function setUpSlideshow() {
    setInterval('blendimage("slideshow_div", "slideshow_img", "", 1000)', 5000);
}

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 + ")"; 
}

function blendimage(divid, imageid, imagefile, millisec) { 
    imagefile = 'img/custom/thumbnails/'+images[key];
    $('slideshow_a').href = 'custom.php?file='+images[key];
    key++;
    key = (key == length) ? 0 : key;
    var speed = Math.round(millisec / 100); 
    var timer = 0; 
     
    //set the current image as background 
    document.getElementById(divid).style.backgroundImage = "url(" + document.getElementById(imageid).src + ")"; 
     
    //make image transparent 
    changeOpac(0, imageid); 
     
    //make new image 
    document.getElementById(imageid).src = imagefile; 

    $('slideshow_div').style.border = '1px solid #666';

    //fade in image 
    for(i = 0; i <= 100; i++) { 
        setTimeout("changeOpac(" + i + ",'" + imageid + "')",(timer * speed)); 
        timer++; 
    }
}