Can't open image retrieved from S3 with PIL

[rootsmith]

I know this may be more of a question for PIL people but I'm thinking
*somebody* must be doing this exact same scenario with boto.

If I retrieve an image from boto and then try and open it with PIL I
get an IOError: cannot identify image file.

Here is the code:

s3 = S3Connection('blah','blah')
bucket = s3.get_bucket('my_bucket')
key = bucket.get_key(key_name)
file = StringIO()
key.get_file(file)
Image.open(file) # PIL
# .. here I wish to crop the image before spitting it back to the
calling environment

I know that I can successfully retrieve the file because if take out
the PIL code and turn around and set the Content-Type header to image/
jpeg and fire the file object back at the browser (this code is in a
web app controller) the image appears just fine!

By briefly looking at the code in PIL it is inspecting the first 16
bytes of the file and determining if it can recognize it but I don't
understand why it isn't recognizing it.

Any suggestions?

[Chris Moyer]

What happens if you use a TemporaryFile instead of a StringIO, for
that matter what happens if you actually download the file to a local
filesystem before sending it off to PIL?

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[Kevin J. Smith]

Same result if I use TemporaryFile, however, everything works just
fine if I download the file to disk first and then open with PIL. But
I am trying to avoid the disk write then read again for performance.
Again, from the evidence there doesn't appear to be anything wrong
with the file.

KJS

[Matt Billenstein]

Dump the contents of the StringIO to a file and diff to the actual image
-- either you're getting the correct data or it's getting garbled
somewhere...

m

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[Victor Trac]

What happens if, using TemporaryFile, you do:

...

key.get_file(file)

file.seek(0)

Image.open(file) 

...

-- Victor

[Kevin J. Smith]

AH!  That's it!  The operation of key.get_file(file) must end at the end of the file after writing in the contents (...makes sense...) so I need to seek out the beginning of the file before passing it to PIL.

I am still using StringIO btw so it is not necessary to go to a TemporaryFile to get it to work.

Cheers all, thanks for the help!

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