var numImg	=	5;
var timer	=	7.5; //  In seconden

function imgCycle(i)
{
	var obj = document.getElementById("header_middle");
	obj.style.background = 'url("img/headers/header_' + i + '.png")';
	obj.style.backgroundRepeat = 'no-repeat';
	obj.style.backgroundColor = '#000';
	
	i++;
	
	if (i > numImg)
		i = 1;

	setTimeout("imgCycle(" + i + ")", (timer*1000));
}