Error when testing SciPy

Question

When testing scipy using the nose package using scipy.test(), the test fails under Ubuntu 12.04 with all the vanilla packages installed. Do I have to worry, and

Answer 1

If you take a look inside /usr/lib/python2.7/dist-packages/scipy/ndimage/tests/test_io.py you should see:

def test_imread():
    lp = os.path.join(os.path.dirname(__file__), 'dots.png')
    img = ndi.imread(lp)
    assert_array_equal(img.shape, (300, 420, 3))

    img = ndi.imread(lp, flatten=True)
    assert_array_equal(img.shape, (300, 420))

This test seems to be testing if flatten=True converts an RGB image into a 1-bit greyscale image.

On my Ubuntu 11.10 system, however, dots.png is already a 1-bit image file:

% file /usr/share/pyshared/scipy/ndimage/tests/dots.png
/usr/share/pyshared/scipy/ndimage/tests/dots.png: PNG image data, 420 x 300, 1-bit colormap, non-interlaced

If I perform the test (manually) on a RGBA image, then the test works:

In [18]: z = ndi.imread('image.png')

In [20]: z.shape
Out[20]: (250, 250, 4)

In [24]: w = ndi.imread('image.png', flatten = True)

In [25]: w.shape
Out[25]: (250, 250)

So I don't think there is anything seriously wrong here, just that perhaps the dots.png file that was shipped should have been an RGB image instead of a greyscale one.