function imgadd(targetid, increase) {
    if (increase) { imgadd_index++; }
    else { imgadd_index--; }
    if (imgadd_index > 5 | imgadd_index < 0) { imgadd_index = 0; }
    document.getElementById(targetid).src = "/images/front.asp?index=" + imgadd_index;
    return false;
}