Display Image dimensions before loading the image

Display Image dimensions before loading the image

Dear Sir

I am using following jquery to display an image before loading it

Its working perfectly well

I tried but getting the values  of Image's Width and Height Before loading the same

However I am getting its value as   undefined

Pls help

  1. //my code for getting height , width 
  2. var filesize=this.files[0].size/1024 ; var width = this.files[0].width; var height= this.files[0].height; alert('Height'+height+' Width='+width);
  3. //

  1. <script type="text/javascript">

  2. $(document).ready(function() {  
  3.   
  4.  $('#image1').bind('change', function() {
  5.  
  6.       $('#image1message').empty("");
  7.       $('#image1preview').empty("");
  8.         $('#image1size').text( "File size :"+this.files[0].size/1024  + "KB");
  9. var filesize=this.files[0].size/1024 ;

  10. //my code for getting height , width 
  11. var filesize=this.files[0].size/1024 ; var width = this.files[0].width; var height= this.files[0].height; alert('Height'+height+' Width='+width);
  12. //


  13.  
  14.   if (filesize > 900) 
  15. { $('#image1message').html("File size cannot exceed 650");
  16.     $('#image1message').css('font-family','Arial, Helvetica, sans-serif');
  17.   $('#image1message').css('font-size','18px');
  18.   $('#image1message').css('font-family','Arial, Helvetica, sans-serif');
  19.   $('#image1message').css('color','#F00');
  20.   
  21.   
  22.   $('#image1').focus();
  23.   $('#Submit').hide(1000);
  24. }
  25. else
  26. {   
  27.    $('#image1message').html("");
  28.    $('#Submit').show(1000);
  29. }
  30.   var file = $('#image1')[0].files[0];
  31.       var reader = new FileReader();
  32.         var img = new Image();
  33.         var _URL = window.URL || window.webkitURL;
  34.         reader.readAsDataURL(file);
  35.         reader.onload = function(_file) {
  36.             img.src= _file.target.result;
  37.             $('#image1preview').append('<img src="'+ img.src +'" width=150 />');
  38.            //console.log(img.src);
  39. }
  40.    });
  41.    });

  42.  </script>