function preloadImages(urls) {
	var img = new Array();
	for (var i=0; i<urls.length; i++) {
		img[img.length] = new Image();
		img[img.length - 1].scr = urls[i];
	}
}

window.onload = function() {
	var img = new Array("img/industrie2.png","img/loisir-et-commerce2.png","img/patrimoine2.png","img/scolaire2.png","img/tertiaire2.png");
	preloadImages(img);
}