/usr/lib/python3/dist-packages/matplotlib/tests/test_compare_images.py is in python3-matplotlib 1.5.1-1ubuntu1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 | from __future__ import (absolute_import, division, print_function,
unicode_literals)
from matplotlib.externals import six
import os
import shutil
from nose.tools import assert_equal, assert_not_equal, assert_almost_equal
from matplotlib.testing.compare import compare_images
from matplotlib.testing.decorators import _image_directories
baseline_dir, result_dir = _image_directories(lambda: 'dummy func')
# Tests of the image comparison algorithm.
def image_comparison_expect_rms(im1, im2, tol, expect_rms):
"""Compare two images, expecting a particular RMS error.
im1 and im2 are filenames relative to the baseline_dir directory.
tol is the tolerance to pass to compare_images.
expect_rms is the expected RMS value, or None. If None, the test will
succeed if compare_images succeeds. Otherwise, the test will succeed if
compare_images fails and returns an RMS error almost equal to this value.
"""
im1 = os.path.join(baseline_dir, im1)
im2_src = os.path.join(baseline_dir, im2)
im2 = os.path.join(result_dir, im2)
# Move im2 from baseline_dir to result_dir. This will ensure that
# compare_images writes the diff file to result_dir, instead of trying to
# write to the (possibly read-only) baseline_dir.
shutil.copyfile(im2_src, im2)
results = compare_images(im1, im2, tol=tol, in_decorator=True)
if expect_rms is None:
assert_equal(None, results)
else:
assert_not_equal(None, results)
assert_almost_equal(expect_rms, results['rms'], places=4)
def test_image_compare_basic():
#: Test comparison of an image and the same image with minor differences.
# This expects the images to compare equal under normal tolerance, and have
# a small RMS.
im1 = 'basn3p02.png'
im2 = 'basn3p02-minorchange.png'
image_comparison_expect_rms(im1, im2, tol=10, expect_rms=None)
# Now test with no tolerance.
image_comparison_expect_rms(im1, im2, tol=0, expect_rms=6.50646)
def test_image_compare_1px_offset():
#: Test comparison with an image that is shifted by 1px in the X axis.
im1 = 'basn3p02.png'
im2 = 'basn3p02-1px-offset.png'
image_comparison_expect_rms(im1, im2, tol=0, expect_rms=90.15611)
def test_image_compare_half_1px_offset():
#: Test comparison with an image with half the pixels shifted by 1px in
#: the X axis.
im1 = 'basn3p02.png'
im2 = 'basn3p02-half-1px-offset.png'
image_comparison_expect_rms(im1, im2, tol=0, expect_rms=63.75)
def test_image_compare_scrambled():
#: Test comparison of an image and the same image scrambled.
# This expects the images to compare completely different, with a very
# large RMS.
# Note: The image has been scrambled in a specific way, by having each
# color component of each pixel randomly placed somewhere in the image. It
# contains exactly the same number of pixels of each color value of R, G
# and B, but in a totally different position.
im1 = 'basn3p02.png'
im2 = 'basn3p02-scrambled.png'
# Test with no tolerance to make sure that we pick up even a very small RMS
# error.
image_comparison_expect_rms(im1, im2, tol=0, expect_rms=172.63582)
def test_image_compare_shade_difference():
#: Test comparison of an image and a slightly brighter image.
# The two images are solid color, with the second image being exactly 1
# color value brighter.
# This expects the images to compare equal under normal tolerance, and have
# an RMS of exactly 1.
im1 = 'all127.png'
im2 = 'all128.png'
image_comparison_expect_rms(im1, im2, tol=0, expect_rms=1.0)
# Now test the reverse comparison.
image_comparison_expect_rms(im2, im1, tol=0, expect_rms=1.0)
if __name__ == '__main__':
import nose
nose.runmodule(argv=['-s', '--with-doctest'], exit=False)
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