diff --git a/.travis.yml b/.travis.yml
index 1f292dfa..3a061e13 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -3,28 +3,19 @@
 # After changing this file, check it on:
 #   http://lint.travis-ci.org/
 
-
 language: python
 
-python:
-    - 2.6
 
-matrix:
-    include:
-        - python: 2.7
-          env:
-            - PYTHON=python
-            - PYTHONWARNINGS=all
-            - PYTHONX=python
-            - PYVER=2.x
-        - python: 3.2
-          env:
-            - PYTHON=python3
-            - PYTHONWARNINGS=all
-            - PYTHONX=python3
-            - PYVER=3.x
-    exclude:
-        - python: 2.6
+#  Tthe Travis python is set to 3.2 for all builds, since we use the default python for the 3.2 build and the anaconda python otherwise
+python:
+    - 3.2
+
+env:
+    - ENV="python=2.6 numpy=1.6 cython=0.19.2"
+    - ENV="python=2.7 numpy cython"
+    - ENV="python=3.2"
+    - ENV="python=3.3 numpy cython"
+    - ENV="python=3.4 numpy cython"
 
 virtualenv:
     system_site_packages: true
@@ -32,64 +23,90 @@ virtualenv:
 before_install:
     - export DISPLAY=:99.0
     - sh -e /etc/init.d/xvfb start
-
     - sudo apt-get update
 
-    - sudo apt-get install $PYTHON-numpy
-    - wget https://raw.githubusercontent.com/numpy/numpy/master/numpy/_import_tools.py -O /home/travis/virtualenv/python3.2_with_system_site_packages/lib/python3.2/site-packages/numpy/_import_tools.py
-
-    - sudo apt-get install $PYTHON-scipy
-    - sudo apt-get install libfreeimage3
-
-    - if [[ $PYVER == '2.x' ]]; then
-    -   sudo apt-get install $PYTHON-qt4;
-    -   sudo apt-get install $PYTHON-matplotlib;
-    - fi
-    - if [[ $PYVER == '3.x' ]]; then
-    -   sudo apt-get install $PYTHON-pyqt4;
-    -   pip install --use-mirrors matplotlib;
-    - fi
-
-    - pip install pillow
-    - pip install cython
-    - pip install flake8
-    - pip install six
-    - pip install networkx
-
-    - pip install nose-cov
-    - pip install coveralls
-
+    # Python 3.2 is not supported by Miniconda, so we use the package manager for that run.
+    # NumPy has a bug in python 3 that is only fixed in the latest version,
+    #  hence the below wget of numpy/_import_tools.py from github.
+    - if [[ $ENV == python=3.2 ]]; then
+        sudo apt-get install python3-numpy;
+        wget https://raw.githubusercontent.com/numpy/numpy/master/numpy/_import_tools.py -O /home/travis/virtualenv/python3.2_with_system_site_packages/lib/python3.2/site-packages/numpy/_import_tools.py;
+        sudo apt-get install python3-scipy;
+        pip install cython flake8 six;
+      else
+        wget http://repo.continuum.io/miniconda/Miniconda-latest-Linux-x86_64.sh -O miniconda.sh;
+        bash miniconda.sh -b -p $HOME/miniconda;
+        export PATH="$HOME/miniconda/bin:$PATH";
+        hash -r;
+        conda config --set always_yes yes;
+        conda update conda;
+        conda info -a;
+        travis_retry conda create -n test $ENV six scipy pip flake8 nose;
+        source activate test;
+      fi
+    - pip install coveralls pillow
     - python check_bento_build.py
 
 install:
     - tools/header.py "Dependency versions"
     - tools/build_versions.py
-
+    - export PYTHONWARNINGS=all
     - python setup.py build_ext --inplace
 
 script:
-    # Matplotlib settings
-    - mkdir -p $HOME/.matplotlib
-    - touch $HOME/.matplotlib/matplotlibrc
-    - "echo 'backend : Agg' > $HOME/.matplotlib/matplotlibrc"
-    - "echo 'backend.qt4 : PyQt4' >> $HOME/.matplotlib/matplotlibrc"
-
-    # Run all tests
-    - if [[ $PYVER == '3.x' ]]; then
-    -   nosetests --exe -v --with-doctest --with-cov --cov skimage --cov-config=.coveragerc skimage
-    - fi
-    - if [[ $PYVER == '2.x' ]]; then
-    -   nosetests --exe -v --with-doctest skimage
-    - fi
-    # Run all doc examples
-    - export PYTHONPATH=$(pwd):$PYTHONPATH
-    - for f in doc/examples/*.py; do $PYTHONX "$f"; if [ $? -ne 0 ]; then exit 1; fi done
-    - for f in doc/examples/applications/*.py; do $PYTHONX "$f"; if [ $? -ne 0 ]; then exit 1; fi done
+    # Run all tests with minimum dependencies
+    - nosetests --exe -v skimage
 
     # Run pep8 and flake tests
     - flake8 --exit-zero --exclude=test_*,six.py skimage doc/examples viewer_examples
 
+    # Install optional dependencies to get full test coverage
+    # Notes:
+    # - pyfits and imread do NOT support py3.2
+    # - Use the png headers included in anaconda (from matplotlib install)
+    # TODO: Remove the libm removal when anaconda fixes their libraries
+    #   The solution was suggested here
+    #   https://groups.google.com/a/continuum.io/forum/#!topic/anaconda/-DLG2ZdTkw0
+    - if [[ $ENV == python=3.2 ]]; then
+        sudo apt-get install -qq python3-pyqt4;
+        pip install --use-mirrors -q matplotlib;
+        pip install -q networkx;
+      else
+        travis_retry conda install -q matplotlib pyqt networkx;
+        sudo cp ~/miniconda/envs/test/include/png* /usr/include;
+        rm ~/miniconda/envs/test/lib/libm-2.5.so;
+        rm ~/miniconda/envs/test/lib/libm.*;
+        sudo apt-get install -qq libtiff4-dev libwebp-dev xcftools;
+        pip install -q imread;
+        pip install -q pyfits;
+      fi
+    - sudo apt-get install -qq libfreeimage3
+    # TODO: update when SimpleITK become available on py34 or hopefully pip
+    - if [[ $ENV != python=3.4* ]]; then
+        travis_retry easy_install -q SimpleITK;
+      fi
+
+    # Matplotlib settings
+    - export MPL_DIR=$HOME/.config/matplotlib
+    - mkdir -p $MPL_DIR
+    - touch $MPL_DIR/matplotlibrc
+    - "echo 'backend : Agg' > $MPL_DIR/matplotlibrc"
+    - "echo 'backend.qt4 : PyQt4' >> $MPL_DIR/matplotlibrc"
+
+    # Run all doc examples
+    - export PYTHONPATH=$(pwd):$PYTHONPATH
+    - for f in doc/examples/*.py; do python "$f"; if [ $? -ne 0 ]; then exit 1; fi done
+    - for f in doc/examples/applications/*.py; do python "$f"; if [ $? -ne 0 ]; then exit 1; fi done
+
+    # run tests again with optional dependencies to get more coverage
+    # measure coverage on py3.3
+    - if [[ $ENV == python=3.3* ]]; then
+         nosetests --exe -v --with-doctest --with-cov --cover-package skimage;
+      else
+         nosetests --exe -v --with-doctest skimage;
+      fi
+
 after_success:
-    - if [[ $PYVER == '3.x' ]]; then
-    -   coveralls
-    - fi
+    - if [[ $ENV == python=3.3* ]]; then
+          coveralls;
+      fi
diff --git a/skimage/_shared/tests/test_version_requirements.py b/skimage/_shared/tests/test_version_requirements.py
new file mode 100644
index 00000000..59cf5814
--- /dev/null
+++ b/skimage/_shared/tests/test_version_requirements.py
@@ -0,0 +1,42 @@
+"""Tests for the version requirement functions.
+
+"""
+import numpy as np
+from numpy.testing import assert_raises, assert_equal
+import nose
+from skimage._shared import version_requirements as version_req
+
+
+def test_get_module_version():
+    assert version_req.get_module_version('numpy')
+    assert version_req.get_module_version('scipy')
+    assert_raises(ImportError,
+                  lambda: version_req.get_module_version('fakenumpy'))
+
+
+def test_is_installed():
+    assert version_req.is_installed('python', '>=2.6')
+    assert not version_req.is_installed('numpy', '<1.0')
+
+
+def test_require():
+
+    # A function that only runs on Python >2.6 and numpy > 1.5 (should pass)
+    @version_req.require('python', '>2.6')
+    @version_req.require('numpy', '>1.5')
+    def foo():
+        return 1
+
+    assert_equal(foo(), 1)
+
+    # function that requires scipy < 0.1 (should fail)
+    @version_req.require('scipy', '<0.1')
+    def bar():
+        return 0
+
+    assert_raises(ImportError, lambda: bar())
+
+
+def test_get_module():
+    assert_equal(version_req.get_module('numpy'), np)
+    assert_equal(version_req.get_module('nose'), nose)
diff --git a/skimage/_shared/version_requirements.py b/skimage/_shared/version_requirements.py
new file mode 100644
index 00000000..4ebf8ee9
--- /dev/null
+++ b/skimage/_shared/version_requirements.py
@@ -0,0 +1,142 @@
+from distutils.version import LooseVersion
+import functools
+import re
+import sys
+
+
+def _check_version(actver, version, cmp_op):
+    """
+    Check version string of an active module against a required version.
+
+    If dev/prerelease tags result in TypeError for string-number comparison,
+    it is assumed that the dependency is satisfied.
+    Users on dev branches are responsible for keeping their own packages up to
+    date.
+
+    Copyright (C) 2013  The IPython Development Team
+
+    Distributed under the terms of the BSD License.
+    """
+    try:
+        if cmp_op == '>':
+            return LooseVersion(actver) > LooseVersion(version)
+        elif cmp_op == '>=':
+            return LooseVersion(actver) >= LooseVersion(version)
+        elif cmp_op == '=':
+            return LooseVersion(actver) == LooseVersion(version)
+        elif cmp_op == '<':
+            return LooseVersion(actver) < LooseVersion(version)
+        else:
+            return False
+    except TypeError:
+        return True
+
+
+def get_module_version(module_name):
+    """Return module version or None if version can't be retrieved."""
+    mod = __import__(module_name,
+                     fromlist=[module_name.rpartition('.')[-1]])
+    return getattr(mod, '__version__', getattr(mod, 'VERSION', None))
+
+
+def is_installed(name, version=None):
+    """Test if *name* is installed.
+
+    Parameters
+    ----------
+    name : str
+        Name of module or "python"
+    version : str, optional
+        Version string to test against.
+        If version is not None, checking version
+        (must have an attribute named '__version__' or 'VERSION')
+        Version may start with =, >=, > or < to specify the exact requirement
+
+    Returns
+    -------
+    out : bool
+        True if *name* is installed matching the optional version.
+
+    Note
+    ----
+    Original Copyright (C) 2009-2011 Pierre Raybaut
+    Licensed under the terms of the MIT License.
+    """
+    if name.lower() == 'python':
+        actver = sys.version[:6]
+    else:
+        try:
+            actver = get_module_version(name)
+        except ImportError:
+            return False
+    if version is None:
+        return True
+    else:
+        match = re.search('[0-9]', version)
+        assert match is not None, "Invalid version number"
+        symb = version[:match.start()]
+        if not symb:
+            symb = '='
+        assert symb in ('>=', '>', '=', '<'),\
+            "Invalid version condition '%s'" % symb
+        version = version[match.start():]
+        return _check_version(actver, version, symb)
+
+
+def require(name, version=None):
+    """Return decorator that forces a requirement for a function or class.
+
+    Parameters
+    ----------
+    name : str
+        Name of module or "python".
+    version : str, optional
+        Version string to test against.
+        If version is not None, checking version
+        (must have an attribute named '__version__' or 'VERSION')
+        Version may start with =, >=, > or < to specify the exact requirement
+
+    Returns
+    -------
+    func : function
+        A decorator that raises an ImportError if a function is run
+        in the absence of the input dependency.
+    """
+    def decorator(obj):
+        @functools.wraps(obj)
+        def func_wrapped(*args, **kwargs):
+            if is_installed(name, version):
+                return obj(*args, **kwargs)
+            else:
+                msg = '"%s" in "%s" requires "%s'
+                msg = msg % (obj, obj.__module__, name)
+                if not version is None:
+                    msg += " %s" % version
+                raise ImportError(msg + '"')
+        return func_wrapped
+    return decorator
+
+
+def get_module(module_name, version=None):
+    """Return a module object of name *module_name* if installed.
+
+    Parameters
+    ----------
+    module_name : str
+        Name of module.
+    version : str, optional
+        Version string to test against.
+        If version is not None, checking version
+        (must have an attribute named '__version__' or 'VERSION')
+        Version may start with =, >=, > or < to specify the exact requirement
+
+    Returns
+    -------
+    mod : module or None
+        Module if *module_name* is installed matching the optional version
+        or None otherwise.
+    """
+    if not is_installed(module_name, version):
+        return None
+    return __import__(module_name,
+                      fromlist=[module_name.rpartition('.')[-1]])
diff --git a/skimage/exposure/_adapthist.py b/skimage/exposure/_adapthist.py
index 5da50029..9cfc716e 100644
--- a/skimage/exposure/_adapthist.py
+++ b/skimage/exposure/_adapthist.py
@@ -17,7 +17,7 @@ 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
+from skimage.util import view_as_blocks, pad
 
 
 MAX_REG_X = 16  # max. # contextual regions in x-direction */
@@ -125,7 +125,7 @@ def _clahe(image, ntiles_x, ntiles_y, clip_limit, nbins=128):
     if h_inner != image.shape[1] or w_inner != image.shape[0]:
         h_pad = height * ntiles_y - image.shape[0]
         w_pad = width * ntiles_x - image.shape[1]
-        image = np.pad(image, ((0, h_pad), (0, w_pad)), 'reflect')
+        image = pad(image, ((0, h_pad), (0, w_pad)), mode='reflect')
         h_inner, w_inner = image.shape
 
     bin_size = 1 + NR_OF_GREY / nbins
diff --git a/skimage/feature/tests/test_util.py b/skimage/feature/tests/test_util.py
index 2b601b94..f15bcb2a 100644
--- a/skimage/feature/tests/test_util.py
+++ b/skimage/feature/tests/test_util.py
@@ -1,5 +1,8 @@
 import numpy as np
-import matplotlib.pyplot as plt
+try:
+  import matplotlib.pyplot as plt
+except ImportError:
+  plt = None
 from numpy.testing import assert_equal, assert_raises
 
 from skimage.feature.util import (FeatureDetector, DescriptorExtractor,
@@ -39,6 +42,7 @@ def test_mask_border_keypoints():
                  [0, 0, 0, 0, 1])
 
 
+@np.testing.decorators.skipif(plt is None)
 def test_plot_matches():
     fig, ax = plt.subplots(nrows=1, ncols=1)
 
diff --git a/skimage/graph/graph_cut.py b/skimage/graph/graph_cut.py
index 91d64aec..d9fcfdef 100644
--- a/skimage/graph/graph_cut.py
+++ b/skimage/graph/graph_cut.py
@@ -1,4 +1,8 @@
-import networkx as nx
+try:
+    import networkx as nx
+except ImportError:
+    import warnings
+    warnings.warn('"cut_threshold" requires networkx')
 import numpy as np
 
 
diff --git a/skimage/graph/rag.py b/skimage/graph/rag.py
index 84721736..7c1b7f07 100644
--- a/skimage/graph/rag.py
+++ b/skimage/graph/rag.py
@@ -1,4 +1,13 @@
-import networkx as nx
+try:
+    import networkx as nx
+except ImportError:
+    msg = "Graph functions require networkx, which is not installed"
+    class nx:
+        class Graph:
+            def __init__(self, *args, **kwargs):
+                raise ImportError(msg)
+    import warnings
+    warnings.warn(msg)
 import numpy as np
 from scipy.ndimage import filters
 from scipy import ndimage as nd
diff --git a/skimage/graph/tests/test_rag.py b/skimage/graph/tests/test_rag.py
index af7481eb..753bcb74 100644
--- a/skimage/graph/tests/test_rag.py
+++ b/skimage/graph/tests/test_rag.py
@@ -1,5 +1,7 @@
 import numpy as np
 from skimage import graph
+from skimage._shared.version_requirements import is_installed
+from numpy.testing.decorators import skipif
 
 
 def max_edge(g, src, dst, n):
@@ -9,6 +11,7 @@ def max_edge(g, src, dst, n):
     return max(w1, w2)
 
 
+@skipif(not is_installed('networkx'))
 def test_rag_merge():
     g = graph.rag.RAG()
 
@@ -43,6 +46,7 @@ def test_rag_merge():
     assert g.edges() == []
 
 
+@skipif(not is_installed('networkx'))
 def test_threshold_cut():
 
     img = np.zeros((100, 100, 3), dtype='uint8')
diff --git a/skimage/io/_plugins/freeimage_plugin.py b/skimage/io/_plugins/freeimage_plugin.py
index 07e8d313..5ebe8214 100644
--- a/skimage/io/_plugins/freeimage_plugin.py
+++ b/skimage/io/_plugins/freeimage_plugin.py
@@ -85,7 +85,7 @@ def load_freeimage():
         if errors:
             # No freeimage library loaded, and load-errors reported for some
             # candidate libs
-            err_txt = ['%s:\n%s' % (l, str(e.message)) for l, e in errors]
+            err_txt = ['%s:\n%s' % (l, str(e)) for l, e in errors]
             raise RuntimeError('One or more FreeImage libraries were found, but '
                                'could not be loaded due to the following errors:\n'
                                '\n\n'.join(err_txt))
diff --git a/skimage/io/_plugins/imread_plugin.py b/skimage/io/_plugins/imread_plugin.py
index 46382cdf..cb715e57 100644
--- a/skimage/io/_plugins/imread_plugin.py
+++ b/skimage/io/_plugins/imread_plugin.py
@@ -1,6 +1,6 @@
 __all__ = ['imread', 'imsave']
 
-from skimage.utils.dtype import convert
+from skimage.util.dtype import convert
 
 try:
     import imread as _imread
diff --git a/skimage/io/_plugins/pil_plugin.py b/skimage/io/_plugins/pil_plugin.py
index 88e7f04b..e6f9c491 100644
--- a/skimage/io/_plugins/pil_plugin.py
+++ b/skimage/io/_plugins/pil_plugin.py
@@ -21,6 +21,7 @@ def imread(fname, dtype=None):
 
     """
     im = Image.open(fname)
+    fp = im.fp
     if im.mode == 'P':
         if _palette_is_grayscale(im):
             im = im.convert('L')
@@ -35,8 +36,9 @@ def imread(fname, dtype=None):
         im.shape = shape[::-1]
     elif 'A' in im.mode:
         im = im.convert('RGBA')
-
-    return np.array(im, dtype=dtype)
+    im = np.array(im, dtype=dtype)
+    fp.close()
+    return im
 
 
 def _palette_is_grayscale(pil_image):
diff --git a/skimage/io/_plugins/qt_plugin.py b/skimage/io/_plugins/qt_plugin.py
index db4cb4cc..f3a3b8e0 100644
--- a/skimage/io/_plugins/qt_plugin.py
+++ b/skimage/io/_plugins/qt_plugin.py
@@ -158,7 +158,7 @@ def imsave(filename, img, format_str=None):
         qbuffer.open(QtCore.QIODevice.ReadWrite)
         saved = qimg.save(qbuffer, format_str.upper())
         qbuffer.seek(0)
-        filename.write(qbuffer.readAll())
+        filename.write(qbuffer.readAll().data())
         qbuffer.close()
     else:
         saved = qimg.save(filename)
diff --git a/skimage/io/tests/test_imread.py b/skimage/io/tests/test_imread.py
index 25ad870e..a2c32b79 100644
--- a/skimage/io/tests/test_imread.py
+++ b/skimage/io/tests/test_imread.py
@@ -7,6 +7,7 @@ from tempfile import NamedTemporaryFile
 
 from skimage import data_dir
 from skimage.io import imread, imsave, use_plugin, reset_plugins
+import skimage.io as sio
 
 try:
     import imread as _imread
@@ -39,11 +40,13 @@ def test_imread_palette():
     img = imread(os.path.join(data_dir, 'palette_color.png'))
     assert img.ndim == 3
 
+
 @skipif(not imread_available)
 def test_imread_truncated_jpg():
     assert_raises((RuntimeError, ValueError),
                   sio.imread,
-                  os.path.join(si.data_dir, 'truncated.jpg'))
+                  os.path.join(data_dir, 'truncated.jpg'))
+
 
 @skipif(not imread_available)
 def test_bilevel():
diff --git a/skimage/io/tests/test_simpleitk.py b/skimage/io/tests/test_simpleitk.py
index ab8cd592..e7fb1e83 100644
--- a/skimage/io/tests/test_simpleitk.py
+++ b/skimage/io/tests/test_simpleitk.py
@@ -1,6 +1,7 @@
 import os.path
 import numpy as np
 from numpy.testing.decorators import skipif
+from numpy.testing import assert_raises
 
 from tempfile import NamedTemporaryFile
 
@@ -52,12 +53,15 @@ def test_bilevel():
     img = imread(os.path.join(data_dir, 'checker_bilevel.png'))
     np.testing.assert_array_equal(img, expected)
 
-
+"""
+#TODO: This test causes a Segmentation fault
 @skipif(not sitk_available)
 def test_imread_truncated_jpg():
     assert_raises((RuntimeError, ValueError),
-                  sio.imread,
-                  os.path.join(si.data_dir, 'truncated.jpg'))
+                  imread,
+                  os.path.join(data_dir, 'truncated.jpg'))
+"""
+
 
 @skipif(not sitk_available)
 def test_imread_uint16():
diff --git a/skimage/morphology/greyreconstruct.py b/skimage/morphology/greyreconstruct.py
index cea200a4..bce26d6b 100644
--- a/skimage/morphology/greyreconstruct.py
+++ b/skimage/morphology/greyreconstruct.py
@@ -131,7 +131,7 @@ def reconstruction(seed, mask, method='dilation', selem=None, offset=None):
     if selem is None:
         selem = np.ones([3] * seed.ndim, dtype=bool)
     else:
-        selem = selem.astype(bool, copy=True)
+        selem = selem.astype(bool)
 
     if offset is None:
         if not all([d % 2 == 1 for d in selem.shape]):
diff --git a/skimage/morphology/misc.py b/skimage/morphology/misc.py
index 94aadf7a..edf2892b 100644
--- a/skimage/morphology/misc.py
+++ b/skimage/morphology/misc.py
@@ -5,12 +5,13 @@ from .selem import _default_selem
 # Our function names don't exactly correspond to ndimages.
 # This dictionary translates from our names to scipy's.
 funcs = ('erosion', 'dilation', 'opening', 'closing')
-skimage2ndimage = {x: 'grey_' + x for x in funcs}
+skimage2ndimage = dict((x, 'grey_' + x) for x in funcs)
 
 # These function names are the same in ndimage.
 funcs = ('binary_erosion', 'binary_dilation', 'binary_opening',
          'binary_closing', 'black_tophat', 'white_tophat')
-skimage2ndimage.update({x: x for x in funcs})
+skimage2ndimage.update(dict((x, x) for x in funcs))
+
 
 def default_fallback(func):
     """Decorator to fall back on ndimage for images with more than 2 dimensions
diff --git a/skimage/restoration/unwrap.py b/skimage/restoration/unwrap.py
index 085bef0b..f0025775 100644
--- a/skimage/restoration/unwrap.py
+++ b/skimage/restoration/unwrap.py
@@ -84,6 +84,7 @@ def unwrap_phase(image, wrap_around=False):
 
     if np.ma.isMaskedArray(image):
         mask = np.require(image.mask, np.uint8, ['C'])
+        image = image.data
     else:
         mask = np.zeros_like(image, dtype=np.uint8, order='C')
     image_not_masked = np.asarray(image, dtype=np.float64, order='C')
diff --git a/skimage/viewer/__init__.py b/skimage/viewer/__init__.py
index 5eed9589..4bf70a93 100644
--- a/skimage/viewer/__init__.py
+++ b/skimage/viewer/__init__.py
@@ -1 +1,11 @@
+from warnings import warn
+from skimage._shared.version_requirements import is_installed
+
 from .viewers import ImageViewer, CollectionViewer
+from .qt import qt_api
+
+viewer_available = not qt_api is None and is_installed('matplotlib')
+if not viewer_available:
+    warn('Viewer requires matplotlib and Qt')
+
+del qt_api, is_installed, warn
diff --git a/skimage/viewer/canvastools/base.py b/skimage/viewer/canvastools/base.py
index 7f61ce2c..29e6099d 100644
--- a/skimage/viewer/canvastools/base.py
+++ b/skimage/viewer/canvastools/base.py
@@ -1,10 +1,8 @@
 import numpy as np
-
 try:
     from matplotlib import lines
 except ImportError:
-    print("Could not import matplotlib -- skimage.viewer not available.")
-
+    pass
 
 __all__ = ['CanvasToolBase', 'ToolHandles']
 
diff --git a/skimage/viewer/canvastools/linetool.py b/skimage/viewer/canvastools/linetool.py
index fed18383..61d94825 100644
--- a/skimage/viewer/canvastools/linetool.py
+++ b/skimage/viewer/canvastools/linetool.py
@@ -3,8 +3,7 @@ import numpy as np
 try:
     from matplotlib import lines
 except ImportError:
-    print("Could not import matplotlib -- skimage.viewer not available.")
-
+    pass
 from skimage.viewer.canvastools.base import CanvasToolBase, ToolHandles
 
 
diff --git a/skimage/viewer/canvastools/painttool.py b/skimage/viewer/canvastools/painttool.py
index 6af8b5d3..fd994a10 100644
--- a/skimage/viewer/canvastools/painttool.py
+++ b/skimage/viewer/canvastools/painttool.py
@@ -1,9 +1,11 @@
 import numpy as np
-import matplotlib.pyplot as plt
-import matplotlib.colors as mcolors
-LABELS_CMAP = mcolors.ListedColormap(['white', 'red', 'dodgerblue', 'gold',
-                                          'greenyellow', 'blueviolet'])
-
+try:
+    import matplotlib.pyplot as plt
+    import matplotlib.colors as mcolors
+    LABELS_CMAP = mcolors.ListedColormap(['white', 'red', 'dodgerblue', 'gold',
+                                              'greenyellow', 'blueviolet'])
+except ImportError:
+    pass
 from skimage.viewer.canvastools.base import CanvasToolBase
 
 
diff --git a/skimage/viewer/canvastools/recttool.py b/skimage/viewer/canvastools/recttool.py
index f055e439..929fe939 100644
--- a/skimage/viewer/canvastools/recttool.py
+++ b/skimage/viewer/canvastools/recttool.py
@@ -2,7 +2,6 @@ try:
     from matplotlib.widgets import RectangleSelector
 except ImportError:
     RectangleSelector = object
-    print("Could not import matplotlib -- skimage.viewer not available.")
 
 from skimage.viewer.canvastools.base import CanvasToolBase
 from skimage.viewer.canvastools.base import ToolHandles
diff --git a/skimage/viewer/plugins/color_histogram.py b/skimage/viewer/plugins/color_histogram.py
index dd54a93d..4826fc44 100644
--- a/skimage/viewer/plugins/color_histogram.py
+++ b/skimage/viewer/plugins/color_histogram.py
@@ -1,6 +1,8 @@
 import numpy as np
-import matplotlib.pyplot as plt
-
+try:
+    import matplotlib.pyplot as plt
+except ImportError:
+    pass
 from skimage import color
 from skimage import exposure
 from .plotplugin import PlotPlugin
diff --git a/skimage/viewer/plugins/overlayplugin.py b/skimage/viewer/plugins/overlayplugin.py
index 373d6bf4..7f016328 100644
--- a/skimage/viewer/plugins/overlayplugin.py
+++ b/skimage/viewer/plugins/overlayplugin.py
@@ -5,17 +5,12 @@ from .base import Plugin
 from ..utils import ClearColormap, update_axes_image
 
 import six
+from skimage._shared.version_requirements import is_installed
 
 
 __all__ = ['OverlayPlugin']
 
 
-def recent_mpl_version():
-    import matplotlib
-    version = matplotlib.__version__.split('.')
-    return int(version[0]) == 1 and int(version[1]) >= 2
-
-
 class OverlayPlugin(Plugin):
     """Plugin for ImageViewer that displays an overlay on top of main image.
 
@@ -38,14 +33,14 @@ class OverlayPlugin(Plugin):
               'cyan': (0, 1, 1)}
 
     def __init__(self, **kwargs):
-        if not recent_mpl_version():
+        if not is_installed('matplotlib', '>=1.2'):
             msg = "Matplotlib >= 1.2 required for OverlayPlugin."
             warn(RuntimeWarning(msg))
         super(OverlayPlugin, self).__init__(**kwargs)
         self._overlay_plot = None
         self._overlay = None
         self.cmap = None
-        self.color_names = list(self.colors.keys())
+        self.color_names = sorted(list(self.colors.keys()))
 
     def attach(self, image_viewer):
         super(OverlayPlugin, self).attach(image_viewer)
diff --git a/skimage/viewer/tests/test_plugins.py b/skimage/viewer/tests/test_plugins.py
index 7ef62730..497708a4 100644
--- a/skimage/viewer/tests/test_plugins.py
+++ b/skimage/viewer/tests/test_plugins.py
@@ -4,20 +4,14 @@ import skimage
 import skimage.data as data
 from skimage.filter.rank import median
 from skimage.morphology import disk
+from skimage.viewer import ImageViewer, viewer_available
 from numpy.testing import assert_equal, assert_allclose, assert_almost_equal
 from numpy.testing.decorators import skipif
-
-try:
-    from skimage.viewer.qt import qt_api
-    from skimage.viewer import ImageViewer
-    from skimage.viewer.plugins import (
-        LineProfile, Measure, CannyPlugin, LabelPainter, Crop, ColorHistogram,
-        PlotPlugin)
-    from skimage.viewer.plugins.base import Plugin
-    from skimage.viewer.widgets import Slider
-    viewer_available = not qt_api is None
-except ImportError:
-    viewer_available = False
+from skimage.viewer.plugins import (
+    LineProfile, Measure, CannyPlugin, LabelPainter, Crop, ColorHistogram,
+    PlotPlugin)
+from skimage.viewer.plugins.base import Plugin
+from skimage.viewer.widgets import Slider
 
 
 def setup_line_profile(image, limits='image'):
diff --git a/skimage/viewer/tests/test_tools.py b/skimage/viewer/tests/test_tools.py
index 9f02e762..6663c465 100644
--- a/skimage/viewer/tests/test_tools.py
+++ b/skimage/viewer/tests/test_tools.py
@@ -1,19 +1,15 @@
 from collections import namedtuple
 
 import numpy as np
-from skimage import data
 from numpy.testing import assert_equal
 from numpy.testing.decorators import skipif
-
-try:
-    from skimage.viewer.qt import qt_api
-    from skimage.viewer import ImageViewer
-    from skimage.viewer.canvastools import (
-        LineTool, ThickLineTool, RectangleTool, PaintTool)
-    from skimage.viewer.canvastools.base import CanvasToolBase
-    viewer_available = not qt_api is None
-except ImportError:
-    viewer_available = False
+from skimage import data
+from skimage.viewer import ImageViewer, viewer_available
+from skimage.viewer.canvastools import (
+    LineTool, ThickLineTool, RectangleTool, PaintTool)
+from skimage.viewer.canvastools.base import CanvasToolBase
+from numpy.testing import assert_equal
+from numpy.testing.decorators import skipif
 
 
 def get_end_points(image):
diff --git a/skimage/viewer/tests/test_utils.py b/skimage/viewer/tests/test_utils.py
index 30d74a51..3f9ec396 100644
--- a/skimage/viewer/tests/test_utils.py
+++ b/skimage/viewer/tests/test_utils.py
@@ -1,15 +1,14 @@
 # -*- coding: utf-8 -*-
+from skimage.viewer import viewer_available
+from skimage.viewer.qt import QtCore, QtGui
+from skimage.viewer import utils
+from skimage.viewer.utils import dialogs
 from numpy.testing.decorators import skipif
-
-try:
-    from skimage.viewer.qt import qt_api, QtCore, QtGui
-    from skimage.viewer import utils
-    from skimage.viewer.utils import dialogs
-except ImportError:
-    qt_api = None
+from skimage.viewer import utils
+from skimage.viewer.utils import dialogs
 
 
-@skipif(qt_api is None)
+@skipif(not viewer_available)
 def test_event_loop():
     utils.init_qtapp()
     timer = QtCore.QTimer()
@@ -17,7 +16,7 @@ def test_event_loop():
     utils.start_qtapp()
 
 
-@skipif(qt_api is None)
+@skipif(not viewer_available)
 def test_format_filename():
     fname = dialogs._format_filename(('apple', 2))
     assert fname == 'apple'
@@ -25,7 +24,7 @@ def test_format_filename():
     assert fname is None
 
 
-@skipif(qt_api is None)
+@skipif(not viewer_available)
 def test_open_file_dialog():
     utils.init_qtapp()
     timer = QtCore.QTimer()
@@ -34,7 +33,7 @@ def test_open_file_dialog():
     assert filename is None
 
 
-@skipif(qt_api is None)
+@skipif(not viewer_available)
 def test_save_file_dialog():
     utils.init_qtapp()
     timer = QtCore.QTimer()
diff --git a/skimage/viewer/tests/test_viewer.py b/skimage/viewer/tests/test_viewer.py
index cd6c7acb..1b93ff52 100644
--- a/skimage/viewer/tests/test_viewer.py
+++ b/skimage/viewer/tests/test_viewer.py
@@ -1,18 +1,13 @@
 
 from skimage import data
+from skimage.viewer.qt import QtGui, QtCore
+from skimage.viewer import ImageViewer, CollectionViewer, viewer_available
 from skimage.transform import pyramid_gaussian
+from skimage.viewer.plugins import OverlayPlugin
 from skimage.filter import sobel
 from numpy.testing import assert_equal
 from numpy.testing.decorators import skipif
-
-try:
-    from skimage.viewer.qt import qt_api, QtGui, QtCore
-    from skimage.viewer.plugins import OverlayPlugin
-    from skimage.viewer.plugins.overlayplugin import recent_mpl_version
-    from skimage.viewer import ImageViewer, CollectionViewer
-    viewer_available = not qt_api is None
-except ImportError:
-    viewer_available = False
+from skimage._shared.version_requirements import is_installed
 
 
 @skipif(not viewer_available)
@@ -58,7 +53,8 @@ def test_collection_viewer():
     view._format_coord(10, 10)
 
 
-@skipif(not viewer_available or not recent_mpl_version())
+@skipif(not viewer_available)
+@skipif(not is_installed('matplotlib', '>=1.2'))
 def test_viewer_with_overlay():
     img = data.coins()
     ov = OverlayPlugin(image_filter=sobel)
@@ -68,7 +64,7 @@ def test_viewer_with_overlay():
     import tempfile
     _, filename = tempfile.mkstemp(suffix='.png')
 
-    ov.color = 2
+    ov.color = 3
     assert_equal(ov.color, 'yellow')
     viewer.save_to_file(filename)
     ov.display_filtered_image(img)
@@ -79,5 +75,3 @@ def test_viewer_with_overlay():
     assert_equal(ov.overlay, img)
     assert_equal(ov.filtered_image, img)
 
-
-
diff --git a/skimage/viewer/tests/test_widgets.py b/skimage/viewer/tests/test_widgets.py
index aeb4ede2..ef3cb83c 100644
--- a/skimage/viewer/tests/test_widgets.py
+++ b/skimage/viewer/tests/test_widgets.py
@@ -1,19 +1,14 @@
 
 import os
 from skimage import data, img_as_float, io
+from skimage.viewer import ImageViewer, viewer_available
+from skimage.viewer.widgets import (
+    Slider, OKCancelButtons, SaveButtons, ComboBox, Text)
+from skimage.viewer.plugins.base import Plugin
+from skimage.viewer.qt import QtGui, QtCore
 from numpy.testing import assert_almost_equal, assert_equal
 from numpy.testing.decorators import skipif
 
-try:
-    from skimage.viewer.qt import qt_api, QtGui, QtCore
-    from skimage.viewer import ImageViewer
-    from skimage.viewer.widgets import (
-        Slider, OKCancelButtons, SaveButtons, ComboBox, Text)
-    from skimage.viewer.plugins.base import Plugin
-    viewer_available = not qt_api is None
-except ImportError:
-    viewer_available = False
-
 
 def get_image_viewer():
     image = data.coins()
diff --git a/skimage/viewer/utils/core.py b/skimage/viewer/utils/core.py
index 95176fcd..19a5c73d 100644
--- a/skimage/viewer/utils/core.py
+++ b/skimage/viewer/utils/core.py
@@ -9,18 +9,15 @@ try:
     from matplotlib.figure import Figure
     from matplotlib import _pylab_helpers
     from matplotlib.colors import LinearSegmentedColormap
-    if qt_api is None:
-        raise ImportError
-    else:
+    if not qt_api is None:
         from matplotlib.backends.backend_qt4 import FigureManagerQT
         from matplotlib.backends.backend_qt4agg import FigureCanvasQTAgg
-    if 'agg' not in mpl.get_backend().lower():
-        print("Recommended matplotlib backend is `Agg` for full "
-              "skimage.viewer functionality.")
+        if 'agg' not in mpl.get_backend().lower():
+            print("Recommended matplotlib backend is `Agg` for full "
+                  "skimage.viewer functionality.")
 except ImportError:
     FigureCanvasQTAgg = object  # hack to prevent nosetest and autodoc errors
     LinearSegmentedColormap = object
-    print("Could not import matplotlib -- skimage.viewer not available.")
 
 from ..qt import QtGui
 
diff --git a/skimage/viewer/viewers/core.py b/skimage/viewer/viewers/core.py
index 476017ef..52ac073a 100644
--- a/skimage/viewer/viewers/core.py
+++ b/skimage/viewer/viewers/core.py
@@ -123,7 +123,6 @@ class ImageViewer(QtGui.QMainWindow):
         self.fig, self.ax = utils.figimage(image)
         self.canvas = self.fig.canvas
         self.canvas.setParent(self)
-
         self.ax.autoscale(enable=False)
 
         self._image_plot = self.ax.images[0]
diff --git a/tools/build_versions.py b/tools/build_versions.py
index 2c0e32ba..5e33dbfa 100755
--- a/tools/build_versions.py
+++ b/tools/build_versions.py
@@ -4,9 +4,12 @@ from __future__ import print_function
 
 import numpy as np
 import scipy as sp
-import matplotlib as mpl
+from PIL import Image
 import six
 
-for m in (np, sp, mpl, six):
-    print(m.__name__.rjust(10), ' ', m.__version__)
-
+for m in (np, sp, Image, six):
+    if not m is None:
+        if m is Image:
+            print('PIL'.rjust(10), ' ', Image.VERSION)
+        else:
+            print(m.__name__.rjust(10), ' ', m.__version__)