function viewPic(img)
{    
   picfile = new Image(); 
   picfile.src =(img); 
   fileCheck(img); 
}

function fileCheck(img)
{    
   if( (picfile.width!=0) && (picfile.height!=0) )
   { 
       makeWindow(img); 
   }
   else 
   {
       funzione="fileCheck('"+img+"')"; 
       intervallo=setTimeout(funzione,8); 
   }
}

function makeWindow(img)
{    
   wd = picfile.width + 20; 
   ht = picfile.height + 20;
   var args= "height=" + ht;
   args += ",width=" + wd;
   if (window.screen) 
   { 
       var avht = screen.availHeight - 30; 
       var avwd = screen.availWidth - 10;
       var xcen = (avwd - wd) / 2; 
       var ycen = (avht - ht) / 2;
       args += ",left=" + xcen + ",screenX=" + xcen;
       args += ",top=" + ycen + ",screenY=" + ycen + ",resizable=yes";    
   }
   return window.open(img, 'x', args); 
}