header() and readfile() [bandwidth issues]

Webase

Hello.

I'm making a script so I can rotate a few images that are outside my website (eg. uploaded at imageshack).

header("Content-type: image/png"); 
readfile($images[$rand_img]);

Readfile() will make it use the bandwidth = the image size right? I then tried to use header(), which didn't work very well. When I inserted the link to the avatar of a forum, it got all stretched, sometimes it wouldn't load.

header("Location: ".$images[$rand_img]);

Is there anyway I can do this without using too much bandwidth?
Thanks!

ClarkF1

If you're pulling it off another website you're always going to use bandwidth.

Webase

But <img src="outside url"> won't pull my bandwidth, will it?
I want to seem like an inside url, that gets outside URLs

ClarkF1

I don't think so because that's done by the browser whereas the other two are done by the server before being sent to the browser

Webase

Once I read the file, how do I get it's attributes?
Using getimagesize() to an external URL, downloads the whole image? I want only to read the file if it's an image, how can I verify if it's an image and it's external? I need to use getimagesize() after or before the readfile()?

Thanks!