PHP-Image functions

//size of image
getimagesize()
http://www.php.net/getimagesize

//image width
imagesx()
http://www.php.net/manual/en/function.imagesx.php


//image height
imagesy()
http://www.php.net/manual/en/function.imagesy.php

//determine type of an image
exif_imagetype()
http://www.php.net/manual/en/function.exif-imagetype.php