[711]

Originally Posted by Helios

There is. I've used it myself.

http://uk2.php.net/getimagesize

Examples in the comments.

Just a suggestion.

I am fully aware of auto-picture resizing software available via php.

Perhaps I wasn't clear enough: there is no add-on for vBulletin to do this within a post. I cannot simply paste php code into the pages that run the forum. vBulletin uses a highly-specialized template system to cache and generate the final php pages.