function skip(n) {
 	
	nextImage = globalID + n;
 	
 	if( nextImage < 0 ){
		nextImage = imagedesc.length-1;
	}
 	if( nextImage > imagedesc.length-1){
		nextImage = 0;
	}			 
 	
 	openLayer(nextImage);			 
}
 			
 			
 			 
// galerie popup oeffnen	
function openLayer(id) {
		
	globalID = id;
		
	// container leeren
	
 	// dynamische Bildsource (wg. caching)
	temp = (Math.round(Math.random() * 600000) + 400000);
 	myNewImageSource = dsBase + imagedesc[id]['image_big'] + "?" + temp;



	var tmpImg = new Image();
	tmpImg.src = myNewImageSource;
 		
 		
 	tmpImg.onload = function() {
 		
 		// check image orientation
 		if(tmpImg) {
 			if (tmpImg.width>tmpImg.height) {
 				$('imageholder').setStyle('width','575px');		
 				
 			} else if (tmpImg.width<tmpImg.height) {
 				$('imageholder').setStyle('width','475px');
 			} else {
 				$('imageholder').setStyle('width','auto');
 			}
 			
 		} else {
 			return(false);
 		}

		if($('imageholder').style.display != 'block') {
	 		// anzeigen
	 		$('imagecontainer').innerHTML = '';
			var createImage = new Element('img', {
	     			'src' : myNewImageSource
	     		}).injectInside($('imagecontainer'));
	 		$('image_description').innerHTML = imagedesc[id]['description'];
	 		$('imagetitle').innerHTML = imagedesc[id]['caption'];
	 		$('imageholder').setStyle('display','block');
			var showMe = new Fx.Style($('imageholder'), 'opacity', {duration: 300} ).start(1);
	 	} else {
	 		
			var hideMe = new Fx.Style($('imageholder'), 'opacity', {
		 	duration: 300,
		 	onComplete: function() {
	 			$('imagecontainer').innerHTML = '';
		     		var createImage = new Element('img', {
		     			'src' : myNewImageSource
		     		}).injectInside($('imagecontainer'));			 	
		 		$('image_description').innerHTML = imagedesc[id]['description'];
		 		$('imagetitle').innerHTML = imagedesc[id]['caption'];
		 		$('imageholder').setStyle('display','block');
				var showMe = new Fx.Style($('imageholder'), 'opacity', {duration: 50} ).start(1);
	     		}
	     		 
		 	}).start(0);	
		}
	}
 	     		
}
 
function closeLayer() {
	 
 	var hideMe = new Fx.Style($('imageholder'), 'opacity', {
 	duration: 300,
 	onComplete: function() {
		$('imageholder').setStyle('display','none');
	}
	 
 	}).start(0);
 	
}