//Change the opacity of an element - Cross browser compatible
function changeOpacity(opacity, id) {
var object = document.getElementById(id).style;
	object.opacity = (opacity / 100);
	object.filter = "alpha(opacity=" + opacity + ")";
	object.MsFilter = "alpha(opacity=" + opacity + ")";
}

//Blend one image into another by fading a foreground image to reveal the background of a div
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
    changeOpacity(0, imageId);

    //Set the new image
    document.getElementById(imageId).src = imageFile;

    //Fade in new image
    for(i = 0; i <= 100; i++) {
        setTimeout("changeOpacity(" + i + ",'" + imageId + "')",(timer * speed));
        timer++;
    }
}

//Preload images from an array of filenames
function preloadImages(fileNames) {
	var p = fileNames.length;
	var preLoad = new Array();

	for (var i = 0; i < p; i++){
	   preLoad[i] = new Image();
	   preLoad[i].src = fileNames[i];
	}
}