#img {
width:300px;
height:300px;
overflow:hidden;
background-repeat: no-repeat !important;
background-position: center !important;
background-si
window.onload = function() {
var imageSrc = document
.getElementById('hello')
.style
.backgroundImage
.replace(/url\((['"])?(.*?)\1\)/gi, '$2')
.split(',')[0];
// I just broke it up on newlines for readability
var image = new Image();
image.src = imageSrc;
var width = image.width,
height = image.height;
alert('width =' + width + ', height = ' + height)
}