function initLightbox() { 

	Lightbox.prototype.updateDetails = function() {
	
		// if caption is not null
		if(imageArray[activeImage][1]){
			Element.show('caption');
			Element.setInnerHTML( 'caption', imageArray[activeImage][1]);
		}
		
		// if image is part of set display 'Image x of x' 
		if(imageArray.length > 1){
			Element.show('numberDisplay');
			Element.setInnerHTML( 'numberDisplay', "Bild " + eval(activeImage + 1) + " von " + imageArray.length);
		}

		new Effect.Parallel(
			[ new Effect.SlideDown( 'imageDataContainer', { sync: true, duration: resizeDuration, from: 0.0, to: 1.0 }), 
			  new Effect.Appear('imageDataContainer', { sync: true, duration: resizeDuration }) ], 
			{ duration: resizeDuration, afterFinish: function() {
				// update overlay size and update nav
				var arrayPageSize = getPageSize();
				Element.setHeight('overlay', arrayPageSize[1]);
				myLightbox.updateNav();
				}
			} 
		);
	};

	myLightbox = new Lightbox(); 
}

Event.observe(window, 'load', initLightbox, false);