function slideshow() {
                   max_number_img = 8;
                   i = 3;
                   dispari = true;
                   timer_cambio_img = setInterval('rullo()', 3000);
               }
               function rullo() {
                   browser = null;
                   if (window.ActiveXObject) {
                       if (navigator.userAgent.toLowerCase().indexOf("msie 5") != -1) {
                           browser = "ie";
                       } else {
                           browser = "ie";
                       }
                   }
                   if (!browser && typeof (XMLHttpRequest) != 'undefined') {
                       browser = "ch";
                   }
                   if (i < 10) {
                       src = "img" + "0" + i;
                   } else {
                       src = "img" + i;
                   }

                   timer_fade = setInterval('fade()', 100)
               }
               function fade() {
                   if (browser == "ie") {
                       if (dispari) {
                           var valore1 = document.getElementById("box_01").filters.alpha.opacity;
                           var valore2 = document.getElementById("box_02").filters.alpha.opacity;
                           var incremento = 5;
                           if (valore1 < 100) {
                               valore1 = valore1 + incremento;
                               document.getElementById("box_01").filters.alpha.opacity = valore1;
                               valore2 = valore2 - incremento;
                               document.getElementById("box_02").filters.alpha.opacity = valore2;
                           } else {
                               stop_timer(timer_fade);
                               dispari = false;
                               document.getElementById("box_02").src = "images/" + src + ".jpg";
                               if (i < max_number_img) {
                                   i++;
                               } else {
                                   i = 1;
                               }

                           }
                       } else {
                           var valore1 = document.getElementById("box_02").filters.alpha.opacity;
                           var valore2 = document.getElementById("box_01").filters.alpha.opacity;
                           var incremento = 5;
                           if (valore1 < 100) {
                               valore1 = valore1 + incremento;
                               document.getElementById("box_02").filters.alpha.opacity = valore1;
                               valore2 = valore2 - incremento;
                               document.getElementById("box_01").filters.alpha.opacity = valore2;
                           } else {
                               stop_timer(timer_fade);
                               dispari = true;
                               document.getElementById("box_01").src = "images/" + src + ".jpg";
                               if (i < max_number_img) {
                                   i++;
                               } else {
                                   i = 1;
                               }
                           }
                       }
                   } else {
                       if (dispari) {
                           var valore1 = document.getElementById("box_01").style.opacity;
                           var valore2 = document.getElementById("box_02").style.opacity;
                           var incremento = 0.1;
                           if (valore1 < 1) {
                               valore1 = eval(valore1) + eval(incremento);
                               document.getElementById("box_01").style.opacity = valore1;
                               valore2 = eval(valore2) - eval(incremento);
                               document.getElementById("box_02").style.opacity = valore2;
                           } else {
                               stop_timer(timer_fade);
                               dispari = false;
                               document.getElementById("box_02").src = "images/" + src + ".jpg";
                               if (i < max_number_img) {
                                   i++;
                               } else {
                                   i = 1;
                               }

                           }
                       } else {
                           var valore1 = document.getElementById("box_02").style.opacity;
                           var valore2 = document.getElementById("box_01").style.opacity;
                           var incremento = 0.1;
                           if (valore1 < 1) {
                               valore1 = eval(valore1) + eval(incremento);
                               document.getElementById("box_02").style.opacity = valore1;
                               valore2 = eval(valore2) - eval(incremento);
                               document.getElementById("box_01").style.opacity = valore2;
                           } else {
                               stop_timer(timer_fade);
                               dispari = true;
                               document.getElementById("box_01").src = "images/" + src + ".jpg";
                               if (i < max_number_img) {
                                   i++;
                               } else {
                                   i = 1;
                               }
                           }
                       }
                   }
               }
               function stop_timer(id) {
                   clearInterval(id);
               }