function visibility(element, action){
document.getElementById(element).style.visibility=action;
}

function maincaption(){
document.getElementById('info1').style.visibility="hidden";
document.getElementById('infobg1').style.visibility="hidden";
}

function hidereveal(){
document.getElementById('info').style.visibility="hidden";
document.getElementById('infobg').style.visibility="hidden";
}

function roll(img_name, img_src){
document[img_name].src = img_src;
}