function initRollOverImages() {
  var image_cache = new Object();
  jQuery("img.swap").each(function(i) {
    var imgsrc = this.src;
    var dot = this.src.lastIndexOf('.');
    var imgsrc_on = this.src.substr(0, dot) + '_on' + this.src.substr(dot, 4);
    image_cache[this.src] = new Image();
    image_cache[this.src].src = imgsrc_on;
    jQuery(this).hover(
      function() { this.src = imgsrc_on; },
      function() { this.src = imgsrc; });
  });
}


function onChangeImage(id) {
	var orig_image_path = $(id).attr("src");
	var dot = orig_image_path.lastIndexOf('.');
    var imgsrc_on = orig_image_path.substr(0, dot) + '_on' + orig_image_path.substr(dot, 4);

	$(id).attr("src", imgsrc_on);
}

function offChangeImage(id) {
	var orig_image_path = $(id).attr("src");
    var dot = orig_image_path.lastIndexOf('.');
	var on = orig_image_path.lastIndexOf('_on');
	var imgsrc_off = orig_image_path.substr(0, on) + orig_image_path.substr(dot, 4);

	$(id).attr("src", imgsrc_off);
}

jQuery(document).ready(initRollOverImages);