function Gallerie() {

    var fdur = 1;
    var steps = 30;

    var ftim = fdur*1000/steps;
    var factor = 0;
    var u = 0;

    var hide = null;
    var show = null;

    this.slide = function(image) {

        var div1 = document.getElementById('gal_img1');
        var div2 = document.getElementById('gal_img2');

        if (div1.style.visibility == 'hidden') {
            show = div1;
            hide = div2;
        } else {
            show = div2;
            hide = div1;
        }

        hide.style.zIndex = 2;
        show.style.zIndex = 0;
        show.style.backgroundImage = "url(./images/" + image + ")";

        show.style.visibility = "visible";
        show.style.filter = "Alpha(Opacity=100)";
        show.style.MozOpacity = 1;
        show.style.opacity = 1;

        hide.style.filter = "Alpha(Opacity=100)";
        hide.style.MozOpacity = 1;
        hide.style.opacity = 1;
        factor = 100/steps;
        u = 0;

        slidenow();

    }

    var slidenow = function() {

        var check1 = hide.style.MozOpacity;
        var maxalpha = (100-factor*u)/100*105;
        if(check1 <= maxalpha/100) {
            u+=1;
        }

        var curralpha = 100-factor*u;
        hide.style.filter = "Alpha(Opacity="+curralpha+")";
        hide.style.MozOpacity = curralpha/100;
        hide.style.opacity = curralpha/100;

        if(u < steps) {
            window.setTimeout(slidenow, ftim);
        }

        if(u >= steps) {
            hide.style.visibility = "hidden";
            hide.style.zIndex = 0;
            show.style.zIndex = 2;
            u=0;
        }

    }

}