python3-matplotlib 2.0.0+dfsg1-2 / usr / lib / python3 / dist-packages / matplotlib / tests / test_image.py

from __future__ import (absolute_import, division, print_function,
                        unicode_literals)

import six
import io
import os
import warnings

from nose.plugins.attrib import attr

import numpy as np

from matplotlib.testing.decorators import (image_comparison,
                                           knownfailureif, cleanup)
from matplotlib.image import (BboxImage, imread, NonUniformImage,
                              AxesImage, FigureImage, PcolorImage)
from matplotlib.transforms import Bbox, Affine2D, TransformedBbox
from matplotlib import rcParams, rc_context
from matplotlib import patches
import matplotlib.pyplot as plt

from matplotlib import mlab
from nose.tools import assert_raises
from numpy.testing import (
    assert_array_equal, assert_array_almost_equal, assert_allclose)
from matplotlib.testing.noseclasses import KnownFailureTest
from copy import copy
from numpy import ma
import matplotlib.colors as colors
import matplotlib.pyplot as plt
import matplotlib.mlab as mlab
import numpy as np

import nose

try:
    from PIL import Image
    HAS_PIL = True
except ImportError:
    HAS_PIL = False


@image_comparison(baseline_images=['image_interps'])
def test_image_interps():
    'make the basic nearest, bilinear and bicubic interps'
    X = np.arange(100)
    X = X.reshape(5, 20)

    fig = plt.figure()
    ax1 = fig.add_subplot(311)
    ax1.imshow(X, interpolation='nearest')
    ax1.set_title('three interpolations')
    ax1.set_ylabel('nearest')

    ax2 = fig.add_subplot(312)
    ax2.imshow(X, interpolation='bilinear')
    ax2.set_ylabel('bilinear')

    ax3 = fig.add_subplot(313)
    ax3.imshow(X, interpolation='bicubic')
    ax3.set_ylabel('bicubic')

@image_comparison(baseline_images=['interp_nearest_vs_none'],
                  extensions=['pdf', 'svg'], remove_text=True)
def test_interp_nearest_vs_none():
    'Test the effect of "nearest" and "none" interpolation'
    # Setting dpi to something really small makes the difference very
    # visible. This works fine with pdf, since the dpi setting doesn't
    # affect anything but images, but the agg output becomes unusably
    # small.
    rcParams['savefig.dpi'] = 3
    X = np.array([[[218, 165, 32], [122, 103, 238]],
                  [[127, 255, 0], [255, 99, 71]]], dtype=np.uint8)
    fig = plt.figure()
    ax1 = fig.add_subplot(121)
    ax1.imshow(X, interpolation='none')
    ax1.set_title('interpolation none')
    ax2 = fig.add_subplot(122)
    ax2.imshow(X, interpolation='nearest')
    ax2.set_title('interpolation nearest')


@image_comparison(baseline_images=['figimage-0', 'figimage-1'], extensions=['png'])
def test_figimage():
    'test the figimage method'

    for suppressComposite in False, True:
        fig = plt.figure(figsize=(2,2), dpi=100)
        fig.suppressComposite = suppressComposite
        x,y = np.ix_(np.arange(100.0)/100.0, np.arange(100.0)/100.0)
        z = np.sin(x**2 + y**2 - x*y)
        c = np.sin(20*x**2 + 50*y**2)
        img = z + c/5

        fig.figimage(img, xo=0, yo=0, origin='lower')
        fig.figimage(img[::-1,:], xo=0, yo=100, origin='lower')
        fig.figimage(img[:,::-1], xo=100, yo=0, origin='lower')
        fig.figimage(img[::-1,::-1], xo=100, yo=100, origin='lower')

@cleanup
def test_image_python_io():
    fig = plt.figure()
    ax = fig.add_subplot(111)
    ax.plot([1,2,3])
    buffer = io.BytesIO()
    fig.savefig(buffer)
    buffer.seek(0)
    plt.imread(buffer)


@knownfailureif(not HAS_PIL)
def test_imread_pil_uint16():
    img = plt.imread(os.path.join(os.path.dirname(__file__),
                     'baseline_images', 'test_image', 'uint16.tif'))
    assert (img.dtype == np.uint16)
    assert np.sum(img) == 134184960

# def test_image_unicode_io():
#     fig = plt.figure()
#     ax = fig.add_subplot(111)
#     ax.plot([1,2,3])
#     fname = u"\u0a3a\u0a3a.png"
#     fig.savefig(fname)
#     plt.imread(fname)
#     os.remove(fname)


@cleanup
def test_imsave():
    # The goal here is that the user can specify an output logical DPI
    # for the image, but this will not actually add any extra pixels
    # to the image, it will merely be used for metadata purposes.

    # So we do the traditional case (dpi == 1), and the new case (dpi
    # == 100) and read the resulting PNG files back in and make sure
    # the data is 100% identical.
    from numpy import random
    random.seed(1)
    data = random.rand(256, 128)

    buff_dpi1 = io.BytesIO()
    plt.imsave(buff_dpi1, data, dpi=1)

    buff_dpi100 = io.BytesIO()
    plt.imsave(buff_dpi100, data, dpi=100)

    buff_dpi1.seek(0)
    arr_dpi1 = plt.imread(buff_dpi1)

    buff_dpi100.seek(0)
    arr_dpi100 = plt.imread(buff_dpi100)

    assert arr_dpi1.shape == (256, 128, 4)
    assert arr_dpi100.shape == (256, 128, 4)

    assert_array_equal(arr_dpi1, arr_dpi100)

def test_imsave_color_alpha():
    # Test that imsave accept arrays with ndim=3 where the third dimension is
    # color and alpha without raising any exceptions, and that the data is
    # acceptably preserved through a save/read roundtrip.
    from numpy import random
    random.seed(1)
    data = random.rand(16, 16, 4)

    buff = io.BytesIO()
    plt.imsave(buff, data)

    buff.seek(0)
    arr_buf = plt.imread(buff)

    # Recreate the float -> uint8 conversion of the data
    # We can only expect to be the same with 8 bits of precision,
    # since that's what the PNG file used.
    data = (255*data).astype('uint8')
    arr_buf = (255*arr_buf).astype('uint8')

    assert_array_equal(data, arr_buf)

@image_comparison(baseline_images=['image_alpha'], remove_text=True)
def test_image_alpha():
    plt.figure()

    np.random.seed(0)
    Z = np.random.rand(6, 6)

    plt.subplot(131)
    plt.imshow(Z, alpha=1.0, interpolation='none')

    plt.subplot(132)
    plt.imshow(Z, alpha=0.5, interpolation='none')

    plt.subplot(133)
    plt.imshow(Z, alpha=0.5, interpolation='nearest')

@cleanup
def test_cursor_data():
    from matplotlib.backend_bases import MouseEvent

    fig, ax = plt.subplots()
    im = ax.imshow(np.arange(100).reshape(10, 10), origin='upper')

    x, y = 4, 4
    xdisp, ydisp = ax.transData.transform_point([x, y])

    event = MouseEvent('motion_notify_event', fig.canvas, xdisp, ydisp)
    z = im.get_cursor_data(event)
    assert z == 44, "Did not get 44, got %d" % z

    # Now try for a point outside the image
    # Tests issue #4957
    x, y = 10.1, 4
    xdisp, ydisp = ax.transData.transform_point([x, y])

    event = MouseEvent('motion_notify_event', fig.canvas, xdisp, ydisp)
    z = im.get_cursor_data(event)
    assert z is None, "Did not get None, got %d" % z

    # Hmm, something is wrong here... I get 0, not None...
    # But, this works further down in the tests with extents flipped
    #x, y = 0.1, -0.1
    #xdisp, ydisp = ax.transData.transform_point([x, y])
    #event = MouseEvent('motion_notify_event', fig.canvas, xdisp, ydisp)
    #z = im.get_cursor_data(event)
    #assert z is None, "Did not get None, got %d" % z

    ax.clear()
    # Now try with the extents flipped.
    im = ax.imshow(np.arange(100).reshape(10, 10), origin='lower')

    x, y = 4, 4
    xdisp, ydisp = ax.transData.transform_point([x, y])

    event = MouseEvent('motion_notify_event', fig.canvas, xdisp, ydisp)
    z = im.get_cursor_data(event)
    assert z == 44, "Did not get 44, got %d" % z

    fig, ax = plt.subplots()
    im = ax.imshow(np.arange(100).reshape(10, 10), extent=[0, 0.5, 0, 0.5])

    x, y = 0.25, 0.25
    xdisp, ydisp = ax.transData.transform_point([x, y])

    event = MouseEvent('motion_notify_event', fig.canvas, xdisp, ydisp)
    z = im.get_cursor_data(event)
    assert z == 55, "Did not get 55, got %d" % z

    # Now try for a point outside the image
    # Tests issue #4957
    x, y = 0.75, 0.25
    xdisp, ydisp = ax.transData.transform_point([x, y])

    event = MouseEvent('motion_notify_event', fig.canvas, xdisp, ydisp)
    z = im.get_cursor_data(event)
    assert z is None, "Did not get None, got %d" % z

    x, y = 0.01, -0.01
    xdisp, ydisp = ax.transData.transform_point([x, y])

    event = MouseEvent('motion_notify_event', fig.canvas, xdisp, ydisp)
    z = im.get_cursor_data(event)
    assert z is None, "Did not get None, got %d" % z


@image_comparison(baseline_images=['image_clip'])
def test_image_clip():
    d = [[1, 2], [3, 4]]

    fig, ax = plt.subplots()
    im = ax.imshow(d)
    patch = patches.Circle((0, 0), radius=1, transform=ax.transData)
    im.set_clip_path(patch)


@image_comparison(baseline_images=['image_cliprect'])
def test_image_cliprect():
    import matplotlib.patches as patches

    fig = plt.figure()
    ax = fig.add_subplot(111)
    d = [[1,2],[3,4]]

    im = ax.imshow(d, extent=(0,5,0,5))

    rect = patches.Rectangle(xy=(1,1), width=2, height=2, transform=im.axes.transData)
    im.set_clip_path(rect)

@image_comparison(baseline_images=['imshow'], remove_text=True)
def test_imshow():
    import numpy as np
    import matplotlib.pyplot as plt

    fig = plt.figure()
    arr = np.arange(100).reshape((10, 10))
    ax = fig.add_subplot(111)
    ax.imshow(arr, interpolation="bilinear", extent=(1,2,1,2))
    ax.set_xlim(0,3)
    ax.set_ylim(0,3)

@image_comparison(baseline_images=['no_interpolation_origin'], remove_text=True)
def test_no_interpolation_origin():
    fig = plt.figure()
    ax = fig.add_subplot(211)
    ax.imshow(np.arange(100).reshape((2, 50)), origin="lower", interpolation='none')

    ax = fig.add_subplot(212)
    ax.imshow(np.arange(100).reshape((2, 50)), interpolation='none')

@image_comparison(baseline_images=['image_shift'], remove_text=True,
                  extensions=['pdf', 'svg'])
def test_image_shift():
    from matplotlib.colors import LogNorm

    imgData = [[1.0/(x) + 1.0/(y) for x in range(1,100)] for y in range(1,100)]
    tMin=734717.945208
    tMax=734717.946366

    fig = plt.figure()
    ax = fig.add_subplot(111)
    ax.imshow(imgData, norm=LogNorm(), interpolation='none',
              extent=(tMin, tMax, 1, 100))
    ax.set_aspect('auto')

@cleanup
def test_image_edges():
    f = plt.figure(figsize=[1, 1])
    ax = f.add_axes([0, 0, 1, 1], frameon=False)

    data = np.tile(np.arange(12), 15).reshape(20, 9)

    im = ax.imshow(data, origin='upper',
                   extent=[-10, 10, -10, 10], interpolation='none',
                   cmap='gray'
                   )

    x = y = 2
    ax.set_xlim([-x, x])
    ax.set_ylim([-y, y])

    ax.set_xticks([])
    ax.set_yticks([])

    buf = io.BytesIO()
    f.savefig(buf, facecolor=(0, 1, 0))

    buf.seek(0)

    im = plt.imread(buf)
    r, g, b, a = sum(im[:, 0])
    r, g, b, a = sum(im[:, -1])

    assert g != 100, 'Expected a non-green edge - but sadly, it was.'

@image_comparison(baseline_images=['image_composite_background'], remove_text=True)
def test_image_composite_background():
    fig = plt.figure()
    ax = fig.add_subplot(111)
    arr = np.arange(12).reshape(4, 3)
    ax.imshow(arr, extent=[0, 2, 15, 0])
    ax.imshow(arr, extent=[4, 6, 15, 0])
    ax.set_facecolor((1, 0, 0, 0.5))
    ax.set_xlim([0, 12])

@image_comparison(baseline_images=['image_composite_alpha'], remove_text=True)
def test_image_composite_alpha():
    """
    Tests that the alpha value is recognized and correctly applied in the
    process of compositing images together.
    """
    fig = plt.figure()
    ax = fig.add_subplot(111)
    arr = np.zeros((11, 21, 4))
    arr[:, :, 0] = 1
    arr[:, :, 3] = np.concatenate((np.arange(0, 1.1, 0.1), np.arange(0, 1, 0.1)[::-1]))
    arr2 = np.zeros((21, 11, 4))
    arr2[:, :, 0] = 1
    arr2[:, :, 1] = 1
    arr2[:, :, 3] = np.concatenate((np.arange(0, 1.1, 0.1), np.arange(0, 1, 0.1)[::-1]))[:, np.newaxis]
    ax.imshow(arr, extent=[1, 2, 5, 0], alpha=0.3)
    ax.imshow(arr, extent=[2, 3, 5, 0], alpha=0.6)
    ax.imshow(arr, extent=[3, 4, 5, 0])
    ax.imshow(arr2, extent=[0, 5, 1, 2])
    ax.imshow(arr2, extent=[0, 5, 2, 3], alpha=0.6)
    ax.imshow(arr2, extent=[0, 5, 3, 4], alpha=0.3)
    ax.set_facecolor((0, 0.5, 0, 1))
    ax.set_xlim([0, 5])
    ax.set_ylim([5, 0])


@image_comparison(baseline_images=['rasterize_10dpi'], extensions=['pdf','svg'], remove_text=True)
def test_rasterize_dpi():
    # This test should check rasterized rendering with high output resolution.
    # It plots a rasterized line and a normal image with implot. So it will catch
    # when images end up in the wrong place in case of non-standard dpi setting.
    # Instead of high-res rasterization i use low-res.  Therefore the fact that the
    # resolution is non-standard is is easily checked by image_comparison.
    import numpy as np
    import matplotlib.pyplot as plt

    img = np.asarray([[1, 2], [3, 4]])

    fig, axes = plt.subplots(1, 3, figsize = (3, 1))

    axes[0].imshow(img)

    axes[1].plot([0,1],[0,1], linewidth=20., rasterized=True)
    axes[1].set(xlim = (0,1), ylim = (-1, 2))

    axes[2].plot([0,1],[0,1], linewidth=20.)
    axes[2].set(xlim = (0,1), ylim = (-1, 2))

    # Low-dpi PDF rasterization errors prevent proper image comparison tests.
    # Hide detailed structures like the axes spines.
    for ax in axes:
        ax.set_xticks([])
        ax.set_yticks([])
        for spine in ax.spines.values():
            spine.set_visible(False)

    rcParams['savefig.dpi'] = 10


@image_comparison(baseline_images=['bbox_image_inverted'], remove_text=True)
def test_bbox_image_inverted():
    # This is just used to produce an image to feed to BboxImage
    image = np.arange(100).reshape((10, 10))

    ax = plt.subplot(111)
    bbox_im = BboxImage(
        TransformedBbox(Bbox([[100, 100], [0, 0]]), ax.transData))
    bbox_im.set_data(image)
    bbox_im.set_clip_on(False)
    ax.set_xlim(0, 100)
    ax.set_ylim(0, 100)
    ax.add_artist(bbox_im)

    image = np.identity(10)

    bbox_im = BboxImage(
        TransformedBbox(Bbox([[0.1, 0.2], [0.3, 0.25]]), ax.figure.transFigure))
    bbox_im.set_data(image)
    bbox_im.set_clip_on(False)
    ax.add_artist(bbox_im)


@cleanup
def test_get_window_extent_for_AxisImage():
    # Create a figure of known size (1000x1000 pixels), place an image
    # object at a given location and check that get_window_extent()
    # returns the correct bounding box values (in pixels).

    im = np.array([[0.25, 0.75, 1.0, 0.75], [0.1, 0.65, 0.5, 0.4], \
        [0.6, 0.3, 0.0, 0.2], [0.7, 0.9, 0.4, 0.6]])
    fig = plt.figure(figsize=(10, 10), dpi=100)
    ax = plt.subplot()
    ax.set_position([0, 0, 1, 1])
    ax.set_xlim(0, 1)
    ax.set_ylim(0, 1)
    im_obj = ax.imshow(im, extent=[0.4, 0.7, 0.2, 0.9], interpolation='nearest')

    fig.canvas.draw()
    renderer = fig.canvas.renderer
    im_bbox = im_obj.get_window_extent(renderer)

    assert_array_equal(im_bbox.get_points(), [[400, 200], [700, 900]])


@image_comparison(baseline_images=['zoom_and_clip_upper_origin'],
                  remove_text=True,
                  extensions=['png'])
def test_zoom_and_clip_upper_origin():
    image = np.arange(100)
    image = image.reshape((10, 10))

    fig = plt.figure()
    ax = fig.add_subplot(111)
    ax.imshow(image)
    ax.set_ylim(2.0, -0.5)
    ax.set_xlim(-0.5, 2.0)


@cleanup
def test_nonuniformimage_setcmap():
    ax = plt.gca()
    im = NonUniformImage(ax)
    im.set_cmap('Blues')


@cleanup
def test_nonuniformimage_setnorm():
    ax = plt.gca()
    im = NonUniformImage(ax)
    im.set_norm(plt.Normalize())


@knownfailureif(not HAS_PIL)
@cleanup
def test_jpeg_alpha():
    plt.figure(figsize=(1, 1), dpi=300)
    # Create an image that is all black, with a gradient from 0-1 in
    # the alpha channel from left to right.
    im = np.zeros((300, 300, 4), dtype=float)
    im[..., 3] = np.linspace(0.0, 1.0, 300)

    plt.figimage(im)

    buff = io.BytesIO()
    with rc_context({'savefig.facecolor': 'red'}):
        plt.savefig(buff, transparent=True, format='jpg', dpi=300)

    buff.seek(0)
    image = Image.open(buff)

    # If this fails, there will be only one color (all black). If this
    # is working, we should have all 256 shades of grey represented.
    num_colors = len(image.getcolors(256))
    assert 175 <= num_colors <= 185, 'num colors: %d' % (num_colors, )
    # The fully transparent part should be red, not white or black
    # or anything else
    corner_pixel = image.getpixel((0, 0))
    assert corner_pixel == (254, 0, 0), "corner pixel: %r" % (corner_pixel, )


@cleanup
def test_nonuniformimage_setdata():
    ax = plt.gca()
    im = NonUniformImage(ax)
    x = np.arange(3, dtype=np.float64)
    y = np.arange(4, dtype=np.float64)
    z = np.arange(12, dtype=np.float64).reshape((4, 3))
    im.set_data(x, y, z)
    x[0] = y[0] = z[0, 0] = 9.9
    assert im._A[0, 0] == im._Ax[0] == im._Ay[0] == 0, 'value changed'


@cleanup
def test_axesimage_setdata():
    ax = plt.gca()
    im = AxesImage(ax)
    z = np.arange(12, dtype=np.float64).reshape((4, 3))
    im.set_data(z)
    z[0, 0] = 9.9
    assert im._A[0, 0] == 0, 'value changed'


@cleanup
def test_figureimage_setdata():
    fig = plt.gcf()
    im = FigureImage(fig)
    z = np.arange(12, dtype=np.float64).reshape((4, 3))
    im.set_data(z)
    z[0, 0] = 9.9
    assert im._A[0, 0] == 0, 'value changed'


@cleanup
def test_pcolorimage_setdata():
    ax = plt.gca()
    im = PcolorImage(ax)
    x = np.arange(3, dtype=np.float64)
    y = np.arange(4, dtype=np.float64)
    z = np.arange(6, dtype=np.float64).reshape((3, 2))
    im.set_data(x, y, z)
    x[0] = y[0] = z[0, 0] = 9.9
    assert im._A[0, 0] == im._Ax[0] == im._Ay[0] == 0, 'value changed'


@cleanup
def test_minimized_rasterized():
    # This ensures that the rasterized content in the colorbars is
    # only as thick as the colorbar, and doesn't extend to other parts
    # of the image.  See #5814.  While the original bug exists only
    # in Postscript, the best way to detect it is to generate SVG
    # and then parse the output to make sure the two colorbar images
    # are the same size.
    from xml.etree import ElementTree

    np.random.seed(0)
    data = np.random.rand(10, 10)

    fig, ax = plt.subplots(1, 2)
    p1 = ax[0].pcolormesh(data)
    p2 = ax[1].pcolormesh(data)

    plt.colorbar(p1, ax=ax[0])
    plt.colorbar(p2, ax=ax[1])

    buff = io.BytesIO()
    plt.savefig(buff, format='svg')

    buff = io.BytesIO(buff.getvalue())
    tree = ElementTree.parse(buff)
    width = None
    for image in tree.iter('image'):
        if width is None:
            width = image['width']
        else:
            if image['width'] != width:
                assert False


@attr('network')
def test_load_from_url():
    req = six.moves.urllib.request.urlopen(
        "http://matplotlib.org/_static/logo_sidebar_horiz.png")
    Z = plt.imread(req)


@image_comparison(baseline_images=['log_scale_image'],
                  remove_text=True)
def test_log_scale_image():
    Z = np.zeros((10, 10))
    Z[::2] = 1

    fig = plt.figure()
    ax = fig.add_subplot(111)

    ax.imshow(Z, extent=[1, 100, 1, 100], cmap='viridis',
              vmax=1, vmin=-1)
    ax.set_yscale('log')



@image_comparison(baseline_images=['rotate_image'],
                  remove_text=True)
def test_rotate_image():
    delta = 0.25
    x = y = np.arange(-3.0, 3.0, delta)
    X, Y = np.meshgrid(x, y)
    Z1 = mlab.bivariate_normal(X, Y, 1.0, 1.0, 0.0, 0.0)
    Z2 = mlab.bivariate_normal(X, Y, 1.5, 0.5, 1, 1)
    Z = Z2 - Z1  # difference of Gaussians

    fig, ax1 = plt.subplots(1, 1)
    im1 = ax1.imshow(Z, interpolation='none', cmap='viridis',
                     origin='lower',
                     extent=[-2, 4, -3, 2], clip_on=True)

    trans_data2 = Affine2D().rotate_deg(30) + ax1.transData
    im1.set_transform(trans_data2)

    # display intended extent of the image
    x1, x2, y1, y2 = im1.get_extent()

    ax1.plot([x1, x2, x2, x1, x1], [y1, y1, y2, y2, y1], "r--", lw=3,
             transform=trans_data2)

    ax1.set_xlim(2, 5)
    ax1.set_ylim(0, 4)


@cleanup
def test_image_preserve_size():
    buff = io.BytesIO()

    im = np.zeros((481, 321))
    plt.imsave(buff, im)

    buff.seek(0)
    img = plt.imread(buff)

    assert img.shape[:2] == im.shape


@cleanup
def test_image_preserve_size2():
    n = 7
    data = np.identity(n, float)

    fig = plt.figure(figsize=(n, n), frameon=False)

    ax = plt.Axes(fig, [0.0, 0.0, 1.0, 1.0])
    ax.set_axis_off()
    fig.add_axes(ax)
    ax.imshow(data, interpolation='nearest', origin='lower',aspect='auto')
    buff = io.BytesIO()
    fig.savefig(buff, dpi=1)

    buff.seek(0)
    img = plt.imread(buff)

    assert img.shape == (7, 7, 4)

    assert_array_equal(np.asarray(img[:, :, 0], bool),
                       np.identity(n, bool)[::-1])


@image_comparison(baseline_images=['mask_image_over_under'],
                  remove_text=True, extensions=['png'])
def test_mask_image_over_under():
    delta = 0.025
    x = y = np.arange(-3.0, 3.0, delta)
    X, Y = np.meshgrid(x, y)
    Z1 = mlab.bivariate_normal(X, Y, 1.0, 1.0, 0.0, 0.0)
    Z2 = mlab.bivariate_normal(X, Y, 1.5, 0.5, 1, 1)
    Z = 10*(Z2 - Z1)  # difference of Gaussians

    palette = copy(plt.cm.gray)
    palette.set_over('r', 1.0)
    palette.set_under('g', 1.0)
    palette.set_bad('b', 1.0)
    Zm = ma.masked_where(Z > 1.2, Z)
    fig, (ax1, ax2) = plt.subplots(1, 2)
    im = ax1.imshow(Zm, interpolation='bilinear',
                    cmap=palette,
                    norm=colors.Normalize(vmin=-1.0, vmax=1.0, clip=False),
                    origin='lower', extent=[-3, 3, -3, 3])
    ax1.set_title('Green=low, Red=high, Blue=bad')
    fig.colorbar(im, extend='both', orientation='horizontal',
                 ax=ax1, aspect=10)

    im = ax2.imshow(Zm, interpolation='nearest',
                    cmap=palette,
                    norm=colors.BoundaryNorm([-1, -0.5, -0.2, 0, 0.2, 0.5, 1],
                                             ncolors=256, clip=False),
                    origin='lower', extent=[-3, 3, -3, 3])
    ax2.set_title('With BoundaryNorm')
    fig.colorbar(im, extend='both', spacing='proportional',
                 orientation='horizontal', ax=ax2, aspect=10)


@image_comparison(baseline_images=['mask_image'],
                  remove_text=True)
def test_mask_image():
    # Test mask image two ways: Using nans and using a masked array.

    fig, (ax1, ax2) = plt.subplots(1, 2)

    A = np.ones((5, 5))
    A[1:2, 1:2] = np.nan

    ax1.imshow(A, interpolation='nearest')

    A = np.zeros((5, 5), dtype=np.bool)
    A[1:2, 1:2] = True
    A = np.ma.masked_array(np.ones((5, 5), dtype=np.uint16), A)

    ax2.imshow(A, interpolation='nearest')


@image_comparison(baseline_images=['imshow_endianess'],
                  remove_text=True, extensions=['png'])
def test_imshow_endianess():
    x = np.arange(10)
    X, Y = np.meshgrid(x, x)
    Z = ((X-5)**2 + (Y-5)**2)**0.5

    fig, (ax1, ax2) = plt.subplots(1, 2)

    kwargs = dict(origin="lower", interpolation='nearest',
                  cmap='viridis')

    ax1.imshow(Z.astype('<f8'), **kwargs)
    ax2.imshow(Z.astype('>f8'), **kwargs)


@cleanup
def test_imshow_no_warn_invalid():
    with warnings.catch_warnings(record=True) as warns:
        warnings.simplefilter("always")
        plt.imshow([[1, 2], [3, np.nan]])
    assert len(warns) == 0


if __name__ == '__main__':
    nose.runmodule(argv=['-s', '--with-doctest'], exit=False)