[jQuery] get image size?

I haveing an issue with this:
$("#ver_bildname").change(function () {
var width = $(this).width();
alert(width);
});
returns always 272?
Whatever picture I try, the answer is alsway 272.
$(this).val(); returns me the correct name,
var ext = $('#ver_bildname').val().split('.').pop().toLowerCase(); the
coorect file extension....
How can I get the current image size?
THANKS!!