function opacity(id, opacStart, opacEnd, millisec) {
    //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 = i - 2) {
            setTimeout("changeOpac(" + i + ",'" + id + "')",(timer * speed));
            timer++;
        }
    } else if(opacStart < opacEnd) {
        for(i = opacStart; i <= opacEnd; i = i + 2)
            {
            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 + ")";
}



function shiftOpacity(id, millisec) {
    //if an element is invisible, make it visible, else make it ivisible
    if(document.getElementById(id).style.opacity == 0) {
        opacity(id, 0, 100, millisec);
    } else {
        opacity(id, 100, 0, millisec);
    }
}









function cycleFade(num) {
var fadeDuration = 1500;
    for (i = 1; i <= num; i++) {
        if (i == num) { x = 1; }
        else { x = i + 1; }
        var t = 3000 * (i+1);
        setTimeout("shiftOpacity('poloroid"+x+"', "+fadeDuration+"); shiftOpacity('poloroid"+i+"', "+fadeDuration+");", t);
//        setTimeout("shiftOpacity('poloroid"+x+"', "+fadeDuration+"); shiftOpacity('poloroid"+i+"', "+fadeDuration+"); alert('"+i+" - "+x+"');", t);
    }
    setTimeout ("cycleFade("+num+")", 3000*num);
}

function poloroidFade(num) {
    for (i = 1; i <= num; i++) {
//        opacity('poloroid1', 100, 0, 1);

        changeOpac(0, 'poloroid'+i);
    }

    shiftOpacity('poloroid1', 1500);
    cycleFade(num);

}