Find out a pic size?

["milisphp" <milis@indoinformatika.com>]

Hi, 
 
I'm working with a lot of picture in a website and the size is not
always the same.
 
I need some help on how to find out the size (width and height) of a
picture. Is there any way to do this (especially with PHP)? 
 
I need it so I can calculate the width and height to be specified on the
HTML <img> tag.
 
Thanks,
 
Hansen
IndoInformatika