function captionToggleON(id) {
    for (i = 1; i < 5; i++) {
        document.getElementById("divCaption" + i).style.visibility = 'hidden';
    }
    document.getElementById("divCaption" + id).style.visibility = 'visible';
}

function captionToggleOFF() {
    for (i = 1; i < 5; i++) {
        document.getElementById("divCaption" + i).style.visibility = 'hidden';
    }
}