window.addEvent('load', function() {
    $$(".image_on").each(function(image, i) {
        image.addEvents({
            'mouseenter': function() {
                if (Browser.Engine.trident==true) {
                    image.setStyle('opacity', '1');
                } else {
                    image.tween('opacity', '1');
                }
            },
            'mouseleave': function() {
                if (Browser.Engine.trident == true) {
                    image.setStyle('opacity', '0.01');
                } else {
                    image.tween('opacity', '0.01');
                }
            }
        });
    });

});