var state = "out";
var v1 = 1.0;
	
function f1(){
	obj = document.getElementById("img_slide_front");
	if (state == "in") {
		v1 += 0.02;
		if (v1 > 1) {
			v1 = 1.0;
			state = "out";
		}
	}
	else {
		v1 -= 0.02;
		if (v1 < 0) {
			v1 = 0;
			state = "in";
		}
	}
	
	obj.style.opacity = v1; // obj.filters.alpha.opacity=100;
	obj.style.filter = 'alpha(opacity = ' + v1 * 100 + ')';
	
	if (v1 == 1 || v1 == 0) 
		setTimeout("f1()", 5000);
	else 
		setTimeout("f1()", 80);
}