var ObjClr = new Array(19);

function ChangeColor(Obj,Index) {
  var ObjId=document.getElementById(Obj);
  ObjClr[Index] = ObjId.style.color;
  ObjId.style.color= "#CC00FF";
}

function BackColor(Obj,Index) {
  var ObjId=document.getElementById(Obj);
  ObjId.style.color = ObjClr[Index];
}