var bgImgNr = Math.floor(Math.random() * 56);
function switchBackgroundImage(){
	var imgArr = new Array("bg_02.jpg", "bg_03.jpg", "bg_05.jpg", "bg_06.jpg", "bg_07.jpg", "bg_08.jpg", "bg_09.jpg", "bg_10.jpg", "bg_12.jpg", "bg_13.jpg", "bg_14.jpg", "bg_15.jpg", "bg_16.jpg", "bg_17.jpg", "bg_19.jpg", "bg_20.jpg", "bg_21.jpg", "bg_23.jpg", "bg_24.jpg", "bg_27.jpg", "bg_29.jpg", "bg_30.jpg", "bg_31.jpg", "bg_33.jpg", "bg_34.jpg", "bg_36.jpg", "bg_37.jpg", "bg_38.jpg", "bg_39.jpg", "bg_40.jpg", "bg_41.jpg", "bg_47.jpg", "bg_48.jpg", "bg_49.jpg", "bg_50.jpg", "bg_51.jpg", "bg_52.jpg", "bg_53.jpg", "bg_54.jpg", "bg_55.jpg", "bg_56.jpg", "bg_57.jpg", "bg_58.jpg", "bg_59.jpg", "bg_60.jpg", "bg_61.jpg", "bg_62.jpg", "bg_63.jpg", "bg_64.jpg", "bg_65.jpg", "bg_66.jpg", "bg_67.jpg", "bg_68.jpg", "bg_69.jpg", "friseur_01.jpg", "kinderbetreuung_02.jpg");
	++bgImgNr;
	var currentImgNr = (bgImgNr%imgArr.length);
	var imgName = imgArr[currentImgNr];
	var newImgUrl = "url(fileadmin/user_upload/images/slideshow/"+imgName+")";
	$('slideshow').style.backgroundImage = newImgUrl;
	new Effect.Opacity('ch_transition', {
		duration:2,
		from:1.0,
		to:0.0,
		afterFinish: function () {
			$('ch_transition').style.backgroundImage = newImgUrl;
			new Effect.Opacity('ch_transition', {	
				duration:0.5,
				from:0.0,
				to:1.0
			});
		}
	});

}
Event.observe(window, 'load', function() {
	switchBackgroundImage();
	new PeriodicalExecuter(switchBackgroundImage, 7);
});