function doViewImage( _url, _width, _height )
{
var _top, _left;
_top = (window.screen.height - _height) /2;
_left =(window.screen.width - _width) /2;
b_w = window.open ("", "Preview", "top="+ _top + ",left=" + _left +",width=" + _width + ", height=" + _height + ",status=no,toolbar=no,menubar=no,location=no,scrollbars=no,titlebar=no");
b_w.document.write('Bild Preview');
b_w.document.write('');
b_w.document.write('');
b_w.document.write(' ');
b_w.document.write(' |
');
}