function image() {
};

image = new image();
number = 0;
// array di immagini
image[number++] = "<img src='images/top_index_ing_2.jpg'>"
image[number++] = "<img src='images/top_index_ing_1.jpg'>"
image[number++] = "<img src='images/top_index_ing.jpg'>"

incremento = Math.floor(Math.random() * number);