On Thu, Jul 17, 2008 at 8:02 PM, [EMAIL PROTECTED]
<[EMAIL PROTECTED]> wrote:
>
> I'm brand new to Sage, and would like to follow the path of least
> resistance to playing around with images. I tried to follow these
> instructions, but got tripped up.
>
> On May 23, 7:55 am, "David Joyner" <[EMAIL PROTECTED]> wrote:
>> 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 fromhttp://www.pythonware.com/products/pil/. Here's how:
>>
>> (a) download the tarball from a link on the URL mentioned above,
>> sayhttp://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
>
> Instead of doing this, I ran
>
> sage -i PIL-1.1.5.spkg
>
> per the instructions of Simon King. So far so good.
>
>> (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")
>
> I'm good up to this point. im is an object with a bunch of methods
> that I can look at with tab completion.
>
>> sage: im.show(command="display")
I would try
sage: im.show(command="/opt/local/bin/xv")
based on what you say below. Does this help?
>
> No dice. I get the following Traceback:
>
> Traceback (most recent call last):
> File "<stdin>", line 1, in <module>
> File "/Users/jm843/.sage/sage_notebook/worksheets/admin/0/code/
> 31.py", line 6, in <module>
> im.show(command="display")
> File "/Applications/sage/local/lib/python2.5/site-packages/sympy/
> plotting/", line 1, in <module>
>
> File "/Applications/sage/local/lib/python2.5/site-packages/PIL/
> Image.py", line 1349, in show
> _showxv(self, title, command)
> File "/Applications/sage/local/lib/python2.5/site-packages/PIL/
> Image.py", line 1913, in _showxv
> file = image._dump(format=format)
> File "/Applications/sage/local/lib/python2.5/site-packages/PIL/
> Image.py", line 429, in _dump
> self.load()
> File "/Applications/sage/local/lib/python2.5/site-packages/PIL/
> ImageFile.py", line 180, in load
> d = Image._getdecoder(self.mode, d, a, self.decoderconfig)
> File "/Applications/sage/local/lib/python2.5/site-packages/PIL/
> Image.py", line 328, in _getdecoder
> raise IOError("decoder %s not available" % decoder_name)
> IOError: decoder jpeg not available
>
> I'm on a mac here, and I already had ImageMagick installed through
> MacPorts. Since the above didn't work, so i also installed xv.
> Macports installs things into /opt/local/bin
>
> jmerrill:~ jm843$ which xv
> /opt/local/bin/xv
>
> I have /opt/local/bin on my searchpath when I open a terminal, but I
> suspect Sage just doesn't know where to find this stuff. I tried
> running
>
> sys.path.append('/opt/local/bin')
>
> from within a notebook, but it doesn't seem to change anything.
>
>> Of course, im.[TAB] gives you more commands to play with and the online
>> tutorialhttp://www.pythonware.com/library/pil/handbook/introduction.htm
>> helps too.
>>
>> Hope this is more helpful, even if it a little late.
>>
>> - David Joyner
>
> I'm grateful for any suggestions. Is PIL the easiest route to playing
> around with images? I'd really like to be able to get a grayscale
> image into an array of numbers so that I can play with convolutions
> and thresholding and the like.
I'm not sure what the best route is. Really, Sage (and Python) is
lacking in this
area, compared to (say) Matlab. Some references which use Python and GIMP are
www.estig.ipbeja.pt/~jasnau/VisaoComputador/pythonviip.pdf
http://www.mail-archive.com/[EMAIL PROTECTED]/msg14093.html
I'm not sure if PIL+GIMP is the way to go but maybe it's worth thinking about.
>
> Regards,
>
> Jason Merrill
>
> >
>
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