[man]getimagesize[/man]
that function will return an array of info about an image, including height and width.
example.
$data = getimagesize("http://www.site.com/logo.jpg");
echo "Image width is {$data[0]}, height is {$data[1]}, its type is {$data[2]} ({$data['mime']}) and its html compatible height and width is {$data[3]}";
this may output something like:
Image width is 400, height is 60, its type is 2 (image/jpeg) and its html compatible height and width is height="60" width="400"
