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Date: Thu, 08 Mar 2012 17:56:36 -0500
From: Dave Angel <d@davea.name>
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To: Tobiah <toby@tobiah.org>
Subject: Re: Finding MIME type for a data stream
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On 03/08/2012 05:28 PM, Tobiah wrote:
> <snip>
>
>
> I should simplify my question.  Let's say I have a string
> that contains image data called 'mystring'.
>
> I want to do
>
> mime_type = some_magic(mystring)
>
> and get back 'image/jpg' or 'image/png' or whatever is
> appropriate for the image data.
>
> Thanks!
>
> Tobiah

I have to assume you're talking python 2, since in python 3, strings 
cannot generally contain image data.  In python 2, characters are pretty 
much interchangeable with bytes.

Anyway, I don't know any way in the standard lib to distinguish 
arbitrary image formats.  (There very well could be one.)  The file 
program I referred to was an external utility, which you could run with 
the multiprocessing module.

if you're looking for a specific, small list of file formats, you could 
make yourself a signature list.  Most (not all) formats distinguish 
themselves in the first few bytes.  For example, a standard zip file 
starts with "PK" for Phil Katz.  A Windows  exe starts with "MZ" for 
Mark Zbikowsky.  And I believe a jpeg file starts  hex(d8) (ff) (e0) (ff)

If you'd like to see a list of available modules, help() is your 
friend.  You can start with help("modules") to see quite a long list.  
And I was surprised how many image related things already are there.  So 
maybe there's something I don't know about that could help.

-- 

DaveA