[Numpy-discussion] Question about slicing

[Pauli Virtanen]

Sat, 16 May 2009 22:05:16 +0000, Jorge Scandaliaris wrote:
[clip]
> I downloaded the scipy logo:
> http://docs.scipy.org/doc/_static/scipyshiny_small.png and did the
> following:
> 
> img = Image.open('./scipyshiny_small.png')
> 
> mpl.pylab.imshow(img)  # Comes upside down
> aimg = asarray(img)
> mpl.pylab.imshow(aimg) # Comes OK

Ah, that was it. Apparently, matplotlib imshow uses a different 
conversion mechanism if the input is a Image.Image from PIL, than if it 
is an array. There's a dedicated function matplotlib.image.pil_to_array 
which seems to work differently from asarray.

This may actually be a bug in matplotlib; perhaps you should ask the 
people on the matplotlib lists if this is really the intended behavior.

-- 
Pauli Virtanen