var image_layer = null;
function display_image_layer(image_src, image_width, image_height) {
	if(document.getElementById) {
		image_layer = document.getElementById('imagelayer');
	} else {
		alert('Das Bild kann leider nicht angezeigt werden');
	}
	if(image_width % 2 != 0) image_width--;
	if(image_height % 2 != 0) image_height--;
	document.images['zoomimage'].src = image_src;
	image_layer.style.width = image_width + 'px';
	image_layer.style.height = (image_height + 20) + 'px';
	image_layer.style.marginLeft = (-1 * image_width / 2) + 'px';
	image_layer.style.marginTop = (-1 * (image_height + 20) / 2) + 'px';
	image_layer.style.display = 'block';
}
function hide_image_layer() {
	image_layer.style.display = 'none';
}