function opacity(id, opacStart, opacEnd, millisec, aid) {
        //speed for each frame
        var speed = Math.round(millisec / 100);
        var timer = 0;

        //determine the direction for the blending, if start and end are the same nothing happens
        if(opacStart > opacEnd) {
                for(i = opacStart; i >= opacEnd; i--) {
                        clearTimeout(imagebox[aid][i]);
                        imagebox[aid][i] = setTimeout("changeOpac(" + i + ",'" + id + "')",(timer * speed));
                        timer++;
                }
        } else if(opacStart < opacEnd) {
                for(i = opacStart; i <= opacEnd; i++)
                {
                        clearTimeout(imagebox[aid][i]);
                        imagebox[aid][i] = setTimeout("changeOpac(" + i + ",'" + id + "')",(timer * speed));
                        timer++;
                }
        }
}

//change the opacity for different browsers
function changeOpac(opacity, id) {
        var object = document.getElementById(id).style;
        object.opacity = (opacity / 100);
        object.MozOpacity = (opacity / 100);
        object.KhtmlOpacity = (opacity / 100);
        object.filter = "alpha(opacity=" + opacity + ")";
}