosion, generate_binary_structure
 
 
diff --git a/skimage/filters/lpi_filter.py b/skimage/filters/lpi_filter.py
index e160407a..12943714 100644
--- a/skimage/filters/lpi_filter.py
+++ b/skimage/filters/lpi_filter.py
@@ -5,7 +5,7 @@
 
 import numpy as np
 from scipy.fftpack import ifftshift
-from skimage._shared.utils import assert_nD
+from .._shared.utils import assert_nD
 
 eps = np.finfo(float).eps
 
diff --git a/skimage/filters/rank/_percentile.py b/skimage/filters/rank/_percentile.py
index e57f5df1..918ad348 100644
--- a/skimage/filters/rank/_percentile.py
+++ b/skimage/filters/rank/_percentile.py
@@ -23,7 +23,7 @@ References
 """
 
 import numpy as np
-from skimage._shared.utils import assert_nD
+from ..._shared.utils import assert_nD
 
 from . import percentile_cy
 from .generic import _handle_input
diff --git a/skimage/filters/rank/bilateral.py b/skimage/filters/rank/bilateral.py
index 25fe45b6..48e350b8 100644
--- a/skimage/filters/rank/bilateral.py
+++ b/skimage/filters/rank/bilateral.py
@@ -24,8 +24,8 @@ References
 """
 
 import numpy as np
-from skimage import img_as_ubyte
-from skimage._shared.utils import assert_nD
+from ... import img_as_ubyte
+from ..._shared.utils import assert_nD
 
 from . import bilateral_cy
 from .generic import _handle_input
diff --git a/skimage/filters/rank/generic.py b/skimage/filters/rank/generic.py
index 7a3be5d7..d444a6a5 100644
--- a/skimage/filters/rank/generic.py
+++ b/skimage/filters/rank/generic.py
@@ -18,8 +18,8 @@ References
 
 import warnings
 import numpy as np
-from skimage import img_as_ubyte
-from skimage._shared.utils import assert_nD
+from ... import img_as_ubyte
+from ..._shared.utils import assert_nD
 
 from . import generic_cy
 
diff --git a/skimage/filters/thresholding.py b/skimage/filters/thresholding.py
index c95e56d2..74c5fc14 100644
--- a/skimage/filters/thresholding.py
+++ b/skimage/filters/thresholding.py
@@ -5,8 +5,8 @@ __all__ = ['threshold_adaptive',
 
 import numpy as np
 import scipy.ndimage
-from skimage.exposure import histogram
-from skimage._shared.utils import assert_nD
+from ..exposure import histogram
+from .._shared.utils import assert_nD
 
 
 def threshold_adaptive(image, block_size, method='gaussian', offset=0,
diff --git a/skimage/io/_io.py b/skimage/io/_io.py
index 71f8f25c..f44bfd8b 100644
--- a/skimage/io/_io.py
+++ b/skimage/io/_io.py
@@ -3,8 +3,8 @@ from io import BytesIO
 import numpy as np
 import six
 
-from skimage.io.manage_plugins import call_plugin
-from skimage.color import rgb2grey
+from ..io.manage_plugins import call_plugin
+from ..color import rgb2grey
 from .util import file_or_url_context
 
 
diff --git a/skimage/io/_plugins/imread_plugin.py b/skimage/io/_plugins/imread_plugin.py
index cb715e57..9311f18f 100644
--- a/skimage/io/_plugins/imread_plugin.py
+++ b/skimage/io/_plugins/imread_plugin.py
@@ -1,6 +1,6 @@
 __all__ = ['imread', 'imsave']
 
-from skimage.util.dtype import convert
+from ...util.dtype import convert
 
 try:
     import imread as _imread
@@ -33,7 +33,7 @@ def imsave(fname, arr, format_str=None):
     arr : ndarray of uint8 or uint16
         Array (image) to save.
     format_str: str,optional
-        Format to save as. 
+        Format to save as.
 
     Notes
     -----
diff --git a/skimage/io/_plugins/pil_plugin.py b/skimage/io/_plugins/pil_plugin.py
index 9f9118cf..09d51c7a 100644
--- a/skimage/io/_plugins/pil_plugin.py
+++ b/skimage/io/_plugins/pil_plugin.py
@@ -4,9 +4,8 @@ import numpy as np
 from six import string_types
 from PIL import Image
 
-from skimage.util import img_as_ubyte, img_as_uint
-from skimage.external.tifffile import (
-    imread as tif_imread, imsave as tif_imsave)
+from ...util import img_as_ubyte, img_as_uint
+from ...external.tifffile import imread as tif_imread, imsave as tif_imsave
 
 
 def imread(fname, dtype=None, img_num=None, **kwargs):
diff --git a/skimage/io/_plugins/skivi.py b/skimage/io/_plugins/skivi.py
index fcfe8bc6..ee7b421d 100644
--- a/skimage/io/_plugins/skivi.py
+++ b/skimage/io/_plugins/skivi.py
@@ -209,7 +209,7 @@ class SkiviImageWindow(QMainWindow):
         self.rgb_hsv_disp.update_vals((x, y, r, g, b, h, s, v))
 
     def save_to_stack(self):
-        from skimage import io
+        from ... import io
         img = self.arr.copy()
         io.push(img)
         msg = dedent('''
@@ -227,7 +227,7 @@ class SkiviImageWindow(QMainWindow):
         dialog.exec_()
 
     def save_to_file(self):
-        from skimage import io
+        from ... import io
         filename = str(QtGui.QFileDialog.getSaveFileName())
         if len(filename) == 0:
             return
diff --git a/skimage/io/_plugins/tifffile_plugin.py b/skimage/io/_plugins/tifffile_plugin.py
index efdddf1b..a3a766f1 100644
--- a/skimage/io/_plugins/tifffile_plugin.py
+++ b/skimage/io/_plugins/tifffile_plugin.py
@@ -1 +1 @@
-from skimage.external.tifffile import imread, imsave
+from ...external.tifffile import imread, imsave
diff --git a/skimage/io/_plugins/util.py b/skimage/io/_plugins/util.py
index 98dd4f87..609680d8 100644
--- a/skimage/io/_plugins/util.py
+++ b/skimage/io/_plugins/util.py
@@ -2,7 +2,7 @@ import numpy as np
 from . import _colormixer
 from . import _histograms
 import threading
-from skimage.util import img_as_ubyte
+from ...util import img_as_ubyte
 
 # utilities to make life easier for plugin writers.
 
diff --git a/skimage/io/collection.py b/skimage/io/collection.py
index 20bfb2bf..da2bfda8 100644
--- a/skimage/io/collection.py
+++ b/skimage/io/collection.py
@@ -11,7 +11,7 @@ import numpy as np
 import six
 from PIL import Image
 
-from skimage.external.tifffile import TiffFile
+from ..external.tifffile import TiffFile
 
 
 __all__ = ['MultiImage', 'ImageCollection', 'concatenate_images',
diff --git a/skimage/measure/_pnpoly.pyx b/skimage/measure/_pnpoly.pyx
index 90d990ce..d3c52451 100644
--- a/skimage/measure/_pnpoly.pyx
+++ b/skimage/measure/_pnpoly.pyx
@@ -5,7 +5,7 @@
 import numpy as np
 
 cimport numpy as cnp
-from skimage._shared.geometry cimport point_in_polygon, points_in_polygon
+from .._shared.geometry cimport point_in_polygon, points_in_polygon
 
 
 def grid_points_in_poly(shape, verts):
diff --git a/skimage/measure/block.py b/skimage/measure/block.py
index a670a5fd..1691bef3 100644
--- a/skimage/measure/block.py
+++ b/skimage/measure/block.py
@@ -1,5 +1,5 @@
 import numpy as np
-from skimage.util import view_as_blocks, pad
+from ..util import view_as_blocks, pad
 
 
 def block_reduce(image, block_size, func=np.sum, cval=0):
diff --git a/skimage/morphology/__init__.py b/skimage/morphology/__init__.py
index 5b659093..9bf311c4 100644
--- a/skimage/morphology/__init__.py
+++ b/skimage/morphology/__init__.py
@@ -11,7 +11,7 @@ from .greyreconstruct import reconstruction
 from .misc import remove_small_objects
 
 from ..measure._label import label
-from skimage._shared.utils import deprecated as _deprecated
+from .._shared.utils import deprecated as _deprecated
 label = _deprecated('skimage.measure.label')(label)
 
 
diff --git a/skimage/morphology/_skeletonize_cy.pyx b/skimage/morphology/_skeletonize_cy.pyx
index c4471a11..8dc8eb03 100644
--- a/skimage/morphology/_skeletonize_cy.pyx
+++ b/skimage/morphology/_skeletonize_cy.pyx
@@ -15,7 +15,6 @@ Original author: Lee Kamentsky
 '''
 
 import numpy as np
-
 cimport numpy as cnp
 
 
diff --git a/skimage/morphology/convex_hull.py b/skimage/morphology/convex_hull.py
index edc49d4b..5926e1e0 100644
--- a/skimage/morphology/convex_hull.py
+++ b/skimage/morphology/convex_hull.py
@@ -4,7 +4,7 @@ import numpy as np
 from ..measure import grid_points_in_poly
 from ._convex_hull import possible_hull
 from ..measure._label import label
-from skimage.util import unique_rows
+from ..util import unique_rows
 
 
 def convex_hull_image(image):
diff --git a/skimage/morphology/grey.py b/skimage/morphology/grey.py
index 8ab162cf..0642a104 100644
--- a/skimage/morphology/grey.py
+++ b/skimage/morphology/grey.py
@@ -2,7 +2,6 @@
 Grayscale morphological operations
 """
 import functools
-
 import numpy as np
 from scipy import ndimage as nd
 from .misc import default_selem
diff --git a/skimage/morphology/greyreconstruct.py b/skimage/morphology/greyreconstruct.py
index 3e147e29..47f1f42d 100644
--- a/skimage/morphology/greyreconstruct.py
+++ b/skimage/morphology/greyreconstruct.py
@@ -11,7 +11,7 @@ Original author: Lee Kamentsky
 """
 import numpy as np
 
-from skimage.filters._rank_order import rank_order
+from ..filters._rank_order import rank_order
 
 
 def reconstruction(seed, mask, method='dilation', selem=None, offset=None):
diff --git a/skimage/morphology/selem.py b/skimage/morphology/selem.py
index f75022ab..937ff45d 100644
--- a/skimage/morphology/selem.py
+++ b/skimage/morphology/selem.py
@@ -5,7 +5,7 @@
 
 import numpy as np
 from scipy import ndimage
-from skimage import draw
+from .. import draw
 
 def square(width, dtype=np.uint8):
     """Generates a flat, square-shaped structuring element.
diff --git a/skimage/novice/_novice.py b/skimage/novice/_novice.py
index 03422b2e..cac72ee2 100644
--- a/skimage/novice/_novice.py
+++ b/skimage/novice/_novice.py
@@ -4,11 +4,10 @@ from collections import namedtuple
 from io import BytesIO
 
 import numpy as np
-from skimage import io
-from skimage import img_as_ubyte
-from skimage.transform import resize
-from skimage.color import color_dict
-from skimage.io.util import file_or_url_context, is_url
+from .. import io, img_as_ubyte
+from ..transform import resize
+from ..color import color_dict
+from ..io.util import file_or_url_context, is_url
 
 import six
 from six.moves.urllib_parse import urlparse
diff --git a/skimage/restoration/_denoise.py b/skimage/restoration/_denoise.py
index fb599a64..10de6c68 100644
--- a/skimage/restoration/_denoise.py
+++ b/skimage/restoration/_denoise.py
@@ -1,8 +1,7 @@
 # coding: utf-8
 import numpy as np
-from skimage import img_as_float
-from skimage.restoration._denoise_cy import (_denoise_bilateral,
-                                             _denoise_tv_bregman)
+from .. import img_as_float
+from ..restoration._denoise_cy import _denoise_bilateral, _denoise_tv_bregman
 
 
 def denoise_bilateral(image, win_size=5, sigma_range=None, sigma_spatial=1,
diff --git a/skimage/restoration/_denoise_cy.pyx b/skimage/restoration/_denoise_cy.pyx
index 34404dce..c3faf355 100644
--- a/skimage/restoration/_denoise_cy.pyx
+++ b/skimage/restoration/_denoise_cy.pyx
@@ -8,8 +8,8 @@ import numpy as np
 from libc.math cimport exp, fabs, sqrt
 from libc.stdlib cimport malloc, free
 from libc.float cimport DBL_MAX
-from skimage._shared.interpolation cimport get_pixel3d
-from skimage.util import img_as_float
+from .._shared.interpolation cimport get_pixel3d
+from ..util import img_as_float
 
 
 cdef inline double _gaussian_weight(double sigma, double value):
diff --git a/skimage/segmentation/_felzenszwalb_cy.pyx b/skimage/segmentation/_felzenszwalb_cy.pyx
index 80afaedb..37229225 100644
--- a/skimage/segmentation/_felzenszwalb_cy.pyx
+++ b/skimage/segmentation/_felzenszwalb_cy.pyx
@@ -7,7 +7,7 @@ import scipy
 
 cimport cython
 cimport numpy as cnp
-from skimage.measure._ccomp cimport find_root, join_trees
+from ..measure._ccomp cimport find_root, join_trees
 
 from ..util import img_as_float
 
diff --git a/skimage/segmentation/_join.py b/skimage/segmentation/_join.py
index 5cceeb5b..94769be7 100644
--- a/skimage/segmentation/_join.py
+++ b/skimage/segmentation/_join.py
@@ -1,5 +1,5 @@
 import numpy as np
-from skimage._shared.utils import deprecated
+from .._shared.utils import deprecated
 
 
 def join_segmentations(s1, s2):
diff --git a/skimage/segmentation/_slic.pyx b/skimage/segmentation/_slic.pyx
index 766cd317..1418e902 100644
--- a/skimage/segmentation/_slic.pyx
+++ b/skimage/segmentation/_slic.pyx
@@ -8,7 +8,7 @@ from cpython cimport bool
 import numpy as np
 cimport numpy as cnp
 
-from skimage.util import regular_grid
+from ..util import regular_grid
 
 
 def _slic_cython(double[:, :, :, ::1] image_zyx,
@@ -32,7 +32,7 @@ def _slic_cython(double[:, :, :, ::1] image_zyx,
     spacing : 1D array of double, shape (3,)
         The voxel spacing along each image dimension. This parameter
         controls the weights of the distances along z, y, and x during
-        k-means clustering.        
+        k-means clustering.
     slic_zero : bool
         True to run SLIC-zero, False to run original SLIC.
 
@@ -178,7 +178,7 @@ def _slic_cython(double[:, :, :, ::1] image_zyx,
                         for c in range(3, n_features):
                             dist_color += (image_zyx[z, y, x, c - 3] -
                                            segments[k, c]) ** 2
-                        
+
                         # The reference implementation seems to only change
                         # the color if it increases from previous iteration
                         if max_dist_color[k] < dist_color:
diff --git a/skimage/segmentation/slic_superpixels.py b/skimage/segmentation/slic_superpixels.py
index 5671203e..08f4f828 100644
--- a/skimage/segmentation/slic_superpixels.py
+++ b/skimage/segmentation/slic_superpixels.py
@@ -5,10 +5,10 @@ import numpy as np
 from scipy import ndimage
 import warnings
 
-from skimage.util import img_as_float, regular_grid
-from skimage.segmentation._slic import (_slic_cython,
-                                        _enforce_label_connectivity_cython)
-from skimage.color import rgb2lab
+from ..util import img_as_float, regular_grid
+from ..segmentation._slic import (_slic_cython,
+                                  _enforce_label_connectivity_cython)
+from ..color import rgb2lab
 
 
 def slic(image, n_segments=100, compactness=10., max_iter=10, sigma=0,
diff --git a/skimage/transform/_hough_transform.pyx b/skimage/transform/_hough_transform.pyx
index b1602f74..e51085cb 100644
--- a/skimage/transform/_hough_transform.pyx
+++ b/skimage/transform/_hough_transform.pyx
@@ -10,12 +10,12 @@ cimport cython
 from libc.math cimport abs, fabs, sqrt, ceil, atan2, M_PI
 from libc.stdlib cimport rand
 
-from skimage.draw import circle_perimeter
+from ..draw import circle_perimeter
 
 cdef double PI_2 = 1.5707963267948966
 cdef double NEG_PI_2 = -PI_2
 
-from skimage._shared.interpolation cimport round
+from .._shared.interpolation cimport round
 
 
 def _hough_circle(cnp.ndarray img,
diff --git a/skimage/transform/_warps_cy.pyx b/skimage/transform/_warps_cy.pyx
index 47a28e35..27b6c95a 100644
--- a/skimage/transform/_warps_cy.pyx
+++ b/skimage/transform/_warps_cy.pyx
@@ -4,10 +4,10 @@
 #cython: wraparound=False
 import numpy as np
 cimport numpy as cnp
-from skimage._shared.interpolation cimport (nearest_neighbour_interpolation,
-                                            bilinear_interpolation,
-                                            biquadratic_interpolation,
-                                            bicubic_interpolation)
+from .._shared.interpolation cimport (nearest_neighbour_interpolation,
+                                      bilinear_interpolation,
+                                      biquadratic_interpolation,
+                                      bicubic_interpolation)
 
 
 cdef inline void _matrix_transform(double x, double y, double* H, double *x_,
diff --git a/skimage/transform/hough_transform.py b/skimage/transform/hough_transform.py
index cbb4caa6..0760f5e7 100644
--- a/skimage/transform/hough_transform.py
+++ b/skimage/transform/hough_transform.py
@@ -1,6 +1,6 @@
 import numpy as np
 from scipy import ndimage
-from skimage import measure, morphology
+from .. import measure, morphology
 from ._hough_transform import _hough_circle
 
 
diff --git a/skimage/transform/pyramids.py b/skimage/transform/pyramids.py
index 12cc7912..435d60b9 100644
--- a/skimage/transform/pyramids.py
+++ b/skimage/transform/pyramids.py
@@ -1,8 +1,8 @@
 import math
 import numpy as np
 from scipy import ndimage
-from skimage.transform import resize
-from skimage.util import img_as_float
+from ..transform import resize
+from ..util import img_as_float
 
 
 def _smooth(image, sigma, mode, cval):
diff --git a/skimage/viewer/canvastools/linetool.py b/skimage/viewer/canvastools/linetool.py
index 58b05bc4..261d5a7e 100644
--- a/skimage/viewer/canvastools/linetool.py
+++ b/skimage/viewer/canvastools/linetool.py
@@ -1,7 +1,6 @@
 import numpy as np
-
 from matplotlib import lines
-from skimage.viewer.canvastools.base import CanvasToolBase, ToolHandles
+from ...viewer.canvastools.base import CanvasToolBase, ToolHandles
 
 
 __all__ = ['LineTool', 'ThickLineTool']
@@ -200,8 +199,8 @@ class ThickLineTool(LineTool):
 
 
 if __name__ == '__main__':  # pragma: no cover
-    from skimage import data
-    from skimage.viewer import ImageViewer
+    from ... import data
+    from ...viewer import ImageViewer
 
     image = data.camera()
 
diff --git a/skimage/viewer/canvastools/painttool.py b/skimage/viewer/canvastools/painttool.py
index 9f4bb8ec..e8ce8281 100644
--- a/skimage/viewer/canvastools/painttool.py
+++ b/skimage/viewer/canvastools/painttool.py
@@ -3,7 +3,7 @@ import matplotlib.pyplot as plt
 import matplotlib.colors as mcolors
 LABELS_CMAP = mcolors.ListedColormap(['white', 'red', 'dodgerblue', 'gold',
                                       'greenyellow', 'blueviolet'])
-from skimage.viewer.canvastools.base import CanvasToolBase
+from ...viewer.canvastools.base import CanvasToolBase
 
 
 __all__ = ['PaintTool']
@@ -198,8 +198,8 @@ class CenteredWindow(object):
 
 if __name__ == '__main__':  # pragma: no cover
     np.testing.rundocs()
-    from skimage import data
-    from skimage.viewer import ImageViewer
+    from ... import data
+    from ...viewer import ImageViewer
 
     image = data.camera()
 
diff --git a/skimage/viewer/canvastools/recttool.py b/skimage/viewer/canvastools/recttool.py
index 9b6c1c6b..8a895adf 100644
--- a/skimage/viewer/canvastools/recttool.py
+++ b/skimage/viewer/canvastools/recttool.py
@@ -1,6 +1,6 @@
 from matplotlib.widgets import RectangleSelector
-from skimage.viewer.canvastools.base import CanvasToolBase
-from skimage.viewer.canvastools.base import ToolHandles
+from ...viewer.canvastools.base import CanvasToolBase
+from ...viewer.canvastools.base import ToolHandles
 
 
 __all__ = ['RectangleTool']
@@ -33,7 +33,7 @@ class RectangleTool(CanvasToolBase, RectangleSelector):
     ----------
     extents : tuple
         Rectangle extents: (xmin, xmax, ymin, ymax).
-    
+
     Examples
     ----------
     >>> from skimage import data
@@ -41,12 +41,12 @@ class RectangleTool(CanvasToolBase, RectangleSelector):
     >>> from skimage.viewer.canvastools import RectangleTool
     >>> from skimage.draw import line
     >>> from skimage.draw import set_color
- 
+
     >>> viewer = ImageViewer(data.coffee())  # doctest: +SKIP
 
     >>> def print_the_rect(extents):
     ...     global viewer
-    ...     im = viewer.image    
+    ...     im = viewer.image
     ...     coord = np.int64(extents)
     ...     [rr1, cc1] = line(coord[2],coord[0],coord[2],coord[1])
     ...     [rr2, cc2] = line(coord[2],coord[1],coord[3],coord[1])
@@ -57,11 +57,11 @@ class RectangleTool(CanvasToolBase, RectangleSelector):
     ...     set_color(im, (rr3, cc3), [255, 0, 255])
     ...     set_color(im, (rr4, cc4), [0, 0, 0])
     ...     viewer.image=im
-    
+
     >>> rect_tool = RectangleTool(viewer.ax, on_enter=print_the_rect) # doctest: +SKIP
     >>> viewer.show() # doctest: +SKIP
     """
-    
+
     def __init__(self, viewer, on_move=None, on_release=None, on_enter=None,
                  maxdist=10, rect_props=None):
         self._rect = None
@@ -234,8 +234,8 @@ class RectangleTool(CanvasToolBase, RectangleSelector):
 
 
 if __name__ == '__main__':  # pragma: no cover
-    from skimage.viewer import ImageViewer
-    from skimage import data
+    from ...viewer import ImageViewer
+    from ... import data
 
     viewer = ImageViewer(data.camera())
 
diff --git a/skimage/viewer/plugins/canny.py b/skimage/viewer/plugins/canny.py
index 83e80890..84313d02 100644
--- a/skimage/viewer/plugins/canny.py
+++ b/skimage/viewer/plugins/canny.py
@@ -1,7 +1,7 @@
 import numpy as np
 
 import skimage
-from skimage.feature import canny
+from ...feature import canny
 from .overlayplugin import OverlayPlugin
 from ..widgets import Slider, ComboBox
 
diff --git a/skimage/viewer/plugins/color_histogram.py b/skimage/viewer/plugins/color_histogram.py
index d6c6ddfc..09415a83 100644
--- a/skimage/viewer/plugins/color_histogram.py
+++ b/skimage/viewer/plugins/color_histogram.py
@@ -1,7 +1,6 @@
 import numpy as np
 import matplotlib.pyplot as plt
-from skimage import color
-from skimage import exposure
+from ... import color, exposure
 from .plotplugin import PlotPlugin
 from ..canvastools import RectangleTool
 
@@ -92,4 +91,3 @@ def pct_total_area(image, percentile=0.80):
     idx = int((image.size - 1) * percentile)
     sorted_pixels = np.sort(image.flat)
     return sorted_pixels[idx]
-
diff --git a/skimage/viewer/plugins/crop.py b/skimage/viewer/plugins/crop.py
index 29ad5866..04a85321 100644
--- a/skimage/viewer/plugins/crop.py
+++ b/skimage/viewer/plugins/crop.py
@@ -1,6 +1,6 @@
 from .base import Plugin
 from ..canvastools import RectangleTool
-from skimage.viewer.widgets import SaveButtons
+from ...viewer.widgets import SaveButtons
 
 
 __all__ = ['Crop']
diff --git a/skimage/viewer/plugins/lineprofile.py b/skimage/viewer/plugins/lineprofile.py
index 46a0f1d2..c46b878b 100644
--- a/skimage/viewer/plugins/lineprofile.py
+++ b/skimage/viewer/plugins/lineprofile.py
@@ -1,9 +1,8 @@
 from __future__ import division
 
 import numpy as np
-from skimage.util.dtype import dtype_range
-from skimage import draw
-from skimage import measure
+from ...util.dtype import dtype_range
+from ... import draw, measure
 
 from .plotplugin import PlotPlugin
 from ..canvastools import ThickLineTool
@@ -65,7 +64,7 @@ class LineProfile(PlotPlugin):
                                        on_change=self.line_changed)
         self.line_tool.end_points = np.transpose([x, y])
 
-        scan_data = measure.profile_line(image, 
+        scan_data = measure.profile_line(image,
                                          *self.line_tool.end_points[:, ::-1])
         self.scan_data = scan_data
         if scan_data.ndim == 1:
diff --git a/skimage/viewer/plugins/overlayplugin.py b/skimage/viewer/plugins/overlayplugin.py
index 63ff61a3..eb94baa3 100644
--- a/skimage/viewer/plugins/overlayplugin.py
+++ b/skimage/viewer/plugins/overlayplugin.py
@@ -1,11 +1,11 @@
 from warnings import warn
 
-from skimage.util.dtype import dtype_range
+from ...util.dtype import dtype_range
 from .base import Plugin
 from ..utils import ClearColormap, update_axes_image
 
 import six
-from skimage._shared.version_requirements import is_installed
+from ..._shared.version_requirements import is_installed
 
 
 __all__ = ['OverlayPlugin']
diff --git a/skimage/viewer/viewers/core.py b/skimage/viewer/viewers/core.py
index 19112dc1..b85a028f 100644
--- a/skimage/viewer/viewers/core.py
+++ b/skimage/viewer/viewers/core.py
@@ -2,14 +2,14 @@
 ImageViewer class for viewing and interacting with images.
 """
 
-from skimage.viewer.qt import QtWidgets, Qt, Signal
-from skimage import io, img_as_float
-from skimage.util.dtype import dtype_range
-from skimage.exposure import rescale_intensity
 import numpy as np
+from ... import io, img_as_float
+from ...util.dtype import dtype_range
+from ...exposure import rescale_intensity
+from ..qt import QtWidgets, Qt, Signal
 from ..widgets import Slider
-from ..utils import (
-    dialogs, init_qtapp, figimage, start_qtapp, update_axes_image)
+from ..utils import (dialogs, init_qtapp, figimage, start_qtapp,
+                     update_axes_image)
 from ..plugins.base import Plugin
 
 
diff --git a/skimage/viewer/widgets/history.py b/skimage/viewer/widgets/history.py
index ba0f0cd3..3b7f58b0 100644
--- a/skimage/viewer/widgets/history.py
+++ b/skimage/viewer/widgets/history.py
@@ -4,7 +4,7 @@ from ..qt import QtGui, QtCore
 import numpy as np
 
 import skimage
-from skimage import io
+from ... import io, img_as_ubyte
 from .core import BaseWidget
 from ..utils import dialogs
 
@@ -87,7 +87,7 @@ class SaveButtons(BaseWidget):
         image = self.plugin.filtered_image
         if image.dtype == np.bool:
             #TODO: This check/conversion should probably be in `imsave`.
-            image = skimage.img_as_ubyte(image)
+            image = img_as_ubyte(image)
         io.imsave(filename, image)