upload images of a certain size

[SmoothDime]

Im using a simple html form to upload images to my server.

i'd like to only allow images that are of a certain dimensions to be uploaded. i only want images that are 15 pixeles by 15 pixels to pass through the uploading process.

so how can i determine the width and height of the image before i save it onto my server?

does PHP have these variables available of do i have to use gd?

[b.rich]

have a look here:

http://us3.php.net/manual/en/function.getimagesize.php