Is it possible to get image size before/without downloading?

[Josiah Manson]

In the head of an HTTP response, most servers will specify a
Content-Length that is the number of bytes in the body of the response.
Normally, when using the GET method, the header is returned with the
body following. It is possible to make a HEAD request to the server
that will only return header information that will hopefully tell you
the file size.

If you want to know the actual dimensions of the image, I don't know of
anything in HTTP that will tell you. You will probably just have to
download the image to find that out. Relevant HTTP specs below if you
care.

http://www.w3.org/Protocols/rfc2616/rfc2616-sec9.html
http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html

The above is true regardless of language. In python it appears there an
httplib module. I would call request using the method head.

http://docs.python.org/lib/httpconnection-objects.html

aldonnelley at gmail.com wrote:
> Hi there: a bit of a left-field question, I think.
> I'm writing a program that analyses image files downloaded with a basic
> crawler, and it's slow, mainly because I only want to analyse files
> within a certain size range, and I'm having to download all the files
> on the page, open them, get their size, and then only analyse the ones
> that are in that size range.
> Is there a way (in python, of course!) to get the size of images before
> or without downloading them? I've checked around, and I can't seem to
> find anything promising...
> 
> Anybody got any clues?
> 
> Cheers, Al.