function Change_image() {
	i = choix.liste_pdf.selectedIndex;
	if (i == 0) return;
	val = choix.liste_pdf.options[i].value;
    image_pdf.src="../" + val.substring(0,val.lastIndexOf("+"));
    val2=val.substring(val.lastIndexOf("+"));
    lien_pdf.href="../" + val2.substring(1);
}