function mimagen(id){
idaux=id;
id=id+"blue";
document.getElementById(id).style.visibility="hidden"; 
document.getElementById(idaux).style.visibility="visible"; 

}

function oimagen(id){
idaux=id;
id=id+"blue";
document.getElementById(id).style.visibility="visible"; 
document.getElementById(idaux).style.visibility="hidden"; 
}