var imgLength = imgName.length - 1;

// Browser flag for Opera
var op = !!(window.opera && document.getElementById);

function chgImg(direction) {
    if (document.images) {
        imgNum = imgNum + direction;
        if (imgNum > imgLength) {
            imgNum = 0;
        }
        if (imgNum < 0) {
            imgNum = imgLength;
        }
        document.slideshow.src = directory + imgName[imgNum];
        if (op) {
            document.getElementById("frameNumber").innerHTML = "Image " + (imgNum+1) +  " of " + imgName.length;
            document.getElementById("frameCaption").innerHTML = imgText[imgNum];
        }
    }
}

function writeCaption(){
    if (document.getElementById){
        document.getElementById("frameNumber").innerHTML = "Image " + (imgNum+1) +  " of " + imgName.length;
        if (imgText[imgNum].length > 0) {
           document.getElementById("frameCaption").innerHTML = imgText[imgNum];
        } else {
           document.getElementById("frameCaption").innerHTML = "&nbsp;";
        }
    }
}