function opacity(id, opacStart, opacEnd, millisec) {
 //speed for each frame
 var speed = Math.round(millisec / 100);
 var timer = 0;

 //determine the direction for the blending, if start and end are the same nothing happens
 if(opacStart > opacEnd) {
  for(i = opacStart; i >= opacEnd; i--) {
   setTimeout("changeOpac(" + i + ",'" + id + "')",(timer * speed));
   timer++;
  }
 } else if(opacStart < opacEnd) {
  for(i = opacStart; i <= opacEnd; i++)
   {
   setTimeout("changeOpac(" + i + ",'" + id + "')",(timer * speed));
   timer++;
  }
 }
}

//change the opacity for different browsers
function changeOpac(opacity, id) {
 var object = document.getElementById(id).style; 
 object.opacity = (opacity / 100);
 object.MozOpacity = (opacity / 100);
 object.KhtmlOpacity = (opacity / 100);
 object.filter = "alpha(opacity=" + opacity + ")";
}

function shiftOpacity(id, millisec) {
 //if an element is invisible, make it visible, else make it ivisible
 if(document.getElementById(id).style.opacity == 0) {
  opacity(id, 0, 100, millisec);
 } else {
  opacity(id, 100, 0, millisec);
 }
}

function blendimage(divid, imageid, imagefile, millisec) {
 var speed = Math.round(millisec / 100);
 var timer = 0;
 
 //set the current image as background
 document.getElementById(divid).style.backgroundImage = "url(" + document.getElementById(imageid).src + ")";
 
 //make image transparent
 changeOpac(0, imageid);
 
 //make new image
 document.getElementById(imageid).src = imagefile;

 //fade in image
 for(i = 0; i <= 100; i++) {
  setTimeout("changeOpac(" + i + ",'" + imageid + "')",(timer * speed));
  timer++;
 }
}

function currentOpac(id, opacEnd, millisec) {
 //standard opacity is 100
 var currentOpac = 100;
 
 //if the element has an opacity set, get it
 if(document.getElementById(id).style.opacity < 100) {
  currentOpac = document.getElementById(id).style.opacity * 100;
 }

 //call for the function that changes the opacity
 opacity(id, currentOpac, opacEnd, millisec)
}