var timeDelay = 2;
var Pix = new Array
("img/immagini_categorie/nature.jpg"
,"img/immagini_categorie/science.jpg"
,"img/immagini_categorie/technology.jpg"
,"img/immagini_categorie/reportage.jpg"
)

var howMany = Pix.length;
timeDelay *= 1000;
var PicCurrentNum = 0;
var PicCurrent = new Image();
PicCurrent.src = Pix[PicCurrentNum];

function startPix() {
	setInterval("slideshow()", timeDelay);
}

function slideshow() {
	PicCurrentNum++;
	if (PicCurrentNum == howMany) {
		PicCurrentNum = 0;
	}
	PicCurrent.src = Pix[PicCurrentNum];
	document["ChangingPix"].src = PicCurrent.src;
}