togliere sfondo

[iceberg]

Ciao ho js che mi visualizza delle immagini in un menu

come posso non visualizzare lo sfondo dei png... anche se i png hanno fondo trasparente, viene visualizzato in azzurro

function Dock(node, imageDetails, minimumSize, maximumSize, range){

  // Preload images
  var images = new Array();
  for (var i = 0; i < imageDetails.length; i++){
    for (var j = 0; j < imageDetails[i].sizes.length; j++){
      var image = new Image(imageDetails[i].sizes[j],imageDetails[i].sizes[j]);
      image.src = imageDetails[i].name
                + imageDetails[i].sizes[j]
                + imageDetails[i].extension;
      images.push(image);
    }
  }

  // Create the toolbar
  var scale         = 0;
  var closeTimeout  = null;
  var closeInterval = null;
  var openInterval  = null;
  var imageNodes    = new Array(imageDetails.length);
  var imageSizes    = new Array(imageDetails.length);
  node.style.textAlign = 'center';
  node.style.height    = maximumSize + 'px';
  for (var i = 0; i < imageDetails.length; i++){
    imageNodes[i] = document.createElement('img');
    imageSizes[i] = minimumSize;
    imageNodes[i].style.position = 'relative';
    setImageProperties(i);
    node.appendChild(imageNodes[i]);
    if (imageNodes[i].addEventListener){
      imageNodes[i].addEventListener('mousemove', processMouseMove, false); 
      imageNodes[i].addEventListener('mouseout', processMouseOut, false);
      imageNodes[i].addEventListener('click', imageDetails[i].onclick, false);
    }else if (imageNodes[i].attachEvent){
      imageNodes[i].attachEvent('onmousemove', processMouseMove);
      imageNodes[i].attachEvent('onmouseout', processMouseOut);
      imageNodes[i].attachEvent('onclick', imageDetails[i].onclick);
    }
  }

  /* Sets a toolbar image to the specified size. The parameters are:
   *
   * index - the 0-based index of the image to be sized
   */
  function setImageProperties(index){
    var imageNode = imageNodes[index];
    var details   = imageDetails[index];
    var size = minimumSize + scale * (imageSizes[index] - minimumSize);
    var sizeIndex = -1;
    do{
      sizeIndex++;
    }while (sizeIndex < details.sizes.length
        &&  details.sizes[sizeIndex] < size)
    if (sizeIndex >= details.sizes.length) sizeIndex--;
    imageNode.setAttribute('src',
        details.name + details.sizes[sizeIndex] + details.extension);
    imageNode.setAttribute('width',  size);
    imageNode.setAttribute('height', size);
    imageNode.style.marginTop = (maximumSize - size) + 'px';
  }

  /* Processes a mousemove event on an image in the 'dock'. The parameters are:
   *
   * e - the mousemove event. window.event will be used if this is undefined.
   */
   function processMouseMove(e){
    if (!e) e = window.event;
    var target = e.target || e.srcElement;
    var index = 0;
    window.clearTimeout(closeTimeout);
    closeTimeout = null;
    window.clearInterval(closeInterval);
    closeInterval = null;
    if (scale != 1 && !openInterval){
      openInterval = window.setInterval(
          function(){
            if (scale < 1) scale += 0.125;
            if (scale >= 1){
              scale = 1;
              window.clearInterval(openInterval);
              openInterval = null;
            }
            for (var i = 0; i < imageNodes.length; i++){
              setImageProperties(i);
            }
          },
          20);
    }
    while (imageNodes[index] != target) index++;
    var across = (e.layerX || e.offsetX) / imageSizes[index];
    if (across){
      for (var i = 0; i < imageSizes.length; i++){
        if ((i < index - range) || (i > index + range)){
          imageSizes[i] = minimumSize;
        }else{
          imageSizes[i] = minimumSize
                        + Math.ceil((maximumSize - minimumSize)
                            * (Math.cos(i - index - across + 0.5) + 1) / 2);
        }
        setImageProperties(i);
      }
    }
  }

  // Processes a mouseout event on an image in the 'dock'.
  function processMouseOut(){
    if (!closeTimeout && !closeInterval){
      closeTimeout = window.setTimeout(
          function(){
            closeTimeout = null;
            if (openInterval){
              window.clearInterval(openInterval);
              openInterval = null;
            }
            closeInterval = window.setInterval(
                function(){
                  if (scale > 0) scale -= 0.125;
                  if (scale <= 0){
                    scale = 0;
                    window.clearInterval(closeInterval);
                    closeInterval = null;
                  }
                  for (var i = 0; i < imageNodes.length; i++){
                    setImageProperties(i);
                  }
                },
                20);
          },
          100);
    }
  }

} 

dove la visualizzazione viene fatta tramite:

var dock = new Dock(
document.getElementById('dock'),
[
{
name: 'templates/webby2/media/toolbar/users',
extension: '.png',
sizes: [128,128],
onclick: function(){
alert('You clicked on the first icon');
}
},