Harald:

I know this is an old question but my feeling was in wasn't really
answered properly,
possibly because I inadvertantly took it off track with a response
which had an aside on
SAGE searching.

Since PIL has come up a few times on SAGE lists in vague ways, I
thought I'd try to
be more detailed. Here is a way using SAGE which might help. First,
it requires some preparation.

I'll assume you have installed sage in SAGEROOT (an absolute
pathname). (I'm going
to go into more detail that I know you need Harald since I hope to help others
who might know less about SAGE too).

You must install PIL from http://www.pythonware.com/products/pil/. Here's how:

(a) download the tarball from a link on the URL mentioned above, say
http://effbot.org/downloads/Imaging-1.1.6.tar.gz;
(b) extract it to SAGEROOT/local/lib/python/site-packages
(c) cd SAGEROOT/local/lib/python2.5/site-packages/Imaging-1.1.6
(d) run  ../../../../bin/python setup.py install
(e) install ImageMagick (unless you have xv installed, which you
probably don't);
in ubuntu, it's
sudo apt-get install imagemagick (or sudo apt-cache search
imagemagick, and install
a bunch of related packages too);
(f) in sage, type
sage: from PIL import Image
sage: im = Image.open("PATH/mypic.jpg")
sage: im.show(command="display")

Of course, im.[TAB] gives you more commands to play with and the online tutorial
http://www.pythonware.com/library/pil/handbook/introduction.htm
helps too.

Hope this is more helpful, even if it a little late.

- David Joyner


On Thu, Apr 17, 2008 at 8:07 AM, Harald Schilly
<[EMAIL PROTECTED]> wrote:
>
> Hi
>
> A friend of mine want's to manipulate pictures (bitmap, in color).
> Basically, he want's to load and then represent them as a binary
> vector in Sage and then encode them using linear codes ->
> manipulations (errors) -> then back to an image and see how good the
> code worked.
> The one thing I don't know is what's the best and easiest way to get a
> binary representation of an image to be able to work with - a
> bijection from picture to binary vector in GF(2) and back. Maybe in
> different versions (each color channel separate or other methods).
>
> Harald
> >
>

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