var imagenumber = 17 ;
var randomnumber = Math.random() ;
var rand1 = Math.round( (imagenumber-1) * randomnumber) + 1 ;
// Definimos un array de imágenes.
images = new Array
images[1] = "img_intro/angeles.jpg"
images[2] = "img_intro/behemoth.jpg"
images[3] = "img_intro/doro.jpg"
images[4] = "img_intro/doro-pesh.jpg"
images[5] = "img_intro/edguy.jpg"
images[6] = "img_intro/epica.jpg"
images[7] = "img_intro/hammerfall.jpg"
images[8] = "img_intro/iron.jpg"
images[9] = "img_intro/joe-satriani.jpg"
images[10] = "img_intro/judas-priest.jpg"
images[11] = "img_intro/king.jpg"
images[12] = "img_intro/king-diamond.jpg"
images[13] = "img_intro/manowar.jpg"
images[14] = "img_intro/mayhem.jpg"
images[15] = "img_intro/nightwish.jpg"
images[16] = "img_intro/rhapsody.jpg"
images[17] = "img_intro/saxon.jpg"
var image = images[rand1]
// image guarda la imagen del índice (obtenido de forma aleatoria) del array