function pngalpha() {
	
	if( navigator.appName == 'Microsoft Internet Explorer' && navigator.platform == 'Win32' ) {

		var picId = 0;
		
		var overlayimage = 'images/spacer.gif';

		while( picId < document.images.length ) {
	
			//Bildtyp ermitteln
			var ext = document.images[picId].src;
			ext = ext.substring(ext.length-3,ext.length);
			ext = ext.toLowerCase();

			if( ext == 'png' ) {

				var src = document.images[picId].src;
				var height = document.images[picId].height;
				var width = document.images[picId].width;

				document.images[picId].src = overlayimage;
				document.images[picId].height = height;
				document.images[picId].width = width;
				document.images[picId].style.filter = "progid:DXImageTransform.Microsoft.AlphaImageLoader(src='" + src + "',sizingMethod='scale')";
	
			}

			++picId;
	
		}

	}
	
}

window.onload = pngalpha;