var _URL = window.URL || window.webkitURL;
function displayPreview(files) {
   var file = files[0]
   var img = new Image();
   var sizeKB = file.size / 1024;
   img.onload = function() {
      $('#preview').append(img);
      alert("Size: " + sizeKB + "KBnWidth: " + img.width + "nHeight: " + img.height);
   }
   img.src = _URL.createObjectURL(file);
}