Add picture JsPDF

I have this script that generates a pdf of a div . But the images that contain div are not generated in pdf , can anyone help me?

$('#downloadpdf').click(function() 
                {
                    var doc = new jsPDF('landscape', 'pt', 'a4');
                        doc.addHTML($('#dowextrato'), function()
                    {
                        doc.save("relatorio-<?php echo $Pnome; ?>.pdf");
                    }); 
                });