[Numpy-discussion] PIL and NumPy

[Chris Barker - NOAA Federal]

On Jul 12, 2013, at 8:51 PM, Brady McCary <brady.mccary at gmail.com> wrote:

>
> something to do with an alpha channel being present.

I'd check and see how PIL is storing the alpha channel. If it's RGBA,
then I'd expect it to work.

But I'd PIL is storing the alpha channel as a separate band, then I'm
not surprised you have an issue.

Can you either drop the alpha or convert to RGBA?

There is also a package called something line "imageArray" that loads
and saves image formats directly to/from numpy arrays-maybe that would
be helpful.

CHB


> When I remove the
> alpha channel, things appear to work as I expect. Any discussion on
> the matter?
>
> Brady
>
> On Fri, Jul 12, 2013 at 10:00 PM, Brady McCary <brady.mccary at gmail.com> wrote:
>> NumPy Folks,
>>
>> I want to load images with PIL and then operate on them with NumPy.
>> According to the PIL and NumPy documentation, I would expect the
>> following to work, but it is not.
>>
>>
>>
>> Python 2.7.4 (default, Apr 19 2013, 18:28:01)
>> [GCC 4.7.3] on linux2
>> Type "help", "copyright", "credits" or "license" for more information.
>>>>> import numpy
>>>>> numpy.version.version
>>>>>
>>>>> import Image
>>>>> Image.VERSION
>> '1.1.7'
>>>>>
>>>>> im = Image.open('big-0.png')
>>>>> im.size
>> (2550, 3300)
>>>>>
>>>>> ar = numpy.asarray(im)
>>>>> ar.size
>> 1
>>>>> ar.shape
>> ()
>>>>> ar
>> array(<PIL.PngImagePlugin.PngImageFile image mode=LA size=2550x3300 at
>> 0x1E5BA70>, dtype=object)
>>
>>
>>
>> By "not working" I mean that I would have expected the data to be
>> loaded/available in ar. PIL and NumPy/SciPy seem to be working fine
>> independently of each other. Any guidance?
>>
>> Brady
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