var newImg = new Image;
var indice = 0;
var indice2 = 0;
var nbimg = 0;
var nbimg2 = 0;

function changeImage(imgTarget, imgUrl){
	new Effect.Fade(imgTarget, {
		duration: .4,
		afterFinish: function(){
			newImg.onload = function(){
			$(imgTarget).src = newImg.src;
				new Effect.Appear(imgTarget);
			}
			newImg.src = imgUrl;
		}
	});
}

function initBtn(){
	nbimg = img.length;
	nbimg2 = img2.length;
	setInterval("next()", 6000);
	setInterval("next2()", 4000);
}

function next(e){
	indice++;
	if(indice == nbimg)
		indice = 0;
	changeImage('monImage', img[indice]['url'])
}

function next2(e){
	indice2++;
	if(indice2 == nbimg2)
		indice2 = 0;
	changeImage('monImage2', img2[indice2]['url'])
}

Event.observe(window, 'load', initBtn);