$(document).ready(function() {
          $("#triquibackimg").load(function(){
               resize_bg();
          })
          $(window).resize(function(){
               resize_bg();
          })
          function resize_bg(){
               $("#triquibackimg").css("left","0");
               var doc_width = $(window).width();
               var doc_height = $(window).height();
               var image_width = $("#triquibackimg").width();
               var image_height = $("#triquibackimg").height();
               var image_ratio = image_width/image_height;      
               var new_width = doc_width;
               var new_height = Math.round(new_width/image_ratio);
               if(new_height<doc_height){
                    new_height = doc_height;
                    new_width = Math.round(new_height*image_ratio);
                    var width_offset = Math.round((new_width-doc_width)/2);
                    $("#triquibackimg").css("left","-"+width_offset+"px");
               }
               $("#triquibackimg").width(new_width);
               $("#triquibackimg").height(new_height);
          }
     });