[SOLVED] Get PHP to check a certain image's dimensions

[Eminem]

I want to make an input box where users will place a URL of an image in.

 

How do I make it so that PHP checks if it's a PNG and if it has a certain height and width in an if statement?

[phpSensei]

<?php

$site = $_POST['IMAGE_URL'];

list($width, $height, $type, $attr) = getimagesize($site);

if($type == "image/png"){ // not so sure about this
if(($height == 100)&&($width == 100)){

// do something
}
}

?>